Comparison of Design Characteristics and Customization Protocols for Swimming Goggles

electronics

Article Comparison of Design Characteristics and Customization Protocols for Swimming Goggles

Jangwoon Park 1, Mehrube Mehrubeoglu 1, Jungyoon Kim 2 and Jaehyun Park 3,*

1 Department of Engineering, Texas A&M University-Corpus Christi, Corpus Christi, TX 78412, USA; [email protected] (J.P.); [email protected] (M.M.) 2 Department of Computer Science, Kent State University, Kent, OH 44240, USA; [email protected] 3 Department of Industrial & Management Engineering, Incheon National University, Incheon 22012, Korea * Correspondence: [email protected]; Tel.: +82-32-835-8867

Received: 7 May 2020; Accepted: 12 June 2020; Published: 13 June 2020

Abstract: Swimming goggles are important tools for swimmers; however, most of the commercialized swimming goggles are designed as one-size-fits-all, which may cause improper fit to a wearer’s facial shape. The present study is intended to review and compare the design characteristics of the existing swimming goggles and the published customization protocols of swimming goggles. The detailed design characteristics of lens, strap, gasket, and nose bridge of 26 commercialized swimming goggles were reviewed, and the dimensions (length, width, and depth) of five swimming goggles are summarized in this paper. Next, the customization protocols of swimming goggles were investigated, which consisted of three major steps: first step involves collecting a wearer’s 2D or 3D facial shape including eye and nasal root areas by using a hand-held scanner, and then using this scanned data to create a 3D contour shape of customized swimming goggles in a computer-aided design (CAD) environment. Second step requires the fabrication of the designed 3D CAD model of the customized swimming goggles by using a 3D printer using transparent and flexible materials. Third step includes conducting validation tests to evaluate the performance of the customized swimming goggles in terms of waterproofness and wearing comfort by comparing with the other existing goggles. To the best of our knowledge, this is the first paper that reviews the design characteristics of swimming goggles. The review results presented in this paper are particularly useful to develop not only swimming goggles, but also other types of wearable products such as safety goggles, military goggles, and any sort of sports goggles.

Keywords: ergonomic design; swimming goggles; 3D facial scan; wearable device; ﬁt

1. Introduction Swimming goggles are designed to be worn on a swimmer’s face to not only improve visibility but also protect the eyes from harmful chemicals in swimming pools; however, swimming goggles that are not properly fitted at the contact points between the goggles and the wearer’s skin can cause water leakage. Water leaking into the goggles would result in chemical irritants reaching the wearer’s eyes, possibly causing eye irritation and other damage in the long term [1,2]. Similarly, water leakage causes the swimmer to lose visibility and requires the swimmer to adjust the swimming goggles while swimming [3]. Furthermore, wearing swimming goggles by fastening the strap with too much tension may compress orbital vasculature, which causes an elevation in intraocular pressure (IOP) [4]. Note that the continuously elevated IOP is a significant factor affecting glaucoma development and progression [5]. Ma et al. [6] suggested that swimmers should wear properly fitted swimming goggles with straps that are not overly tightened.

Electronics 2020, 9, 992; doi:10.3390/electronics9060992 www.mdpi.com/journal/electronics Electronics 2020, 9, 992 2 of 20

A few studies have been conducted to design swimming goggles to improve wearing fit by customizing the shape of the contacting surface using a swimmer’s facial data. For the first time, Coleman et al. [7] introduced the design protocol of customized swimming goggles using a wearer’s 3D facial scan. In addition, Coleman conducted a human subject experiment to evaluate the customized swimming goggles in terms of waterproofness and wearing comfort compared to existing one-size-fits-all swimming goggles. Park et al. [8,9] conducted a similar study, but they used a typical mobile camera, such as GoPro, to capture the wearer’s 2D facial images without using an expansive 3D scanner. Scanning was followed by digital facial reconstruction using a commercial software tool (Agisoft Photoscan, Agisoft LLC, St. Petersburg, Russia), producing the wearer’s 3D facial image based on the multiple 2D facial images taken at various angles. Park et al. reported that although the reconstruction process of the 3D facial image required at least one hundred 2D selfie images, the quality of the reconstructed 3D facial image, composed of point cloud data, was good enough to design the goggles to fit to the wearer’s skin contours. The previous studies showed potential ergonomic advantages and cost-effective production process of customized swimming goggles. However, research is still limited on the review of detailed design characteristics of the existing swimming goggles, such as shapes, materials, and dimensions. To the best of our knowledge, no research articles exist that compare design characteristics of swimming goggles. The objectives of this study include providing an extensive review and comparison of design features of the existing swimming goggles and the design protocol of customized swimming goggles. The results of this comparative study would be useful to designers, researchers, and manufacturers of swimming goggles.

2. Design Characteristics of Swimming Goggles This section introduces the design characteristics of existing swimming goggles based on the review of the existing swimming goggles [10–35] as well as patents [36–38]. To understand design characteristics of the existing swimming goggles, 26 commercialized swimming goggles were analyzed in terms of their design features and dimensions (see Table1). All the goggles were searched via Amazon.com, and their price range was from $3 to $75 USD (Mean = $21.54; SD = $17.62; min = $2.95; max = $75.00) which would cover typical swimming goggles for exercise as well as sports purposes. The selection of the compared swimming goggles was determined based on the availability of various commercial swimming goggles that users can easily access and purchase without any ﬁnancial burden. Therefore, the price range of the compared swimming goggles was also chosen to cover various existing swimming goggles. We believe that these 26 swimming goggles are representative of most design characteristics of the existing commercial swimming goggles and formed a strong basis for comparison. The authors speciﬁcally analyzed design features, material characteristics of straps, lenses, and nose bridge designs of the goggles. Figure1a shows the summary of results of overall goggle design features. Out of the 26 swimming goggles analyzed, 21 goggles (81%) possess an anti-fog feature and 18 goggles (69%) have ultraviolet (UV) protection. On the other hand, only a few of the goggles include the anti-scratch (3 out of 26, 12%), hypo-allergenic (4 out of 26, 15%), and hydrodynamic design features (8 out of 26, 31%). More specifically, 75% of those eight hydrodynamic goggles possess flat lenses, 50% are designed with symmetric lenses, and 75% have double head straps. Figure1b shows the review results regarding design characteristics and materials of head straps. Based on the review on the 26 existing goggles, all the head straps were designed to be adjustable; 69% of the goggles used double straps, and 31% of the straps were made of silicone. Silicone is being used to replace rubber which contains latex material that might cause allergic reaction in the skin. Figure1c shows the review results regarding the lens of analyzed swimming goggles. 73% of the goggle lenses were designed in an asymmetric shape, 62% of the lenses were designed flat, while 38% of the lens were designed as curved shape. Finally, Figure1d shows the design characteristics of nose bridges. 50% of the goggles have an exchangeable nose bridge. Most of the exchangeable nose bridges (12 out of 13) were made of plastic that do not allow any adjustments while the only one sample is made of a rubber which can provide better flexibility for a user’s preference. Electronics 2020, 9, 992 3 of 20

Electronics 2020, 9, 992 5 of 20 Electronics 2020, 9, 992 Table 1. Design characteristics of the 26 commercialized swimming goggles. 5 of 20 ElectronicsElectronics 2020 2020, 9, ,9 992, 992 5 5of of 20 20 No ModelElectronics Features 2020, 9, 992 Strap/MaterialTable 1. Design characteristics Lens of the 26 commercialized Frame/Gaskets swimming goggles. Nose Bridge Image 5 of 20 Table 1. Design characteristics of the 26 commercialized swimming goggles. - Pre-assembledNo Model with Features Strap/Material Lens Frame/Gaskets Nose Bridge Image - Replaceable latexTable 1. Design characteristics of the 26 commercialized swimming goggles. Nolatex strap Model − PreFeatures-assembled withTable 1.− DesignStrap/MaterialReplaceable characteristics latex of the 26 Lenscommercialized swimmingFrame/Gaskets goggles. Nose Bridge Image bungee strap Table 1. Design characteristics of the 26 commercialized swimming goggles. Sporti Antifog - AdditionSporti black Antifog latex strap bungee strap (through NoNo ModelModel − (throughPreFeatures-Featuresassembled the holes with − -Strap/Material Strap/MaterialReplaceableClear latex - LensLensMounted to lensFrame/GasketsFrame/Gaskets NoseNose Bridge Bridge ImageImage Swedish Goggle + Nobungee SportiSwedish strapModel Antifog Goggle + latex− strapAdditionFeatures black bungeethe holesStrap/Material strap next (through to the − ClearLens − Frame/GasketsMounted to lens- ExchangeableNose Bridge Image 1 1 − − PrenextPre-assembled-assembled to the eyepiece) with with − − - ReplaceableReplaceableFlat latex latex - No gasket − Exchangeable Bungee Strap with goggleSwedishBungee Strap Goggle + −bungee PreAddition strap-assembled with black goggle with −theeyepiece) holesReplaceable next to the latex − ClearFlat − MountedNo gasket to lens 1 SportiSporti Antifog Antifog latexlatex strap adjustablestrap in the backbungeebungee strap strap (through (through − Exchangeable ($2.95) - Ant- fogSportiBungee($2.95) Antifog Strap latexbungee− strapAnt strap- fog with goggle bungeeeyepiece)− adjustable strap (through in the − Flat − No gasket SwedishSwedish Goggle Goggle + + − − AdditiontoAddition customize black black fit thethe holes holes next next to to the the − − ClearClear − − MountedMounted to to lens lens - 1UV 1 ProtectionSwedish($2.95) Goggle + −− AdditionAntUV -Protection fog black the−back holes toadjustable customize next to inthe fit the − Clear − Mounted to lens − − ExchangeableExchangeable 1 BungeeBungee Strap Strap bungeebungee strap strap with with goggle goggle eyepiece)eyepiece) − − FlatFlat − − NoNo gasket gasket − Exchangeable Bungee Strap bungee− UV strap Protection with goggle eyepiece)back to customize fit − Flat − No gasket ($2.95)Sporti($2.95) Antifog − − AntAnt- fogfog − − adjustableadjustable in in the the ($2.95) − Ant- fog − adjustable in the Optical Pro II − − UVUV Protection Protection back−back to toRubber customize customize fit fit − Curved Mounted to lens, with − Fixed and Sporti Antifog 2 Sporti Antifog −N/A UV Protection back to customize fit OpticalMirrored Pro Goggle II - Rubber − - RubberAdjustableCurved − CurvedRevo mirror Mountedrubber gasket to lens, with- Fixed−unexchangeable Fixed and Optical Pro II 2 SportiSporti Antifog Antifog N/A Mounted to lens, with rubber 2 N/A SportiMirrored($8.95) Antifog Goggle - Adjustable − - AdjustableRevo mirror − Revo mirror rubber gasket andunexchangeable unexchangeable Mirrored Goggle OpticalOptical Pro Pro II II − − RubberRubber − − CurvedgasketCurved MountedMounted to to lens, lens, with with − − FixedFixed and and 2 2 Optical($8.95) Pro II N/AN/A − Rubber − Curved Mounted to lens, with − Fixed and ($8.95) 2 MirroredMirrored Goggle Goggle N/A − − AdjustableAdjustable − − RevoRevo mirror mirror rubber−rubber gasketGasket gasket shape offers unexchangeableunexchangeable Mirrored Goggle − Adjustable − Revo mirror rubber gasket unexchangeable ($8.95)($8.95) − G.O. Fit System: −universal fit outside the ($8.95) Gasket shape offers − G.O.Outer Fit eye System: fit - Gasket shapeuniversaleye off socketers fit with outside found the in Speedo Adult 3PK − Clear − − GasketGasket shape shape offers offers − Fixed and - G.O.3 Fit System: − OuterAnti-fog eye fit − Silicone head strap universal fit−eyeother outside socket GasketSpeedo the with shape eyegoggles found offers in SpeedoGoggles Adult ($16.87) 3PK − − G.O.G.O. Fit Fit System: System: − ClearFlat universaluniversal fit fit outside outside the the −un exchangeableFixed and - Outer3 eye fit −− G.O.AntiUV protection- Fitfog System: − Silicone head strap socket with founduniversalother− SpeedoComfortable in fit other outside goggles flex the Goggles ($16.87) − − OuterOuter eye eye fit fit - Clear − Flat eyeeye socket socket with with found found- in in Fixedunexchangeable Speedo Adult 3PK SpeedoSpeedo Adult Adult 3PK 3PK −− OuterUVLatex protection -eyefree fit − − ClearClear Speedo goggleseye−frame socketComfortable that withmoves found with flex in the − − FixedFixed and and 3 - 3Anti-fog 3 Speedo Adult 3PK −- − AntiSiliconeAnti-fog-fog head strap − − SiliconeSilicone head head strap strap − Clear otherother Speedo Speedo goggles goggles − Fixed and Goggles ($16.87) 3 GogglesGoggles ($16.87) ($16.87) − AntiLatex-fog-free − - SiliconeFlat head strap − − FlatFlat otherframeface for Speedo that a watertight moves goggles with fit the andunun unexchangeableexchangeableexchangeable - UV protectionGoggles ($16.87) − − UVUV protection protection − Flat- Comfortable− − flex Comfortable frameComfortable that flex flex unexchangeable − UV protection −face forComfortable a watertight flex fit - Latex-free − − LatexLatex-free-free moves withframe theframe face that that formoves moves a with with the the − Latex-free − Dual head strap frame that moves with the watertight fitfaceface for for a awatertight watertight fit fit − Anti-fog −secures Dual goggle head firmly strap on face for a watertight fit − Interchange-able − UV protection head, for swimming or − Multi-colored Soft silicone seal nose clip Amanzi Axion − Anti-fog −secures Dual goggle head firmlystrap on − Interchange-able − Hydrodynamic diving− Dual head strap mirrored lens for − for comfort around − Nose clip comes 4 Mirrored Goggle −-− AntiDualUV- protectionfog head strap secures−head, Dualfor goggle swimming head firmly strap oron − Multi-colored Soft silicone seal - Interchange-able−nose Interchangeclip -able - Anti-fogAmanzi Axion design− Anti with-fog sleek lens −secures Easy goggle strap firmly on outdoor swimming, or the eye socket in− threeInterchange sizes for a- able −− AntiHydrodynamic-fog securesdiving- goggleMulti-colored firmly on −mirrored lens for − for comfort around − InterchangeNose clip comes-able 4 Mirrored($20.00) Goggle − UVsecuresUV protection protection goggle firmlyhead,head, for for swimming swimming or or − MultiSoftMulti- siliconecolored-colored seal SoftSoft silicone silicone seal seal nosenosenose clip clip clip - UV protectionAmanziAmanzi Axion Axion −designprofile UV withand protection minimalsleek lens drag head,−adjustment forEasy swimmingmirrored strap with dual lensor for−outdoorwell -litMulti indoor swimming,-colored pools or Softthe− eye siliconeprevents socket seal leakage noseincustomiz three clip sizes ed fit: for small, a Amanzi Axion Amanzi($20.00) Axion − − HydrodynamiconHydrodynamic head, for divingdiving mirroredmirrored lens lens for for − − forfor comfort comfort around around- Nose− − clipNoseNose comes clip clip comes incomes - 4Hydrodynamic 4 MirroredMirrored Goggle Goggle design −profile− HydrodynamicSilicone/Plastic and minimal drag divingadjustmenthook clip outdoorto with tighten dual or mirroredwell-lit- indoor lensfor for pools comfort around− forprevents the comfort leakage around −customizmedium, Noseed large clip fit: small,comes 4 Mirrored Goggle 4 Mirrored Goggle designdesignswimming with with sleek sleek lens orlens diving − − EasyEasy strap strap outdooroutdoor swimming, swimming, or or thethe eye eye socket socket threeinin three three sizes sizes sizes for for a for a a with sleek($20.00)($20.00) lens profile design− Silicone/Plastic with sleek lens −hookloosen. clipEasy swimming,to strap tighten or or outdoor swimming,eye socket or the eye socket inmedium, three sizes large for a ($20.00) profile- profileEasy and and minimal strapminimal adjustment drag drag adjustmentadjustment with with dual dual wellwell-lit-lit indoor indoor pools pools − − preventsprevents leakage leakage customizedcustomizcustomizeded fit:fit: fit: small, small, ($20.00) and minimal drag profile and minimal drag adjustmentloosen. well-lit with dual well-lit- indoorprevents pools leakage− prevents leakage customized fit: small, − − Silicone/PlasticwithSilicone/Plastic dual hook clip tohookhook clip clip to to tighten tighten or or small,medium,medium, large large - Silicone/Plastic − Silicone/Plastic hook clip toindoor tighten pools or medium, large tighten or loosen. loosen.loosen. medium, large Sporti Antifog loosen.− Plastic/rubber − Clear- Blue in − Made of rubber − Fixed and 5 SportiCabo Mirrored Antifog − Anti-fog − Plastic/rubberAdjustable −irregular Clear shape- Blue in −connected Made to of strap rubber −unexchangeable Fixed and Goggle ($6.95) − − Double strap 5 SportiCabo AntifogMirrored - PlasticAnti-fog/rubber − Plastic/rubberAdjustable Sporti Antifog Sporti Antifog − - Plastic/rubberClear- Blue in −irregular Clear- shape- BlueMade in of rubber−connected connectedMade toof straprubber - Fixed−unexchangeable Fixed and SportiGoggle Antifog ($6.95) − −− Plastic/rubberDouble strap − Clear- Blue in − Made of rubber − Fixed and 5 Cabo Mirrored - 5Anti-fog 5 CaboCabo Mirrored Mirrored - − AntiAdjustableAnti-fog-fog − AdjustableAdjustable − Clear- Blue in − Made of rubber − Fixed and 5 Cabo Mirrored − Anti-fog − Adjustableirregular shapeirregularirregular shape shapeto strap connectedconnected to to strap strap andunexchangeableunexchangeable unexchangeable Goggle ($6.95) GoggleGoggle ($6.95) ($6.95) - Double strap − − DoubleDouble strap strap irregular shape connected to strap unexchangeable Goggle ($6.95) − Double strap

Electronics 2020, 9, 992 4 of 20

Table 1. Cont. Electronics 2020, 9, 992 6 of 20 No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image

No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image - ElectronicsAnti-fog 2020, 9, 992 6 of 20 − Anti-fog - Orbit-Proof - Wide − Orbit-Proof − Wide poly- ElectronicsTechnologyNo 2020, Model9 provides, 992 - Anti-fogFeatures − Strap/MaterialAntipoly-carbonate-fog Lens Frame/Gaskets Nose Bridge Image 6 of 20 Technology provides carbonate- lensesSmart − Smart one-piece watertight fit around -− 50%Anti- Polycarbonate,fog − 50%lenses shaped for - Fixed Arena The One Jr. Arena The One Jr. watertight fit around the shaped for forwardone-piece constructionconstruction − Fixed and 6 ElectronicsNo6 2020, Model9, 992 − OrbitFeatures-Proof Polycarbonate,Strap/Materialforward 30% and − WideLens poly - Frame/Gaskets Nose Bridge Image 6 of 20 Goggle ($18.00) the eyeGoggle socket ($18.00) eye socket30% Thermoplastic − Anti-fog and peripheral − embedded lenses andunexchangeable unexchangeable Technology− Anti-fog provides Thermoplasticperipheral Rubber, visibility carbonate- lensesembedded lenses− Smart and clips one-piece - Seals avoid zones on − Rubber,Seals avoid 20% zones Silicone on − 50% visibility and clips Arena The One Jr. watertight− Orbit fit-Proof around the 20% Silicone shaped− Wide for forward poly- construction − Fixed and anyNo6 face thatModel any face thatFeatures compromise Polycarbonate,− - Strap/MaterialAntiClear-fog 30% - pink − ClearLens - pink Frame/Gaskets Nose Bridge Image Goggle ($18.00) eyeTechnology socket provides andcarbonate peripheral lenses − embeddedSmart one- piecelenses unexchangeable compromise suction suction− Anti -fog Thermoplastic− 50% Rubber, Arena The One Jr. −watertight Seals fitavoid around zones the on visibilityshaped for forward andconstruction clips − Fixed and 6 − Orbit-Proof 20%Polycarbonate,− SiliconeComes pre 30%- − Wide poly- Goggle ($18.00) anyeye socketface that compromise − Anti-fog −and peripheralClear - pink − embedded lenses unexchangeable Technology provides Thermoplasticassembled with Rubber, Latex carbonate lenses − Smart one-piece Sporti Antifog suction− Seals avoid zones on − 50% visibility and clips Arena The One Jr. - watertightComes fit pre-assembledaround the 20%strap Silicone −shaped Mirrored for forward lenses construction − Fixed and 6 Swedish Mirrored any− faceAnti that-fog compromise −Polycarbonate, Comes pre 30%- − Clear - pink − Fixed and 7 Goggle ($18.00) eye socketwith Latex strap − Additional black toand further peripheral reduce glare − Oneembedded piece lenses unexchangeable Sporti Antifog Goggle + Bungee suction− UV Protection assembledThermoplastic- Mirrored with Rubber, Latex lenses to unexchangeable Sporti Antifog - − AdditionalSeals avoid zones black on bungee strap with toggle −visibility Flat and clips - Anti-fogStrap ($3.95) strap−20% SiliconeComesfurther pre- − Mirrored lenses - Fixed Swedish Mirrored Swedish Mirrored −any facebungeeAnti that-fog compromisestrap − Easily adjustable − -Clear One- pink piece − Fixed and 7 - UV7 Protection −assembled Additionalreduce with Latex black glare to further reduce glare − One piece and unexchangeable Goggle + Bungee GoggleSporti Antifog + Bungee −suction withUV Protection toggle to customize fit unexchangeable Strap ($3.95) bungeestrap- strapFlat with toggle − FlatMirrored lenses StrapSwedish ($3.95) Mirrored -− EasilyAntiG.O.- fogFit adjustable system to − Comes pre- − Fixed and 7 − EasilyAdditional adjustable black to further reduce glare − One piece Goggle + Bungee −offers customize UVa precision Protection fitfit with assembled with Latex unexchangeable Sporti Antifog tobungee customize strap fitwith toggle − Flat StrapSpeedo ($3.95) the sleek, low-profile inner −strap Rubber double − Mirrored lenses − Four (4) Swedish Mirrored −− G.O.Anti -Fitfog system − Easily adjustable − Black − Fixed and 87 Vanquisher EV eye fit. strap− Additional black to further reduce glare − SoftOne siliconepiece gaskets interchangeable nose Goggle + Bungee offers− aUV precision Protection fit with to customize fit − Flat unexchangeable - G.O. FitGoggle system ($21.99) offers − 20% more functional −bungee Adjustable strap with toggle − Flat pieces SpeedoStrap ($3.95) the− sleek,G.O. low Fit- profilesystem inner − Rubber double − Four (4) a precision fit with the optical surface than its − Easily adjustable − Black 8 Vanquisher EV eyeoffers fit. a precision fit with strap − Soft silicone gaskets interchangeable nose sleek, low-profile predecessor to customize fit − Flat - Four (4) Speedo GoggleSpeedo ($21.99) -−the sleek,Rubber20% low more- doubleprofile functional inner strap − - AdjustableRubberBlack double pieces− Four (4) inner eye fit. − AntiG.O.- fogFit system − Black- Soft silicone gaskets interchangeable 8 Vanquisher EV 8 Vanquisher EV -opticaleye fit.Adjustable surface than its strap− - Straps/Gasket:Flat − SoftEasy silicone 90 degree gaskets interchangeable− Includes 2 nosesizes −offers Enhanceda precision peripheral fit with − FlatRubbing inside nose pieces Goggle ($21.99) - 20% moreGoggle functional ($21.99) predecessor− 20% more functional −100% AdjustableSilicone locking system, for a piecesof interchange -able Speedo visionthe sleek, low-profile inner − Rubber double lens will damage the − Four (4) optical surface than −optical Anti surface-fog than its − Double Silicone − Black secure and nose pieces for custom 8 SportiVanquisher Antifog EV S3 −eye fit.UV Shield −strap Straps/Gasket: antifog performance −− EasySoft silicone90 degree gaskets −interchangeable Includes 2 sizesnose its predecessor −predecessor Enhanced peripheral thin straps −− RubbingFlat inside reliable fit fit 9 MirroredGoggle ($21.99) Goggle − Low20% -moreprofile functional design 100%− SiliconeAdjustable − Shatter-resistant, locking system, for a ofpieces interchange -able vision− Anti -fog − Back buckle lens will damage the − Lightly Softeril® − Improved nose ($7.95) −optical Hypo surface-allergenic than its − DoubleStraps/Gasket: Silicone polycarbonate lenses secure− Easy and 90 degree nose− piecesIncludes for 2custom sizes Sporti Antifog S3 − UVEnhanced Shield peripheral distributes pressure antifog− Rubbing performance inside gasket than S2 goggle for bridge design, to - Anti-fog (Latexpredecessor and PVC Free) thin100% straps Silicone − Lens: 100% Poly- reliablelocking fitsystem, for a fitof interchange-able 9 Mirrored Goggle −vision Low -profile design evenly- forRubbing a comfortable inside −lens willShatter dam-ageresistant, the improved ® prevent contact with -− StrapsDynamicAnti-fog/Gasket: cuts to help − BackDouble buckle Silicone carbonate −secure Lightly and Softeril- Includes−nose piecesImproved 2 sizes for ofcustom nose - Enhanced($7.95)Sporti Antifog S3 − HypoUV Shield-allergenic fit− Straps/Gasket:lens will damage polyantifog- carbonate performance lenses extended− Easy comfort 90 degree user’s− Includesnose 2 sizes slice− through100%Enhanced Silicone water peripheral distributesthin straps pressure − Rubbing- Easy inside 90 degreegasketreliable locking than fit S2 goggle for interchange-ablebridgefit design, to peripheral9 Mirrored vision Goggle (Latex− Low and- PVCprofile Free) design 100% Siliconethe − Lens:Shatter 100%-resistant, Poly- locking system, for a of interchange-able - visionDouble Silicone evenly− Back for a buckle comfortable lens− willPetrol dam system,coloredage the for aimproved−secure Lightly Softeril® noseprevent− piecesImproved contact for withnose - UV Shield($7.95) −− DynamicHypoAnti-fog-allergenic cuts to help − Doubleantifog Silicone performance carbonatepoly- carbonate lenses secure and nose pieces for custom Sporti Antifog S3 Sporti Antifog S3 − thinUV Shield straps fitdistributes− Adjustable pressure straps antifogpolarized performance lensesandreliable fitextendedgasket than comfort S2 goggle for customuser’sbridge fitnose design, to 9 Mirrored Goggle - Low-profileZone 3 designVapour slice(Latex− through Extremelyand PVC water Free) soft and thin- strapsShatter-resistant, − Lens: 100% Poly- reliable® fit fit 9 Mirrored Goggle - − BackLow- buckleprofile design evenlywith twin for apiece comfortable head −curved Shatter- to ensureLightly-resistant, Softeril improved− gasketUltra -soft than eye pieces-® Improvedprevent− Fixed contact nose and with - Hypo-allergenic10 Polarized Revo −flexible Dynamic cuts to help − Backpoly- buckle carbonate− Petrol colored − Lightly Softeril − Improved nose ($7.95) ($7.95) −− distributesAntiHypo-fog-allergenic pressure fitstraps for a supportive polysuperior- carbonate S2 goggle lenses forextendedwith improved flexible comfort silicone. bridgeuser’sunexchangeable design, nose to (LatexGoggles and PVC ($45.00) Free) slice− through100% UVA/UVB water −distributes Adjustablecarbonate pressure straps lenses polarized lenses gasket than S2 goggle for bridge design, to Zone 3 Vapour −(Latex evenlyExtremely and PVC for Free)soft a and fit −vision Lens: in both 100%extended light Poly - comfort prevent contact protection withevenly- twin for Lens:piece a comfortable head curved− Petrol to ensure colored −improved Ultra -soft eye pieces −prevent Fixed contact and with - Dynamic10 Polarized cuts to Revo help flexible− comfortableAntiDynamic -fog cuts fit to help carbonateand dark conditions with user’s nose straps−fit Adjustable for 100%a supportive Poly-carbonate straps superiorpolarized lenses withextended flexible comfort silicone. unexchangeableuser’s nose slice throughGogglesZone 3 Vapour water($45.00) −slice through100%Extremely UVA/UVB water soft and fitwith twin piece head visioncurved in to both ensure light − Ultra-soft eye pieces − Fixed and 10 Polarized Revo protectionflexible − Petrol colored − Anti-fog straps for a supportive andsuperior dark conditions with flexible silicone. unexchangeable Goggles ($45.00) − 100% UVA/UVB − Adjustable straps polarized lenses Zone 3 Vapour − Extremely soft and fit vision in both light protection with twin piece head curved to ensure − Ultra-soft eye pieces − Fixed and 10 Polarized Revo flexible and dark conditions straps for a supportive superior with flexible silicone. unexchangeable Goggles ($45.00) − 100% UVA/UVB fit vision in both light protection and dark conditions

Electronics 2020, 9, 992 6 of 20

No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image − Anti-fog − Orbit-Proof − Wide poly- − Anti-fog Technology provides carbonate lenses − Smart one-piece − 50% Arena The One Jr. watertight fit around the shaped for forward construction − Fixed and 6 Polycarbonate, 30% Goggle ($18.00) eye socket and peripheral − embedded lenses unexchangeable Thermoplastic Rubber, − Seals avoid zones on visibility and clips 20% Silicone any face that compromise − Clear - pink suction − Comes pre- assembled with Latex Sporti Antifog strap − Mirrored lenses Swedish Mirrored − Anti-fog − Fixed and 7 − Additional black to further reduce glare − One piece Goggle + Bungee − UV Protection unexchangeable bungee strap with toggle − Flat Strap ($3.95) − Easily adjustable to customize fit − G.O. Fit system offers a precision fit with Speedo the sleek, low-profile inner − Rubber double − Four (4) − Black 8 Vanquisher EV eye fit. strap − Soft silicone gaskets interchangeable nose − Flat − − Goggle ($21.99) 20% more functional Adjustable pieces optical surface than its predecessor − Anti-fog − Straps/Gasket: − Easy 90 degree − Includes 2 sizes Electronics 2020, 9, 992 − Enhanced peripheral − Rubbing inside 5 of 20 100% Silicone locking system, for a of interchange-able vision lens will damage the − Double Silicone secure and nose pieces for custom Sporti Antifog S3 − UV Shield antifog performance thin straps reliable fit fit 9 Mirrored Goggle − Low-profile design − Shatter-resistant, − Back buckle − Lightly Softeril® − Improved nose ($7.95) − Hypo-allergenic Table 1. Cont.polycarbonate lenses distributes pressure gasket than S2 goggle for bridge design, to (Latex and PVC Free) − Lens: 100% Poly- evenly for a comfortable improved prevent contact with No Model Features− Dynamic Strap/Material cuts to help Lenscarbonate Frame/Gaskets Nose Bridge Image fit extended comfort user’s nose slice through water - Petrol colored − Petrol colored - Anti-fog − Anti-fog − Adjustablepolarized straps lenses polarized lenses Zone 3 Vapour - ExtremelyZone soft 3 Vapour -− AdjustableExtremely soft straps and with with twincurved piece head to ensurecurved- to ensureUltra-soft eye− piecesUltra with-soft eye pieces- Fixed− Fixed and 10 Polarized Revo and10 flexiblePolarized Revo flexibletwin piece head straps straps for superiora supportive vision insuperior flexible silicone.with flexible silicone. andunexchangeable unexchangeable Goggles ($45.00) - 100% Goggles ($45.00) − for100% a supportive UVA/UVB fit fit both light and vision in both light UVA/UVB protection protection Electronics 2020, 9, 992 dark conditions and dark conditions 7 of 20

ElectronicsNo 2020,Model 9, 992 Features Strap/Material Lens Frame/Gaskets Nose Bridge Image 7 of 20 - Anti-fog − Anti-fog − Wide panoramic - ElectronicsRetains 2020 classic, 9, 992 Speedo 7 of 20 No Model − RetainsFeatures classic Strap/Material - LensWide panoramicvision vision Frame/Gaskets Nose Bridge Image Speedo Speed SocketSpeedo fit, but Speed also Speedo Socket fit, but also − Inner Eye: - − DoubleAnti-fog head strap − - DoubleMirrored head strap lens − Mirrored- Inner lens Eye: − Wide panoramic Socket 2.0 oNoffers Socket increase Model2.0 offers increaseFeatures peripheral Strap/Material Lens - ProvidesFrame/Gaskets a precision- Fixed− FixedNose Bridgeand Image 11 11 − ensuresRetains classic a secure fit ensures a securereduces fit glare reduces- glareProvides and a precisionvision fit Mirrored Goggle peripheralMirrored vision Goggle vision− Anti-fog fit− Wide panoramic andunexchangeable unexchangeable Speedo Speed - SpeedoLatex-free Socket fit, but also − Latexand-free brightness brightness- The gasket rests− snuglyInner Eye: and ($31.99) - Hypo-allergenic($31.99) −− HypoRetains-allergenic classic − Double head strap − Mirrored lens -vision The gasket rests Socket 2.0 offers increase peripheral securely on the- eyeProvides socket. a precision − Fixed and comfort11 Speedo seals Speed comfortSpeedo sealsSocket fit, but also ensures a secure fit reduces glare and snugly− Inner and securely Eye: on the Mirrored Goggle vision − Double head strap − Mirrored lens fit unexchangeable - UV protectionSocket 2.0 −offers UV increase protection peripheral − Latex-free brightness eye- socket.Provides a precision − Fixed and 11 ($31.99) − Hypo-allergenic ensures a secure fit reduces glare and - The gasket rests Mirrored Goggle −vision Unparalleled clarity fit unexchangeable comfort seals − Latex-free brightness snugly and securely on the ($31.99) −− ComesHypo- allergenicin a - The gasket rests − UV protection − Three eye socket. - Unparalleled clarity protectivecomfort seals Brownlee case snugly and securely on the − Triple Huub Brownlee − Unparalleled clarity interchangeable split - Comes12 in a protective with− twoUV additional protection straps − Mirrored lens −eye socket.N/A interchange-able nose Goggle ($48.95) - − ThreeComes interchangeable in a straps for comfort and - Triple Brownlee casewith as− a tributeUnparalleled to clarity − Three bridge for optimum fit protectivesplit strapsBrownlee for case facial pressure reduction interchange-able− Triple Huub Brownlee two additionalHuub Brownlee straps the− brotherComes 2016 in aOlympic interchangeable- Mirrored split lens -N /A 12 12 with comforttwo additional and facial straps − Three − Mirrored lens − N/A noseinterchange bridge for-able nose Goggle ($48.95) as a tributeGoggle to ($48.95) the victoriesprotective Brownlee case straps for comfort and − Triple Huub Brownlee as a tributepressure to reduction interchangeable split optimumbridge for fit optimum fit brother12 2016 with two additional straps facial pressure reduction − Mirrored lens − N/A interchange-able nose Goggle ($48.95) −the brotherAnti-fog 2016 Olympic −straps Speedo for comfort Fit clips and − Flexible gaskets for Olympic victories as a tribute to bridge for optimum fit Speedo Futura −victories Biofuse technology forfacial easy, pressure precise reduction − Curved lens for added comfort and the brother 2016 Olympic Biofuse Flexiseal − UV protected lenses adjustment optimal peripheral reduced pressure around − Fixed and 13 victories− Anti -fog − Speedo Fit clips − Flexible gaskets for Mirrored Goggle block the sun’s − Soft silicone head vision eyes unexchangeable - Anti-fogSpeedo Futura - − SpeedoBiofuse Fittechnology clips for for easy, precise − Curved lens for added comfort and ($27.99)Biofuse Flexiseal harmful− AntiUV UVA protected-fog and UVB lenses strap−adjustment Speedo Fit clips −optimal Mirrored- peripheralFlexible lens gaskets−−reduced forSoftFlexible added pressure unibody gaskets around frame for − Fixed and - Biofuse13 technology easy, - Curved lens for Speedo Futura Speedo Futura rays− Biofuse technology −for− easy,Latex precise-free − Curvedcomfort lens for and −added reduced Outer comfort eye andfit Mirrored Goggle blockprecise the sun adjustment’s Softoptimal silicone head vision eyes unexchangeable Biofuse Flexiseal - UV protectedBiofuse Flexiseal lenses − UV protected lenses adjustment optimal peripheralpressure aroundreduced eyes pressure around- Fixed− Fixed and 13 13 ($27.99) −harmful Anti UVA-fog and UVB strap − Mirrored lens − Soft unibody frame Mirrored Goggle block theMirrored sun’s Goggle - blockSoft the sun silicone’s − Softperipheral silicone head vision vision eyes andunexchangeable unexchangeable −rays Developed as part of − Latex-free - Soft unibody− frame Outer eye fit ($27.99) harmful($27.99) UVA and harmfulhead UVA strap and UVB strap- Mirrored lens − Mirrored lens − Soft unibody frame the world’s first Racing - Outer eye fit UVB rays - rays− Latex-freeAnti-fog − Latex-free − Outer eye fit System,− Developed engineering as cap,part of − IQ Fit goggle strap − Hydroscopic goggles,− Anti and-fog suit to work is fully integrated one Lens is a unique Speedo Fastskin the world’s first Racing in− harmonyDeveloped as part of piece strap which lens shape offering an − Fixed and 14 Elite Mirrored System, engineering cap, − IQ Fit goggle strap − Hydroscopic − N/A −the worldSpeedo’s first’s first Racing true eliminates dangling increased field of unexchangeable Goggle ($75.00) goggles, and suit to work is fully integrated one Lens is a unique Speedo Fastskin 3DSystem, goggle engineering seal designed cap, strap− endsIQ Fit goggle strap vision− Hydroscopic in harmony piece strap which lens shape offering an − Fixed and 14 Elite Mirrored forgoggles, real head and and suit face to work −is fullyLatex integrated-free one −Lens Mirroredis a unique lens − N/A Speedo Fastskin − Speedo’s first true eliminates dangling increased field of unexchangeable Goggle ($75.00) contoursin harmony piece strap which lens shape offering an − Fixed and 14 Elite Mirrored 3D goggle seal designed strap ends vision − N/A −− ImprovedSpeedo’s firstseal trueleak eliminates dangling increased field of unexchangeable Goggle ($75.00) for real head and face − Latex-free − Mirrored lens resistance3D goggle seal designed strap ends vision contours for− realImproved head and seal face leak − Latex-free − Mirrored lens contoursresistance − Improved seal leak resistance

Electronics 2020, 9, 992 7 of 20

No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image − Anti-fog − Wide panoramic − Retains classic vision Speedo Speed Speedo Socket fit, but also − Inner Eye: − Double head strap − Mirrored lens Socket 2.0 offers increase peripheral - Provides a precision − Fixed and 11 ensures a secure fit reduces glare and Mirrored Goggle vision fit unexchangeable − Latex-free brightness ($31.99) − Hypo-allergenic - The gasket rests comfort seals snugly and securely on the − UV protection eye socket. − Unparalleled clarity − Comes in a − Three protective Brownlee case − Triple Huub Brownlee interchangeable split 12 with two additional straps − Mirrored lens − N/A interchange-able nose Goggle ($48.95) straps for comfort and as a tribute to bridge for optimum fit facial pressure reduction Electronics 2020, 9, 992 the brother 2016 Olympic 6 of 20 victories

− Anti-fog − Speedo Fit clips − Flexible gaskets for Speedo Futura − Biofuse technology for easy, preciseTable 1. Cont.− Curved lens for added comfort and Biofuse Flexiseal − UV protected lenses adjustment optimal peripheral reduced pressure around − Fixed and 13 − No Model FeaturesMirrored Goggle block the Strap sun/’Materials Soft silicone Lens head vision Frame/Gasketseyes Noseunexchangeable Bridge Image ($27.99) harmful UVA and UVB strap − Mirrored lens − Soft unibody frame rays − Latex-free − Outer eye fit - Anti-fog - Developed as part of − Anti-fog the world’s first − Developed as part of Racing System, the world’s first Racing - IQ Fit goggle strap is - Hydroscopic Lens engineering cap, System, engineering cap, − IQ Fit goggle strap − Hydroscopic fully integrated one is a uniquelens goggles, and suit to goggles, and suit to work is fully integrated one Lens is a unique Speedo Fastskin Speedo Fastskin piece strap which shape offering an - Fixed work in harmony in harmony piece strap which lens shape offering an − Fixed and 14 Elite Mirrored 14 Elite Mirrored -N /A − N/A − eliminatesSpeedo’s first dangling true eliminates increaseddangling field increased field of andunexchangeable unexchangeable Goggle ($75.00) - Speedo’sGoggle first ($75.00) true 3D strap ends of vision goggle seal designed 3D goggle seal designed strap ends vision - Latex-free - Mirrored lens for real head and for real head and face − Latex-free − Mirrored lens face contours contours - Improved seal − Improved seal leak resistance Electronicsleak resistance 2020, 9, 992 8 of 20

ElectronicsNo 2020,Model 9, 992 Features Strap/Material Lens Frame/Gaskets Nose Bridge Image 8 of 20 - Anti-fog & anti scratch − Anti-fog & anti - Exo-CoreNo technology,Model scratch Features Strap/Material Lens Frame/Gaskets Nose Bridge Image combining two −− ExoAnti-Core-fog & anti - Anatomical− gaskets: Anatomical For gaskets: materials for technology,scratch combining - Quick-adjusting, comfort andFor feel comfort and feel maximum performance two− materialsExo-Core for − Quick-adjusting, hydrophobic, and - Curved lens − Curved- Semi-rigid lens exoskeleton−− SemiAnatomical-rigid gaskets: - Developed with maximumtechnology, performance combining hydrophobic, and low- MP Michael low-profile techno-logy: Wide,techno-logy: maximizesWide, theexoskeletonFor structure, comfort maximizes and feel- the Ergonomic,− Ergonomic, MP Michael Michael Phelps −two materialsDeveloped for with profile− Quickhead buckle-adjusting, 15 Phelps Xceed head buckle peripheral visionperipheral− Curved visionstrength, lens andstructure,−stability Semi strength, of-rigid and interchangeableinterchangeable nose 15 Phelps Xceed andBob Bowman Michaelmaximum Phelps performance and −hydrophobic, Silicone, andlow -low- GoggleMP Michael ($16.87) - Silicone, low-profile - −t echnoPoly-logy:-carbonatethe Wide, goggle stabilityexoskeleton of the maximizes goggle thenose bridge− bridge Ergonomic, Goggle ($16.87) - Expanded field of Bob− BowmanDeveloped with profileprofile strap: head Forbuckle ideal 15 Phelps Xceed strap: For ideal grip Poly-carbonate lenseslensesperipheral - visionUltra-soft Softeril−structure, ®Ultragasket: strength,-soft Softeril and® interchangeable nose vision allows the −Michael Expanded Phelps andfield of grip− andSilicone, easy adjust low- Goggle ($16.87) and easy adjust − Poly-carbonate gasket:stability For of athe water goggle-tight bridge visionBob Bowman allows the swimmer profile strap: For ideal For a water-tight seal swimmer to sight lenses seal− andUltra comfort-soft Softeril® to− sightExpanded walls and field the of grip and easy adjust and comfort walls and the gasket: For a water-tight competitionvision allows without the swimmer competition without seal and comfort altering head position alteringto sight headwalls position and the competition without − Head strap − TPR frame/gasket altering head position features Glide Clip features dual injected system− Head which strap allows - Head strap features system− TPR with frame/gasket over-molded easyfeatures on-head Glide Clip − Wide peripheral Glide Clip system nosefeatures bridge dual injected − Anti-fog adjustmentsystem which allows Cellulose- PropionateTPR frame /gasket features TYR Nest Pro which allows easy - Wide peripheral −system Polyp withropylene over-molded over- − Tight fit −easy onDouble-head VTS (CP)− lensesWide feature dualperipheral injected system with − Over-molded 16 Swim Goggle on-head adjustment Cellulose moldnose nestbridge frame provides - Anti-fog −− NestAnti -Framefog (Variedadjustment Tensile embeddedCellulose Propionate antifogover-molded nose bridge nose bridge TYR Nest Pro ($13.59)TYR Nest Pro - Double VTS (Varied Propionate (CP) unique− Polyp high-ropylenetech structure over- - Tight fit Technology− Tight fit Strength)− Double silicone VTS head properties(CP) lenses- and featurePolypropylene are UV over-mold - Over-molded− Over-molded 16 Swim Goggle 16 Swim Goggle Tensile Strength) lenses feature designmold nest frame provides - Nest − Nest Frame strap(Varied conforms Tensile to side of protectedembedded antifognest frame provides unique nosenose bridge bridge ($13.59) ($13.59) silicone head strap embedded antifog −unique Soft high TPR-tech gaskets structure for Frame Technology Technology headStrength) while silicone flat back head properties andhigh-tech are UV structure design conforms to side of properties and are comfortable,design water-tight strapsstrap conformsallow for secureto side of protected- Soft TPR gaskets for head while flat back UV protected fit− Soft TPR gaskets for fithead while flat back comfortable, water-tight fit straps allow for comfortable, water-tight − Anti-fog straps allow for secure Speedo secure fit fit − UV protection fit Vanquisher − Polycarbonate − Interchangeable 17 −− AvailableAnti-fog in − N/A − N/A OpticalSpeedo Goggle lens nosepiece negative− UV diopters protection −1.5 to ($21.99)Vanquisher − Polycarbonate − Interchangeable 17 −8− Available in − N/A − N/A Optical Goggle lens nosepiece −negative Anti diopters-fog −1.5 to ($21.99) −−8 Sleek, low-profile TYR Tracer design− Antireduces-fog drag − Adjustable head − Includes five − PC lens 18 Racing Metallized −− ImprovedSleek, low light-profile strap with glide clip − Soft TPR gaskets nose bridges for − Spherical shape GoggleTYR Tracer ($10.69) absorptiondesign reduces and peripheral drag system− Adjustable head custom− Includes fit five − PC lens 18 Racing Metallized vision− Improved light strap with glide clip − Soft TPR gaskets nose bridges for − Spherical shape Goggle ($10.69) −absorption UV protection and peripheral system custom fit vision − UV protection

Electronics 2020, 9, 992 8 of 20 Electronics 2020, 9, 992 8 of 20 No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image No Model − AntiFeatures-fog & anti Strap/Material Lens Frame/Gaskets Nose Bridge Image −scratch Anti -fog & anti − Exo-Core scratch − Anatomical gaskets: technology, combining − Exo-Core For comfort and feel two materials for − Quick-adjusting, − Anatomical gaskets: technology, combining − Curved lens − Semi-rigid maximum performance hydrophobic, and low- For comfort and feel MP Michael two materials for − Quick-adjusting, techno-logy: Wide, exoskeleton maximizes the − Ergonomic, − Developed with profile head buckle − Curved lens − Semi-rigid 15 Phelps Xceed maximum performance hydrophobic, and low- peripheral vision structure, strength, and interchangeable nose MP Michael Michael Phelps and − Silicone, low- techno-logy: Wide, exoskeleton maximizes the − Ergonomic, Goggle ($16.87) − Developed with profile head buckle − Poly-carbonate stability of the goggle bridge 15 Phelps Xceed Bob Bowman profile strap: For ideal peripheral vision structure, strength, and interchangeable nose Michael Phelps and − Silicone, low- lenses − Ultra-soft Softeril® Goggle ($16.87) − − Poly-carbonate stability of the goggle bridge Bob BowmanExpanded field of profilegrip and strap: easy For adjust ideal lenses −gasket: Ultra For- asoft water Softeril-tight® −vision Expanded allows the field swimmer of grip and easy adjust gasket:seal and For comfort a water -tight visionto sight allows walls theand swimmer the seal and comfort tocompetition sight walls without and the competitionaltering head without position − Head strap altering head position − TPR frame/gasket features Glide Clip − Head strap features dual injected system which allows − TPR frame/gasket features Glide Clip system with over-molded easy on-head − Wide peripheral features dual injected system which allows nose bridge Electronics 2020, 9, 992 − Anti-fog adjustment Cellulose Propionate system with over-molded 7 of 20 TYR Nest Pro easy on-head − Wide peripheral − Polypropylene over- − Tight fit − Double VTS (CP) lenses feature nose bridge − Over-molded 16 Swim Goggle − Anti-fog adjustment Cellulose Propionate mold nest frame provides TYR Nest Pro − Nest Frame (Varied Tensile embedded antifog − Polypropylene over- nose bridge ($13.59) − Tight fit − Double VTS (CP) lenses feature unique high-tech structure − Over-molded 16 Swim Goggle Technology Strength) silicone head properties and are UV mold nest frame provides − Nest Frame (VariedTable Tensile 1. Cont. embedded antifog design nose bridge ($13.59) strap conforms to side of protected unique high-tech structure Technology Strength) silicone head properties and are UV − designSoft TPR gaskets for straphead conformswhile flat toback side of protected No Model Features Strap/Material Lens Frame/−Gasketscomfortable, Soft TPR water gaskets-tight for Nose Bridge Image headstraps while allow flat for back secure comfortable,fit water-tight strapsfit allow for secure Speedo - Anti-fog − Anti-fog fit Speedo fit Vanquisher - UV protection − UV protection - 17 Vanquisher -N− /AntiA- -fogPolycarbonate lens-N − Polycarbonate/A − Interchangeable Optical Goggle - Available17 Speedo in negative − Available in − N/A − N/A Interchangeable nosepiece Optical Goggle − UV protection lens nosepiece dioptersVanquisher1.5 to 8 − Polycarbonate − Interchangeable ($21.99) 17 −negative Available diopters in −1.5 to − N/A − N/A Optical($21.99)− Goggle − lens nosepiece negative−8 diopters −1.5 to ($21.99) −8− Anti-fog - Anti-fog − − AntiSleek,-fog low -profile - Sleek, low-profileTYR Tracer design reduces drag − Adjustable head − Includes five − Sleek, low-profile − PC lens 18 Racing Metallized − Improved light strap with glide clip − Soft TPR gaskets nose bridges for TYR Tracer design reducesTYR Tracer drag design reduces drag − Adjustable head − - Includes− Includes five nose five - Adjustable head strap - PC lens − PCSpherical lens shape 18 Racing Metallized - Improved18 RacingGoggle light Metallized ($10.69) −absorption Improved and peripherallight strapsystem with glide clip - Soft TPR gaskets− Soft TPR gaskets bridgesnosecustom bridges forfit for with glide clip system - Spherical shape − Spherical shape Goggle ($10.69) absorptionGoggle and ($10.69) absorptionvision and peripheral system customcustom fitfit − peripheral vision vision UV protection - ElectronicsUV protection 2020, 9, 992 − UV protection 9 of 20

Electronics 2020, 9, 992 9 of 20 ElectronicsNo 2020Model, 9, 992 Features Strap/Material Lens Frame/Gaskets Nose Bridge Image 9 of 20 - Hypo-allergenic − Hypo-allergenic

comfortNoNo fit ModelModel comfort fitFeaturesFeatures Strap/MaterialStrap/Material LensLens Frame/GasketsFrame/Gaskets NoseNose Bridge Bridge ImageImage - Low-profile design −− LowHypoHypo-profile-allergenic-allergenic design - High− noseHigh bridgenose bridge Speedo Speed with greatSpeedo Speed - withcomfortcomfortSilicone great fit fit peripheral double length − Silicone double - Mirrored lenses to− Mirrored lenses withwith three sizes sizes 19 Socket Mirrored peripheral19 Socket vision Mirrored vision−− head LowLow strap-profile-profile for design design a more length head strap for a -N /A − N/A further reduce glareto further reduce glare includedincluded−− HighHigh for for nose nosea a custom bridge bridge Goggle ($17.57) - Shatter resistant,GoggleSpeedoSpeedo ($17.57)Speed Speed −withwith secure great Shattergreat peripheral fit.peripheral resistant, more−− secureSiliconeSilicone fit. double double −− MirroredMirrored lenses lenses customfitwithwith three three fit sizes sizes polycarbonate1919 SocketSocket Mirrored lensMirrored polycarbonatevisionvision lens with lengthlength head head strap strap for for a a −− N/AN/A toto further further reduce reduce glare glare includedincluded for for a a custom custom with UVGoggleGoggle protection ($17.57) ($17.57) & UV−− protectionShatterShatter resistant, resistant,& anti-fog moremore secure secure fit. fit. fitfit anti-fog protection protectionpolycarbonatepolycarbonate lens lens with with UVUV protection protection & & anti anti-fog-fog − Oversizedultra- Aqua Sphere protectionprotection − Hypoallergenic − 100% UV protection − One-touch, Quick- durable Plexisol® lens − Stabilizing nose ® Kayenne Goggle - − Oversizedultra- Softeril one-piece, Aqua Sphere 20 Aqua Sphere − Anti-fog Fit Buckle for simple for− 4-pointOversizedultra expanded - − Hypoallergenic® - Stabilizingbridge keeps nose fit secure - 100% UVSmokeAqua protection SphereLens - One-touch, Quick-Fit Oversizedultra-durable ® hydrodynamic− Hypoallergenic micro − 100% UV protection − One-touch, Quick- durable Plexisol- Hypoallergenic® lens Softeril − Stabilizing nose −− Scratch100% UV resistant protection lens adjustments− One-touch, Quick- anddurable 180-degree Plexisol lens ® bridgeand− comfortableStabilizing keeps fit nose Kayenne Goggle Kayenne Goggle ® Softeril ® one-piece, 20 - Anti-fog20 ($21.95)Kayenne Goggle − BuckleAnti-fog for Fit BucklePlexisol for simplelens for for 4-point expandedone-piece, frame hydrodynamicSofteril one-piece, bridge keeps fit secure Smoke Lens 20 Smoke Lens − Anti-fog Fit Buckle for simple visibilityfor 4-point expanded hydrodynamic micro securebridge keeps fit secure - Scratch resistantSmoke Lens lens − simple adjustments 4-point expanded and micro framehydrodynamic micro − ScratchScratch resistant resistant lens lens adjustmentsadjustments andand 180 180-degree-degree andandand comfortablecomfortable comfortable ($21.95) ($21.95)($21.95) 180-degree visibility −frameframe Fits adult faces - for visibilityvisibility small and medium faces, fits−− FitsFits adult adult faces faces - -for for Aqua Sphere − Anti-fog coating - Fits adult facesaroundsmallsmall -and and forthe medium smallmediumoutside offaces, faces, eye − Adjustable strap 21 Kaiman Goggle − Ultra violet (UV) − N/A and mediumsocketfitsfits faces, fits − N/A for custom fit - Anti-fogClearAquaAqua coating LensSphere Sphere ($17.94) protection−− AntiAnti -fog-fog coating coating around the−aroundaround outsideSuper the the of outside softoutside skirt of of eye eye Aqua Sphere - Adjustable strap for −− AdjustableAdjustable strap strap - Ultra2121 violetKaimanKaiman Goggle Goggle −− UltraUltra violet violet (UV) (UV) -N /A −− N/AN/A eye socketengineeredsocketsocket for comfort -N −−/ A N/AN/A 21 Kaiman Goggle custom fit forfor custom custom fit fit (UV) protectionClearClear Lens Lens ($17.94) ($17.94) protectionprotection - Super softand− skirt− watertightSuper engineeredSuper soft soft skirt skirt Clear Lens ($17.94) for comfortsealengineeredengineered and for for comfort comfort watertightand sealand watertight watertight − Anti-fog sealseal Arena Cobra Ultra − Hard lenses − Extra-wide vision − UV protection − Dual strap − Interchangeable 22 Mirror Goggle − Anti-fog − Mirrored − Forward vision Arena Cobra Ultra −− HydrodynamicAnti-fog − Silicone − Hard lenses − Extra-wide vision nose bridge ($60.00)Arena Cobra Ultra − UV protection − Dual strap −− PolycarbonateHard lenses −− TPEExtra -wide vision − Interchangeable 22 Mirror Goggle design− UV protection − Dual strap − Mirrored − Forward vision − Interchangeable 22 Mirror Goggle − Hydrodynamic − Silicone − Mirrored − Forward vision nose bridge ($60.00) − Hydrodynamic − Silicone − Polycarbonate − TPE nose bridge ($60.00) − Polycarbonate − TPE designdesign − Universal fit Nike Swim − Anti-fog − Six-way 23 − Latex split strap − Polished PC lens − TPE gasket Chrome ($7.20) −− UVUniversalUniversal protection fit fit adjustable nose piece NikeNike Swim Swim −− IdealAntiAnti- fog-forfog training −− SixSix-way-way 2323 −− LatexLatex split split strap strap −− PolishedPolished PC PC lens lens −− TPETPE gasket gasket ChromeChrome ($7.20) ($7.20) −− UVUV protection protection adjustableadjustable nose nose piece piece

−− IdealIdeal for for training training − Great for all face − Curved lens for FINIS Energy shapes 24 − Great for all face − Silicone strap reduced distortion and − Soft TPR frame − N/A Goggle (11.99) −− “SoGreat More for Can all face − Curved lens for FINIS Energy shapes optimal− Curved viewing lens for 24 FINIS Energy Swim”shapes − Silicone strap reduced distortion and − Soft TPR frame − N/A 24 Goggle (11.99) − “So More Can − Silicone strap reduced distortion and − Soft TPR frame − N/A Goggle (11.99) − “So More Can optimal viewing Swim” optimal viewing Swim”

ElectronicsElectronics 20202020,, 99,, 992992 99 ofof 2020 Electronics 2020, 9, 992 9 of 20

No Model FeaturesFeatures Strap/MaterialStrap/Material LensLens Frame/GasketsFrame/Gaskets Nose Bridge ImageImage No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image −− Hypo--allergenicallergenic − Hypo-allergenic comfortcomfort fitfit comfort fit −− LowLow--profileprofile designdesign − Low-profile design −− High nose bridge SpeedoSpeedo SpeedSpeed with great peripheral −− SiliconeSilicone doubledouble − High nose bridge Speedo Speed with great peripheral − Silicone double −− Mirrored lenses with threethree sizessizes 1919 SocketSocket MirroredMirrored visionvision lengthlength headhead strapstrap forfor aa − Mirrored lenses −− N/A with three sizes 19 Socket Mirrored vision length head strap for a toto furtherfurther reducereduce glareglare − N/A includedincluded forfor aa customcustom Goggle ($17.57) −− ShatterShatter resistant,resistant, more secure fit. to further reduce glare included for a custom Goggle ($17.57) − Shatter resistant, more secure fit. fitfit polycarbonatepolycarbonate lenslens withwith fit polycarbonate lens with UV protection & anti--fogfog UV protection & anti-fog protectionprotection protection −− Oversizedultra-- Aqua Sphere − Oversizedultra- −− Hypoallergenic Aqua Sphere −− 100%100% UVUV protectionprotection −− One--touch,touch, QuickQuick-- durabledurable PlexisolPlexisol®® lenslens − Hypoallergenic −− StabilizingStabilizing nosenose Kayenne Goggle − 100% UV protection − One-touch, Quick- durable Plexisol® lens SofterilSofteril®® oneone--piece,piece, − Stabilizing nose 2020 Kayenne Goggle −− Anti--fogfog FitFit BuckleBuckle forfor simplesimple forfor 44--pointpoint expandedexpanded Softeril® one-piece, bridgebridge keepskeeps fitfit securesecure 20 SmokeSmoke LensLens − Anti-fog Fit Buckle for simple for 4-point expanded hydrodynamichydrodynamic micro bridge keeps fit secure Smoke Lens −− ScratchScratch resistantresistant lenslens adjustmentsadjustments andand 180180--degreedegree hydrodynamic micro andand comfortablecomfortable ($21.95)($21.95) − Scratch resistant lens adjustments and 180-degree frameframe and comfortable ($21.95) visibilityvisibility frame visibility −− FitsFits adultadult facesfaces -- forfor − Fits adult faces - for smallsmall andand mediummedium faces,faces, small and medium faces, Electronics 2020, 9, 992 fitsfits 8 of 20 fits Aqua Sphere −− Anti--fogfog coatingcoating aroundaround thethe outsideoutside ofof eyeeye Aqua Sphere − Anti-fog coating −− Adjustable strap around the outside of eye 2121 Kaiman Goggle −− Ultra violet (UV) − Adjustable strap −− N/A socketsocket −− N/A 21 Kaiman Goggle − Ultra violet (UV) forfor customcustom fitfit − N/A socket − N/A Clear Lens ($17.94) protectionprotection for custom fit −− SuperSuper softsoft skirtskirt Clear Lens ($17.94) protection − Super soft skirt Table 1. Cont. engineeredengineered forfor comfortcomfort engineered for comfort andand watertightwatertight and watertight No Model Features Strap/Material Lens Frame/Gasketssealseal Nose Bridge Image seal Arena Cobra Ultra - Anti-fog −− Anti--fogfog - Hard lenses - Extra-wide vision Arena Cobra Ultra -− DualAnti-fog strap −− Hard lenses −− ExtraExtra--wide vision- Interchangeable 22 Mirror Goggle - UV protectionArena Cobra Ultra −− UV protection −− - DualMirrored strap − Hard- lensesForward vision− Extra-wide vision −− InterchangeableInterchangeable 2222 Mirror Goggle -− SiliconeUV protection − Dual strap −− Mirrored −− ForwardForward visionvision nose− bridgeInterchangeable ($60.00) - Hydrodynamic22 Mirror Goggle design −− Hydrodynamic −− - SiliconeSiliconePolycarbonate − Mirrored- TPE − Forward vision nosenose bridgebridge ($60.00)($60.00) − Hydrodynamic − Silicone −− PolycarbonatePolycarbonate −− TPETPE nose bridge ($60.00) designdesign − Polycarbonate − TPE design - Universal ﬁt −− Universal fit - Anti-fog − Universal fit - Six-way adjustable Nike Swim Nike Swim -−− LatexAnti--fogfog split strap- Polished PC lens- TPE gasket −− SixSix--way 23 2323 Nike Swim − Anti-fog −− LatexLatex splitsplit strapstrap −− PolishedPolished PCPC lenslens −− TPETPE gasketgasket nose− pieceSix-way Chrome ($7.20) - UV23 protectionChrome ($7.20) −− UV protection − Latex split strap − Polished PC lens − TPE gasket adjustableadjustable nosenose piecepiece Chrome ($7.20) − UV protection adjustable nose piece - Ideal for training −− IdealIdeal forfor trainingtraining − Ideal for training

−− Great for all faceface − Great for all face - Curved lens for −− Curved lens for - Great forFINISFINIS all EnergyEnergy shapesshapes − Curved lens for FINIS Energy 2424 FINIS Energy shapes −− SiliconeSiliconereduced strapstrap distortionreducedreduced distortiondistortion andand −− SoftSoft TPRTPR frameframe −− N/A 24 Electronicsface24 shapesGoggle 2020, 9 ,(11.99) 992 -−− Silicone“So“So MoreMore strap CanCan − Silicone strap reduced- distortionSoft TPR and frame− -NSoft TPR frame /A− N/A 10 of 20 Goggle (11.99) Electronics Goggle2020, 9 ,(11.99) 992 − “So More Can and optimaloptimal viewingviewing 10 of 20 - “So More Can Swim” Swim”Swim” optimal viewing Swim” optimal viewing No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image No Model Features Strap/Material Lens Frame/Gaskets Nose Bridge Image

- ﬂared silicone seals - Anti-fog solution for − flared silicone seals- Four diﬀerent nose Zoggs Racepex Zoggs Racepex -− QuickAnti-fog adjust solution strap for- N /A for comfort − flared silicone seals − Four different 25 clear25 visionZoggs Racepex − Anti-fog solution for − Quick adjust strap − N/A for comfort bridge− sizesFour different Goggle ($9.75) 25 Goggle ($9.75) clear vision − Quick adjust strap − N/A- Adjustable framefor comfort nose bridge sizes Goggle ($9.75) clear vision − Adjustable frame nose bridge sizes − Adjustable frame

− Curved Smoke − - IntegratedCurved strap − Curved Smoke MP Michael -− IntegratedK 180 version strap loop − lens − Ultra-soft gasket: − Three MP Michael - K 180 version goggles: loop toIntegrated helpSmoke it stay strap lens - Ultra-soft gasket: 100% MP Michael − K 180 version lens − Ultra-soft® gasket:- Three− Three Phelps K-180 Phelps K-180 goggles:to help180 degrees it of loop to help it stay − Anatomic lens® 100% Softeril material for interchange-able nose 18026 degreesPhelps ofK-180 goggles: 180 degrees of hydrodynamic- Anatomic lens − AnatomicSofteril lens material100% Softeril for a leak® material for interchange-ableinterchange-able nose 26 Goggle 26 Goggle Smoke panoramicstay hydrodynamicvision hydrodynamic shape for a a leak resistant and bridge pieces for the panoramicGoggle vision Smoke panoramic vision − Headshape strap foris easy a shape for a resistant anda leak resistant and nosebridge bridge pieces pieces for the SmokeLens Lens ($14.06) -− Head100% UV strap protection is easy to − Head strap is easy comfortable and comfortable seal right fit - 100% UVLens protection ($14.06) − 100% UV protection to adjust forcomfortable the right fit. and comfortable andcomfortable comfortable seal seal forright the rightfit fit adjust for the right fit.to adjust for the right fit. water-tight fit ($14.06) water-tight fit water-tight fit

Electronics 2020, 9, 992 9 of 20

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(a) Design features

(b) Design characteristics of the head straps

Figure 1. Cont.

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(d) Design characteristics of the nose-bridges

Figure 1. Comparative results on 26 existing swimming goggles. Figure 1. Electronics 2020, 9, 992 Comparative results on 26 existing swimming goggles. 11 of 20

To understand the range of dimensions of existing swimming goggles, we purchased ﬁve To understand the range of dimensions of existing swimming goggles, we purchased five swimming goggles among the 26 swimming goggles reviewed. The dimensions (length, width, swimming goggles among the 26 swimming goggles reviewed. The dimensions (length, width, and and depth) for each component (nose bridge, frame, and gasket) were measured by a caliper in each of depth) for each component (nose bridge, frame, and gasket) were measured by a caliper in each of the axes of the XYZ coordinate systems as shown in Figure2. The measurements are summarized the axes of the XYZ coordinate systems as shown in Figure 2. The measurements are summarized in in Table2. The vertical average width of the lens measured from top to bottom in y-direction was Table 2. The vertical average width of the lens measured from top to bottom in y-direction was 31.6 31.6 mm (standard deviation (SD) = 4.4). The horizontal average length measured from left to right of mm (standard deviation (SD) = 4.4). The horizontal average length measured from left to right of the the lens in x-direction was 50.3 mm (SD = 7.9). Similarly, to the dimension of frame, the average width lens in x-direction was 50.3 mm (SD = 7.9). Similarly, to the dimension of frame, the average width was 143.2 mm (SD = 11.2), and the average length of the frame was 40.1 mm (SD = 2.7). The nose was 143.2 mm (SD = 11.2), and the average length of the frame was 40.1 mm (SD = 2.7). The nose bridge was measured for its length and width as shown in Figure2. The average of the nose bridge bridge was measured for its length and width as shown in Figure 2. The average of the nose bridge was 26.5 mm (SD = 3.6) for length, and 7.9 mm (SD = 2.5) for width. The gasket was measured for its was 26.5 mm (SD = 3.6) for length, and 7.9 mm (SD = 2.5) for width. The gasket was measured for its depth and its average was found as 10.0 mm (SD = 3.6). These dimensional information (Table2) was depth and its average was found as 10.0 mm (SD = 3.6). These dimensional information (Table 2) was used to design new swimming goggles in a CAD software. used to design new swimming goggles in a CAD software.

FigureFigure 2. 2. DimensionsDimensions of of lens, lens, nose nose-bridge,-bridge, and and gasket gasket of of swimming swimming goggles goggles [9]. [9].

Table 2. Dimensional measurements of the existing swimming goggles (W: width; L: length; D: depth; Table 2. Dimensional measurements of the existing swimming goggles (W: width; L: length; D: depth; unit in mm). unit in mm). Lens Nose Bridge Frame Gasket ExistingExisting Swimming Swimming Lens Nose Bridge Frame Gasket GogglesGoggles ( (ModelModel Names) WLWLWLD W L W L W L D NamesModel) #1 27.0 40.1 26.0 7.9 135.6 38.7 5.8 ModelModel #1 #227.0 35.840.1 56.8 26.0 25.0 7.9 7.0 135.6 147.2 43.038.7 13.85.8 Model #3 36.4 57.5 28.0 6.8 137.7 43.0 13.8 Model #2 35.8 56.8 25.0 7.0 147.2 43.0 13.8 Model #4 27.5 53.1 31.6 12.2 161.0 37.2 9.0 ModelModel #3 #536.4 31.457.5 43.8 28.0 22.0 6.8 5.7 137.7 134.3 38.643.0 7.813.8 Model #4 27.5 53.1 31.6 12.2 161.0 37.2 9.0 Mean 31.6 50.3 26.5 7.9 143.2 40.1 10.0 ModelStandard #5deviation 31.4 4.443.8 7.922.0 3.6 5.7 2.5 134.3 11.2 2.738.6 3.67.8 Mean 31.6 50.3 26.5 7.9 143.2 40.1 10.0 Standard deviation 4.4 7.9 3.6 2.5 11.2 2.7 3.6

Shau [36] patented a light reflector for the user to see any obstacles, such as the edge of the swimming pool, during a backstroke without having to turn the head from its normal position. The light reflecting function is offered by backstroke viewing windows at the top side of each eye socket. The backstroke viewing window stands vertically while the user faces the water surface. The windows can be disposed of and switched into a regular forward viewing window. The design of this patent comprises two eye sockets connected by a single head strap. The eye sockets are mounted to the suction socket which is made of rubber and has water leakage. Both eye sockets are connected by a single head strap and inserted by viewing windows which are made of transparent plastic. Chiang, in his invention [37], aimed to improve the structure of swimming goggles, especially the nose bridge. The inventor enhances the comfort of wearing the swimming goggles by attaching a soft protective pad onto the nose bridge. The soft pad could be made of a rubber sponge, plastic, or thermoplastic rubber. The soft pad under a nose bridge behaves as support and it can be a single piece or fastened to the frame. The design comprises two frames, two lenses, a nose bridge combined with a soft protective pad and joined to frames, and a double head strap. The soft protective pad is assembled with a connecting unit or nose bridge by accommodating a groove. Van invented a patented design to reduce hydrodynamic drag and optical distortion in swimming goggles by eliminating the connection unit and head strap [38]. The inventor attempts to

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Shau [36] patented a light reflector for the user to see any obstacles, such as the edge of the swimming pool, during a backstroke without having to turn the head from its normal position. The light reflecting function is offered by backstroke viewing windows at the top side of each eye socket. The backstroke viewing window stands vertically while the user faces the water surface. The windows can be disposed of and switched into a regular forward viewing window. The design of this patent comprises two eye sockets connected by a single head strap. The eye sockets are mounted to the suction socket which is made of rubber and has water leakage. Both eye sockets are connected by a single head strap and inserted by viewing windows which are made of transparent plastic. Chiang, in his invention [37], aimed to improve the structure of swimming goggles, especially the nose bridge. The inventor enhances the comfort of wearing the swimming goggles by attaching a soft protective pad onto the nose bridge. The soft pad could be made of a rubber sponge, plastic, or thermoplastic rubber. The soft pad under a nose bridge behaves as support and it can be a single piece or fastened to the frame. The design comprises two frames, two lenses, a nose bridge combined with a soft protective pad and joined to frames, and a double head strap. The soft protective pad is assembled with a connecting unit or nose bridge by accommodating a groove. Van invented a patented design to reduce hydrodynamic drag and optical distortion in swimming goggles by eliminating the connection unit and head strap [38]. The inventor attempts to keep the lens flat to prevent distortion that might occur due to water pressure, even though this can cause an increase in hydrodynamic drag. The purpose of decreasing drag force is to maintain the swimmers’ speed without having the drag force against the lens. For further improvement, the inventor minimizes the anterior-posterior depth of the eyepiece’s profile which allows water to flow over easily. Minimizing the profile depth means moving the eyepieces closer to the user’s eyes, which typically enhances the user’s vision under water. The patent design specifies that the eyepieces must have depth less than or equal to 8 mm. The design comprises a transparent material with a peripheral frame for each eyepiece. Each frame has a posterior surface for attaching the eyepiece onto the user’s skin. The design has no nose bridge or head strap, but relies on the adhesive surface or tape. Apex compared the weight of goggles that are made of two different materials, polycarbonate (PC) and polyamine-66 (PA-66) [39]. Apex reported that light weight swimming goggles are important especially among competitive swimmers. For example, Apex mentioned that the swimming goggles, New Carbon RaceTM, was made of PA-66, instead of PC, and the goggles showed 12–15% less weight compared to other common swimming goggles that were made of polycarbonate. When goggles are worn, there develops a pressure inside the goggle based on the surface area. Morgan et al. [3] developed a method to measure the amount of pressure that forms around the eye, known as intraocular pressure. This pressure can cause biological damage if it gets too high. The article forms a predictive model that determines an expected IOP on the wearer’s face. IOP is a significant contributor to glaucoma and people who are at risk of glaucoma are advised to avoid smaller eye goggles, which, in the article’s findings, exhibited the highest change in IOP among all the goggles. Considering the amount of pressure any new design will create, it was important to make sure that the goggles we designed also did not cause injury. Between the suction and pressure, there are a list of adverse side effects. Diplopia, or double vision, is one said side effect. A human’s eye movement is controlled by six muscles; four rectus muscles that allow the eyes to move up and down, as well as side to side, two oblique muscles which give added support to the rectus muscles, and the superior oblique which “ties” to a tendon called the trochlea located near the nose. This pulley-like tendon serves to aid the attached muscle in stability of the eye’s movement. Improperly fitted swimming goggles can put undue pressure on this tendon, causing the user to experience severe double vision and pain [40]. The padding serves to seal the eyes from the environment of the pool, however seals are known to fail over time and can sometimes lead to high pressures on the eyes, making the wearer uncomfortable. The proposed design seeks to eliminate the need for a padding between the eye and goggles by designing the swimming goggles with the wearer’s facial contours. Electronics 2020, 9, 992 12 of 20

3. Design Protocols of Customized Swimming Goggles This section introduces the design protocols of customized swimming goggles based on the detailed review of recently published papers [7–9]. The papers were based on the authors’ previous bodies of work conducted from 2017 through 2019. The customization protocols of swimming goggles in the published papers consist of the following five steps (see Figure3): first, ergonomic issues and limitations of the existing swimming goggles were identified. Second, design concepts were generated by brainstorming or benchmarking to resolve the identified ergonomic issues of the existing swimming goggles. Third, watertight swimming goggles were designed based on the wearer’s 3D facial scan data to incorporate the generated ideas. Fourth, a working prototype was fabricated using a 3D printer. Finally, fifth, the fabricated swimming goggles were validated in terms of ergonomic performance compared to other swimming goggles. The following paragraphs provides more details and insights for each of the design steps. Electronics 2020, 9, 992 13 of 20

Figure 3. The five-step design protocol of customized swimming goggles. Figure 3. The ﬁve-step design protocol of customized swimming goggles.

InIn the the first first step, step, the the ergonomic ergonomic problems problems or or design design issues issues of of the the existing existing swimming swimming goggles goggles were were identified.identified. Coleman Coleman et et al. al. conducted conducted benchmarking benchmarking as as well well as as a a questionnaire questionnaire-based-based survey survey with with professionalprofessional swimmers swimmers in in the the local local area area to collect feedback on the existing swimming goggles goggles worn worn andand issues issues encountered encountered [7 [7].]. Park Park et al. et conductedal. conducted a literature a literature review review to understand to understand the current the research current researchstatus of status swimming of swimming goggles, relevant goggles, patents, relevant and patents, the materials and the and materials design and features design of fea swimmingtures of swimminggoggles [8, 9goggles]. The group [8,9]. reportedThe group six reported ergonomic six issuesergonomic of the issues existing of swimmingthe existing goggles: swimming (1) impropergoggles: (1)fit, improper (2) high pressure fit, (2) high on eyes, pressure (3) leaking on eyes, water, (3) leaking (4) reduced water, visibility (4) reduced due tovisibility fog, (5) due poor to customization fog, (5) poor customizationand adjustability and of adjustability the strap, and of (6)the uncomfortablestrap, and (6) uncomfortable to wear. to wear. InIn the the second second step, step, design design ideas ideas were were generated by by brainstorming or or benchmarking benchmarking based based on on thethe existing existing products. products. The The design design requirements requirements included included fitting fitting the the goggles goggles to to the the dimensions dimensions of of a a wearer’s facial facial scan, scan, not not havin havingg any any leaks leaks in in the the frame, frame, as as well well as as having having a a drag drag coefficient coefficient lower lower than than oror comparable to to the existing swimming goggles. In In addition, addition, the the design design included included a a flexible flexible nose nose bridgebridge for for better better adjustability and fit fit as shown in Figure 44.. In the third step, customized swimming goggles were designed in a CAD environment based on the measured 3D facial scan data and the generated design concepts. When capturing a wearer’s 3D facial scan, Coleman et al. [7] used a hand-held 3D scanner (Sense 3D scanner, 3D SYSTEMS INC., Rock Hill, SC, USA; see Figure5a). The 3D hand-held scanner allows e fficient measurement of high-resolution 3D facial scan data. The measurement time was less than 10 s, the resolution of the 3D facial scan file was 69K vertices, and the type of the scan file was in Polygon file (PLY) format. However, the cost of the 3D hand-held scanner varies and the price is relatively high compared to a

Figure 4. The generated ideas for the customized swimming goggles based on the brainstorming [9].

In the third step, customized swimming goggles were designed in a CAD environment based on the measured 3D facial scan data and the generated design concepts. When capturing a wearer’s 3D facial scan, Coleman et al. [7] used a hand-held 3D scanner (Sense 3D scanner, 3D SYSTEMS INC., Rock Hill, SC, USA; see Figure 5a). The 3D hand-held scanner allows efficient measurement of high- resolution 3D facial scan data. The measurement time was less than 10 s, the resolution of the 3D facial scan file was 69K vertices, and the type of the scan file was in Polygon file (PLY) format. However, the cost of the 3D hand-held scanner varies and the price is relatively high compared to a 2D camera (the range of 3D hand held scanner price can range from $500 to $20,000 USD depending on its measurement quality), and the 3D scanner is not easily accessible to the general public, nor it is portable. For these reasons, Park et al. [8] used a typical mobile camera to measure a wearer’s 3D facial data (Figure 5b). Park et al. used a GoPro 2D camera, which can capture several 2D selfie images

Electronics 2020, 9, 992 13 of 20

Figure 3. The five-step design protocol of customized swimming goggles.

ElectronicsIn the2020 first, 9, 992step, the ergonomic problems or design issues of the existing swimming goggles13 were of 20 identified. Coleman et al. conducted benchmarking as well as a questionnaire-based survey with professional swimmers in the local area to collect feedback on the existing swimming goggles worn and2D camera issues (the encountered range of 3D [7]. hand Park held et al. scanner conducted price acan literature range from review $500 to to understand $20,000 USD the depending current researchon its measurement status of swimming quality), and goggles, the 3D relevant scanner patents, is not easily and accessiblethe materials to the and general design public, features nor of it swimmingis portable.Electronics 2020 goggles For, 9, these992 [8,9]. reasons, The group Park reported et al. [8] usedsix ergonomic a typical mobileissues of camera the existing to measure swimming a14 wearer’s of 20goggles: 3D (1)facial improper data (Figure fit, (2)5 b).high Park pressure et al. used on eyes, a GoPro (3) leaking 2D camera, water, which (4) reduced can capture visibility several due 2D to selﬁefog, (5) images poor at different angles, and then reconstruct a 3D facial features with the 2D images using a 3D image customizationat diﬀerent angles, and adjustability and then reconstruct of the strap, a 3D and facial (6) uncomfortable features with theto wear. 2D images using a 3D image reconstructionreconstruction software software (Agisoft(Agisoft Photoscan, Photoscan, Agisoft Agisoft LLC, LLC, St. Petersburg, St. Petersburg, Russia) Russia) by aligning by aligning the 2D the 2D imagesIn the appropriately. second step, Note design that ideasbefore wereconducting generated any human by brainstorming subject research or including benchmarking surveying based on images appropriately. Note that before conducting any human subject research including surveying theand existing measuring products. facial scan,The andesign experimental requirements protocol included must be approved fitting the by gogglesInstitutional to the Review dimensions Board of a and measuring facial scan, an experimental protocol must be approved by Institutional Review Board wearer’s(IRB). Thefacial work scan, conducted not havin byg Parkany leakset al. in[8] the was frame, approved as well by theas havingIRB at Texas a drag A&M coefficient University lower- than or(IRB). comparableCorpus The Christi work to conductedprior the toexisting the bystart Park swimming of the et al.work [8 ] goggles.(IRB was approvedID: NHS In addition, 19 by-19). the IRBthe atdesign Texas included A&M University-Corpus a flexible nose bridgeChristi forThe prior better requirements to the adjustability start for of the anddesigned work fit (IRBas swimming shown ID: NHS in gogglesFigure 19-19). are4. listed as follows: the design must use the 3D facial scan data. In addition, the goggles must prevent water leakage when the swimmer is wearing them. The material used to create the swimming goggles must be comfortable to the user and must have a stable construction (if the swimming goggles are not stable there can be water leakage, or the goggles may crack from the pressure of the water). The goggles’ lenses must be clear and visible for the wear while maintaining safety standards. The overall design must improve the quality of the swimming goggles for the wearer. The design specifications for the swimming goggles were constructed with the help of the following computer software programs: AutoCAD (Autodesk, Inc., San Rafael, CA, USA), Inventor 2016 (Autodesk, Inc., USA), and 3Ds Max (Autodesk, Inc., USA). Using the 3D facial scan data, the goggles were made to fit uniquely to the face of the scanned individual. The swimming goggle dimensions depended on the 3D facial scan data. The depth, height, and length also depended on the person’s facial features. The material used to construct the custom swimming goggle design was VeroClearFigureFigure 4. 4. [ 41TheThe], andgenerat generated bungeeed ideas ideas material for for the thewas customized customized used for the swimming swimming strap. goggles goggles based based on on the the brainstorming brainstorming [9] [9]..

In the third step, customized swimming goggles were designed in a CAD environment based on the measured 3D facial scan data and the generated design concepts. When capturing a wearer’s 3D facial scan, Coleman et al. [7] used a hand-held 3D scanner (Sense 3D scanner, 3D SYSTEMS INC., Rock Hill, SC, USA; see Figure 5a). The 3D hand-held scanner allows efficient measurement of high- resolution 3D facial scan data. The measurement time was less than 10 s, the resolution of the 3D facial scan file was 69K vertices, and the type of the scan file was in Polygon file (PLY) format. However, the cost of the 3D hand-held scanner varies and the price is relatively high compared to a 2D camera (the range of 3D hand held scanner price can range from $500 to $20,000 USD depending on its measurement quality), and the 3D scanner is not easily accessible to the general public, nor it is portable. For these reasons, Park et al. [8] used a typical mobile camera to measure. a wearer’s 3D facial data (Figure 5b). Park et al. used a GoPro 2D camera, which can capture several 2D selfie images (a) Capturing 3D facial scan using a hand-held 3D scanner [7]

(b) Reconstructing a 3D facial image based on multiple 2D images captured by GoPro [8]

FigureFigure 5.5. Measurement and and reconstruction reconstruction of a ofwearer’s a wearer’s 3D facial 3D facialimages images..

Electronics 2020, 9, 992 14 of 20

The requirements for the designed swimming goggles are listed as follows: the design must use the 3D facial scan data. In addition, the goggles must prevent water leakage when the swimmer is wearing them. The material used to create the swimming goggles must be comfortable to the user and must have a stable construction (if the swimming goggles are not stable there can be water leakage, or the goggles may crack from the pressure of the water). The goggles’ lenses must be clear and visible for the wear while maintaining safety standards. The overall design must improve the quality of the swimming goggles for the wearer. The design specifications for the swimming goggles were constructed with the help of the following computer software programs: AutoCAD (Autodesk, Inc., San Rafael, CA, USA), Inventor 2016 (Autodesk, Inc., San Rafael, CA, USA), and 3Ds Max (Autodesk, Inc., San Rafael, CA, USA). Using the 3D facial scan data, the goggles were made to fit uniquely to the face of the scanned individual. The swimming goggle dimensions depended on the 3D facial scan data. The depth, height, and length also depended on the person’s facial features. The material used to construct the custom swimming goggle design was VeroClear [41], and bungee material was used for the strap. In this step, the inner shape of the swimming goggles was designed to match the contact surface of the wearer’s facial scan, so that the inner shape of swimming goggles would fit perfectly to the wearer’s skin. By considering the wearing positions of existing swimming goggles, the 3D shape of the wearer’s eye region scan data was used to design the inner shape of customized goggles. Coleman et al. [7] used the 3D shape of the wearer’s nasal root area to design the shape of nose bridge using Autodesk Inventor Professional 2016 (Autodesk Inc., San Rafael, CA, USA) and created the 3D model of the customized swimming goggles (see Figure6a). The final design had a seal between the wearer’s face and swimming goggles and leakage prevention was determined by the contact between the goggles and the wearer, and how well the contours of the swimming goggle matched the contours of the wearer’s face. The custom swimming goggles were curved to increase the swimmer’s visibility when swimming. In addition, the dimensions of the swimming goggles were determined based on brainstorming for design ideas as well as benchmarking results from existing swimming goggles (Table2). The generated design by Park et al. [ 9] included 0.25 mm fillet radius that helps to reduce the drag force by spreading the distribution of pressure. The geometry included curve and edges. The design had a maximum diameter of 2.2 mm for the nose bridge holder and 5.4 mm for the head strap coupler. The thickness of the design was 2.0 mm for the eyecup and 1.6 mm for the coupler. The lowest depth was 7.6 mm while the tallest depth was 20.8 mm. The width of this design was 37.9 mm. The shape of the lens was also designed to minimize the drag force while swimming (see the hydrodynamic simulation results in Figure6b). The program, Flow Design (Autodesk, Inc., San Rafael, CA, USA) was used to determine the drag force and drag coefficient of water acting on the design by simulating water flowing across the design at various angles. By taking the average speed of a swimmer, the simulation shows the drag force and drag coefficient in real time. The angle at which the goggles are fixed on the user’s face effects how large or small the drag force and coefficient is. By using this data, the authors can find the ideal angle the goggles should rest on the wearer’s face in order to reduce the potential drag force and coefficient. The program determined drag coefficient and drag forces acting on the goggles while swimming at 2.2 m/s. As shown in Figure6 the ideal angle the goggles should be at is 20 degrees, because at 20 degrees the goggles provide the least amount of drag force and drag coefficient. This simulation provides insight on how much drag force will be applied while swimming, and the optimal angle to produce the least amount of drag force, reducing the likelihood of the goggles to fall off. Electronics 2020, 9, 992 15 of 20

In this step, the inner shape of the swimming goggles was designed to match the contact surface of the wearer’s facial scan, so that the inner shape of swimming goggles would fit perfectly to the wearer’s skin. By considering the wearing positions of existing swimming goggles, the 3D shape of the wearer’s eye region scan data was used to design the inner shape of customized goggles. Coleman et al. [7] used the 3D shape of the wearer’s nasal root area to design the shape of nose bridge using Autodesk Inventor Professional 2016 (Autodesk Inc., San Rafael, CA, USA) and created the 3D model of the customized swimming goggles (see Figure 6a). The final design had a seal between the wearer’s face and swimming goggles and leakage prevention was determined by the contact between the goggles and the wearer, and how well the contours of the swimming goggle matched the contours of the wearer’s face. The custom swimming goggles were curved to increase the swimmer’s visibility when swimming. In addition, the dimensions of the swimming goggles were determined based on brainstorming for design ideas as well as benchmarking results from existing swimming goggles (Table 2). The generated design by Park et al. [9] included 0.25 mm fillet radius that helps to reduce the drag force by spreading the distribution of pressure. The geometry included curve and edges. The design had a maximum diameter of 2.2 mm for the nose bridge holder and 5.4 mm for the head strap coupler. The thickness of the design was 2.0 mm for the eyecup and 1.6 mm for the coupler. The lowest depth was 7.6 mm while the tallest depth was 20.8 mm. The width of this design was 37.9 mm. The shape of the lens was also designed to minimize the drag force while swimming (see the hydrodynamic simulation results in Figure 6b). The program, Flow Design (Autodesk, Inc., San Rafael, CA, USA) was used to determine the drag force and drag coefficient of water acting on the design by simulating water flowing across the design at various angles. By taking the average speed of a swimmer, the simulation shows the drag force and drag coefficient in real time. The angle at which the goggles are fixed on the user’s face effects how large or small the drag force and coefficient is. By using this data, the authors can find the ideal angle the goggles should rest on the wearer’s face in order to reduce the potential drag force and coefficient. The program determined drag coefficient and drag forces acting on the goggles while swimming at 2.2 m/s. As shown in Figure 6 the ideal angle the goggles should be at is 20 degrees, because at 20 degrees the goggles provide the least amount of drag force and drag coefficient. This simulation providesElectronics insight2020, 9, on 992 how much drag force will be applied while swimming, and the optimal angle15 to of 20 produce the least amount of drag force, reducing the likelihood of the goggles to fall off.

Electronics(a) Design 2020, 9 of, 992 a 3D model of the customized swimming goggles with the wearer’s 3D facial scan [7].16 of 20

(b) Hydrodynamic simulations to minimize drag forces [7].

FigureFigure 6. 6.Design Design and and evaluation evaluation of of the the 3D 3D model model of of customized customized swimming swimming goggles. goggles.

InIn the the fourth fourth step, step, the the designed designed customized customized swimming swimming goggles goggles were were fabricated fabricated by by using using a a 3D 3D printer.printer. In In this this prototyping prototyping stage, stage, either either hard hard or or soft soft materials materials can can be be used used to to create create the the prototype. prototype. ColemanColeman et et al.al. [[7]7] usedused a hard hard material material for for fabricating fabricating the the swimming swimming goggles goggles (see (see Figure Figure 7a).7a). The Theprototype prototype was was all one all onepiece piece printed printed entirely entirely from from polycarbonate polycarbonate material. material. On the On other the hand, other hand,Park et Parkal. [8] et al.used [8] softused material soft material (see Figure (see Figure 7b). Ninja7b). Ninja Flex and Flex polycarbonate and polycarbonate materials materials were wereused usedfor the forgoggle the goggle gasket gasket and lenses, and lenses, respectively. respectively. For the For 3D the printing, 3D printing, Park et Park al. [8] et al.used [8] LULZBOT used LULZBOT TAZ 6 TAZ(Aleph 6 (Aleph Objects, Objects, Inc., Inc.,USA), USA), which which enables enables printing printing with with various various materials materials including including nylon nylon and andpolycarbonate polycarbonate..

(a) One-peace prototype [7] (b) Two-peace prototype [8]

Figure 7. The fabricated working prototypes of the customized swimming goggles.

In the fifth step, the fabricated swimming goggles were evaluated by comparing with other swimming goggles. Coleman et al. [7] conducted a swimming pool test to compare the developed and existing swimming goggles in wearing comfort, leakage, visibility, in-water maneuvers, and fit with standing dive into water (see Figure 8). The subjective evaluations were completed using the 5- point Likert scale (1 = not satisfied, 5 = very satisfied). In addition, the water leakage was evaluated in the swimming pool by measuring the amount of leaked water. Even though the testing was done by one participant, it is an exploratory result, helping the authors focus on improvements in the next iteration of this protocol.

Electronics 2020, 9, 992 16 of 20

(b) Hydrodynamic simulations to minimize drag forces [7].

Figure 6. Design and evaluation of the 3D model of customized swimming goggles.

In the fourth step, the designed customized swimming goggles were fabricated by using a 3D printer. In this prototyping stage, either hard or soft materials can be used to create the prototype. Coleman et al. [7] used a hard material for fabricating the swimming goggles (see Figure 7a). The prototype was all one piece printed entirely from polycarbonate material. On the other hand, Park et al. [8] used soft material (see Figure 7b). Ninja Flex and polycarbonate materials were used for the goggle gasket and lenses, respectively. For the 3D printing, Park et al. [8] used LULZBOT TAZ 6 (AlephElectronics Objects,2020, 9, 992 Inc., USA), which enables printing with various materials including nylon16 and of 20 polycarbonate.

(a) One-peace prototype [7] (b) Two-peace prototype [8]

FigureFigure 7. 7. TheThe fabricated fabricated working working prototypes prototypes of of the the customized customized swimming swimming goggles. goggles.

InIn the the fifth fifth step, step, the the fabricated fabricated swimming swimming goggles goggles were were evaluated evaluated by by comparing comparing with with other other swimmingswimming goggles. goggles. Coleman Coleman et et al. [[7]7] conductedconducted aa swimming swimming pool pool test test to to compare compare the the developed developed and andexisting existing swimming swimming goggles goggles in wearing in wearing comfort, comfort, leakage, leakage, visibility, visibility, in-water in-water maneuvers, maneuvers, and and fit with fit withstanding standing dive dive into into water water (see (see Figure Figure8). The 8). subjectiveThe subjective evaluations evaluations were were completed completed using usin theg 5-point the 5- pointLikert Likert scale scale (1 = not(1 = satisfied,not satisfied, 5 = very 5 = very satisfied). satisfied). In addition, In addition, the water the water leakage leakage was evaluatedwas evaluated in the inswimming the swimming pool bypool measuring by measuring the amount the amount of leaked of leaked water. water. Even thoughEven though the testing the testing was done was bydone one byparticipant, one participant it is an, it exploratory is an exploratory result, result helping, helping the authors the authors focus on focus improvements on improvements in the next in the iteration next iterationof this protocol. of this protocol. Electronics 2020, 9, 992 17 of 20

FigureFigure 8. 8.Evaluation Evaluation of of the the customized customized swimming swimming goggles goggles compared compared to the existing to the existing swimming swimming goggles. Thegoggles. bar chart The shows bar chart total subjectiveshows total ratings subjective of each ratings of the goggles of each across of the all goggles subjective across evaluation all subjective criteria. evaluation criteria. 4. Discussion 4. Discussion In the present study, an extensive review was conducted on existing swimming goggles in terms of design,In the materials, present study, and dimensions. an extensive The review identiﬁed was conducted design features on existing of the swimming existing swimming goggles in goggles terms willof design, be useful materials, when designing and dimensions. customized The swimming identified goggles design and features optimizing of theparameters existing for swimming usability andgoggles minimal will eyebe useful pressure. when designing customized swimming goggles and optimizing parameters for usabilityThe price and of minimal commercial eye pressure. swimming goggles varies based on the design, physical properties, and theTheability price of of commercial the goggles swimming to provide goggles comfort. varies The based price rangeon the is design, typically physical from properties, USD $3 to $75.and However,the ability there of the is only goggles one company to provide which com providesfort. The customized price range 3D is printed typically swimming from USD goggles $3 to based $75. onHowever, a wearer’s there facial is only data, one TheMagic5 company™ whichInc. (North provides Carolina, customized USA) [ 3D42] printedis accessible swimming online thoughgoggles abased phone on application a wearer’s for facial both data, Android TheMagic5™ and iOS systems.Inc. (North TheMagic5 Carolina, produces USA) [42 individual] is accessible swimming online gogglesthough using a phone 2D facialapplication scan. The for lowestboth Android price oﬀ andered iOS by TheMagic5 systems. TheMagic5 is $54. produces individual swimming goggles using 2D facial scan. The lowest price offered by TheMagic5 is $54. The customized design protocol was intended to improve the user’s comfort during swimming and reduce drag. Coleman et al. [7] measured a wearer’s 3D facial data using a 3D scanner. However, in general, 3D scanners are not easily accessible because of the high cost and additional software installation required on a computer to visualize the captured 3D facial features. The main outcome of the work by Park et al. [8] was a protocol for designing custom-made swimming goggles using multiple self-captured photos from any off-the-shelf camera or a camera on a smart device to create 3D facial scan data. A typical 2D camera used by Park et al. is more easily accessible than a 3D scanner; therefore, the data collection process has been made more user-accessible and easier than what was presented in the Coleman et al. Even with the reduced cost of 2D facial scan data collection, data analysis and 3D facial data reconstruction still requires a licensed software tool (Photoscan), and is not free; therefore, as part of the future work, the team plans to develop a free mobile application that can construct 3D facial data from a number of 2D selfie images. The simulation results in Coleman et al. showed that 20 degrees with respect to horizontal can provide reduced drag force and drag coefficient compared to other angles (0° and 10°; see Figure 5). The simulations provide an insight into how much drag force will be applied while swimming; the angle with the least amount of drag force will make the goggles less likely to fall off and more efficient during swimming. Although the one-piece style prototype created in Coleman et al. was functional, it did not have seals potentially creating user discomfort over long-term use in the water despite perfectly fitting to the contours of the user’s face. Another major shortfall was the less-than-optimal comfort experienced by the user in the nose area, because the nose bridge of the goggles was rigid. The final major challenge of the one-piece design involved the polycarbonate being printed on a surface that was not ideal for printing clear material. Since the entire design was one solid piece printed entirely of polycarbonate, it was not very cost-effective, as polycarbonate is more expensive than most other printing filaments. To address these issues, the design in Park et al. [8] was improved by converting the goggles into a two-piece design, where the lenses and frame form separate parts with different materials. The protocol required a seal to be created, followed by a nose bridge that was made of a

Electronics 2020, 9, 992 17 of 20

The customized design protocol was intended to improve the user’s comfort during swimming and reduce drag. Coleman et al. [7] measured a wearer’s 3D facial data using a 3D scanner. However, in general, 3D scanners are not easily accessible because of the high cost and additional software installation required on a computer to visualize the captured 3D facial features. The main outcome of the work by Park et al. [8] was a protocol for designing custom-made swimming goggles using multiple self-captured photos from any off-the-shelf camera or a camera on a smart device to create 3D facial scan data. A typical 2D camera used by Park et al. is more easily accessible than a 3D scanner; therefore, the data collection process has been made more user-accessible and easier than what was presented in the Coleman et al. Even with the reduced cost of 2D facial scan data collection, data analysis and 3D facial data reconstruction still requires a licensed software tool (Photoscan), and is not free; therefore, as part of the future work, the team plans to develop a free mobile application that can construct 3D facial data from a number of 2D selfie images. The simulation results in Coleman et al. showed that 20 degrees with respect to horizontal can provide reduced drag force and drag coefficient compared to other angles (0◦ and 10◦; see Figure5). The simulations provide an insight into how much drag force will be applied while swimming; the angle with the least amount of drag force will make the goggles less likely to fall off and more efficient during swimming. Although the one-piece style prototype created in Coleman et al. was functional, it did not have seals potentially creating user discomfort over long-term use in the water despite perfectly fitting to the contours of the user’s face. Another major shortfall was the less-than-optimal comfort experienced by the user in the nose area, because the nose bridge of the goggles was rigid. The final major challenge of the one-piece design involved the polycarbonate being printed on a surface that was not ideal for printing clear material. Since the entire design was one solid piece printed entirely of polycarbonate, it was not very cost-effective, as polycarbonate is more expensive than most other printing filaments. To address these issues, the design in Park et al. [8] was improved by converting the goggles into a two-piece design, where the lenses and frame form separate parts with different materials. The protocol required a seal to be created, followed by a nose bridge that was made of a more flexible material to allow the goggles to have some flexibility to decrease applicable stress and increase user comfort. The prototyping protocol created for the soft material has two improvements compared to the hard material protocol: first, in the case of the hard material, it is difficult to secure the wearer’s comfort at the points of contact because of limited flexibility of the hard material. By using the soft material, it is possible to increase the wearer’s comfort in the area of contact with the goggles because of better flexibility of the soft material. Second, hard material does not accommodate skin movements and deformations around eyes, whereas the soft material has the advantage of being able to accommodate skin movements around the eyes more effectively. We conducted the experiment with one participant. The participant chosen was an accomplished swimmer who would be available over the three years of iterations of this study and who would be able to provide feedback on the improvements of the goggles. The opinion of this competitive swimmer was used as a standard for comparing multiple goggles. It should be noted here that there are two main reasons for recruiting one participant, one of which included budget constraints for the pilot studies to develop a working prototype. Generally, prototyping one unique goggle costs around 300–500 USD in materials, and around 900 h in labor (5 individuals 5 h per week 9 months). × × The second main reason was based on the developers’ project timeline that required each iteration of the prototype including development and testing to be completed within one year. With more budget and time, the number of participants could be increased for statistical analyses. However, we believe that by keeping the tester the same, we were able to validate the functionality of the developed prototype through improvements over three-year iterations. The present study advances the scientific merit in designing swimming goggles by incorporating the virtual design and validation protocols. First, to the best of our knowledge, this study is the first research that uses an individual’s 3D facial anthropometric data to design swimming goggles by matching the 3D shape of nasal bridge and eye regions with the inner shape of the custom-made Electronics 2020, 9, 992 18 of 20 swimming goggles. Second, the presented hydrodynamic simulations for the swimming goggles have never been published elsewhere. The proposed validation protocol combines software simulations as well as physical tests to find an optimal design as well as quantitatively evaluate the hydrodynamics of the swimming goggles. In addition, this simulation protocol is a safe way to validate goggles compared to a typical human subject experiment. Apparently, it would be impractical to ask any participant to test goggles’ hydrodynamics in the water. In conclusion, by effectively designing goggles using the individual’s 3D anthropometric data and using the simulation tool, the authors qualitatively and quantitatively validated the goggles. The presented work could be used as a reference for further studies to develop any kinds of custom-made goggles, not just swimming goggles, that include other types of eye wear and devices.

5. Conclusions The developed design protocol can be applied to improve the ﬁt of other types of wearable products, such as hats, snorkeling gear, suits, and industrial safety goggles. By applying the proposed protocol, custom designed swimming goggles that match the contours of an individual’s face can be created by mass-customization production protocol, which is expected to reduce the production cost for customized goggles. The identiﬁed features from existing goggles provide an insight of preferred features that can be exploited in new ergonomic designs for facial wearable products.

Author Contributions: Conceptualization, data collection and analysis, and validation J.P. (Jangwoon Park); writing-original draft preparation, J.P. (Jangwoon Park) and M.M.; writing-review and editing, J.K., and J.P. (Jaehyun Park). All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by Incheon National University (International Cooperative) Research Grant in 2020 (Grant No.: 20200172). Conﬂicts of Interest: The authors declare no conﬂict of interest.

References

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