Spectrum of Applications New Trends in Microfabrication

Highest Resolution 3D Printing Overview

Additive Manufacturing & Maskless Lithography

The 3D laser lithography system, Subsequent independent processes In this issue Page Photonic Professional GT, sets new enable the transfer and/or replication standards in 3D microprinting and of polymeric 3D printed templates into Additive Manufacturing & 2 maskless lithography. This highest a large choice of materials, including Maskless Lithography ­resolution 3D printer enables the rapid metals and semiconductors. Wide Spectrum of Applications 3 fabrication of nano-, micro- and meso- structures with feature sizes starting The additive manufacturing of 2D, Application Perspective for 4 from about hundred nanometers up 2.5D and 3D objects paves the way Maskless Lithography to several micro­meters. Surfaces typi- for a wide field of novel applica- Maskless Lithography 5 cally covered are in the range of up to a tions. This ability makes the Photonic Additive Manufacturing 5 few cm² laterally and print volumes of Professional ­ GT extremely versatile for Microfluidics up to several 10 mm³. Unlike other 3D which is particularly appreciated in Bio-Inspired Skin-Like Displays 6 printing technologies, layer thickness multi-user facilities. and thus a resulting surface roughness Casting 6 is just a question of the right set of In 2014, the outstanding perfor- Additive Manufacturing of 7 parameters – thus optical quality sur- mance of the Photonic Professional GT Micro-Optics face finishes can be reached. ­systems was underlined by the receipt Foveated Imaging 7 of the Prism Award in the category 3D Photonics 8 In combination with tailor-made pho- “Advanced Manufacturing”. In 2015 toresists, hardware- and software Nanoscribe was recognized as winner Coating and Plating Processes for 8 packages, the turn-key system is of the World Technology Award (WTN) Polymer Templates embedded best along the 3D printing for its outstanding achievements in Photonic Wire Bonds 9 workflow and allows for highest res- “materials”. Unfeelability Cloak Protects 10 olution with a previously unavailable the Princess from the Pea freedom of design. 3D Printed Micro-Trusses 11 Cells Conquer the Third 12 Dimension Bio-Inspired Osteoprints for the 13 Enhancement of the Osteogenic Differentiation Magnetic Helical Micromachines 14 Rapid Prototyping of Micro- 15 and Mesoparts

Imprint: Nanoscribe GmbH CEO: Martin Hermatschweiler Registered office of the association: 76344 Eggenstein-Leopoldshafen (DE) District court: Mannheim HRB 703637, VAT-No. DE258161584 Tax-No. 34415/77104

Editor: Martin Hermatschweiler Assistant Editor: Anke Werner Contributions: Nicole Lindenmann (Karlsruhe Institute of Technology, KIT- IPQ), Tiemo Bückmann (KIT-APH), Jens Bauer (KIT-IAM), Martin Bastmeyer (KIT-CFN), Debashis Chanda (NSTC/ CREOL, UCF), Li Zhang (ETH Zürich), Attilio Marino (IIT Pontedera), Yann Tanguy, Fabian Niesler, Andreas Frölich (Nanoscribe) Layout & Design: Katja Thieme

2 Applications

Wide Spectrum of Applications

Photonic Professional GT systems are • Micro-Optics, Diffractive Optics • Biomedical Devices being used successfully for a broad • Wafer-Level Optics • Biomimetics range of applications on the nano-, • Optical Security Labels • Micromanipulation micro- and mesoscale. • Plasmonics • Designer Mechanics The printers are drivers of innovation • Sensors • Microrobotics for numerous key technologies and • Photonic Crystals & Metamaterials • Rapid Prototyping & provide unprecedented solutions for • Microfluidics Small Series Production scientific and industrial challenges. • Life Sciences You will find a selection of application notes on our website for download. 2D 2.5D 3D

1 cm 0.5 mm 1 mm macro

15 µm mm 5 µm 1 mm meso

50 µm 100 µm 1 mm micro

1 µm 50 µm 20 µm nano

10 µm 5 µm 10 µm Courtesyof Prof. Mu Wang, University, Nanjing China

3 2D and 2.5D Fabrication

Application Perspective for Maskless Lithography Anti-counterfeit features

Counterfeiting of goods has huge economic consequences with an esti- mated global loss of $654 billion per year. This negative economic impact hits many different product categories ranging from medicine, electronics and watches to counterfeit documents like money and IDs. [1]

To fight product counterfeiting, manufactures nowadays have many anti-counterfeit technologies avail- able. A whole industry is dedicated to provide security features that enable the authentication of products and deter product imitators based on dif- ficulty or costs to replicate these fea- tures. 5 µm Fig. 2 Diffraction pattern after passing through a polymer diffractive optical element Most common features today belong directly fabricated with a Photonic Professional GT. to the class of security level 1. These overt features can be authenticated by naked eye or tactile sense therefore When illuminated with coherent light or roll-to-roll fabrication to get the being user verifiable without the need from a laser pointer, a previously hid- security labels. Nanoscribe‘s high-res- of additional tools. [2] Most prominent den image can be projected on a flat olution 2D and 2.5D patterning examples known to the public from ­surface for authentication. capabilities enable the mastering of many banknotes found around the high-resolution overt features like world are holograms, color-flipping or Fabrication of these features requires fine-line prints, diffractive color prints fine-line prints. Recent developments constructing a master using high-­ or diffractive optical elements in one incorporate transparent windows resolution lithography methods as lithography step. into polymer banknotes that con- a first step. This master is finally tain a diffractive optical element. [3] mass-replicated using stamping The examples of the photonic color image [fig. 1] and the diffractive optical element [fig. 2] projecting our company logo were fabricated using a Photonic Professional GT to demonstrate the feasibility for these applications. For further questions on this topic, please contact us via [email protected].

[1] http://www.havocscope.com/category/ counterfeit-goods/ [2] Anti-counterfeit Technologies for the Protection of Medicines http://www.who. int/impact/events/IMPACT-ACTechnolo- giesv3LIS.pdf [3] WinDOE™, http://www.polymernotes. de/files/WinDOE_Flyer_secure.pdf Fig. 1 Example of a colorful QR code consisting of diffractive dot arrays.

4 Microfluidics

Maskless Lithography 2D manufacturing by direct laser writing

While known for its outstanding 3D list of compatible negative-tone photo- printing capabilities, the Photonic Pro- resists are SU-8 as well as Nanoscribe’s fessional GT also enables high-resolu- IP-resins that provide robust and tion 2D patterning of thin films, called reliable process results. maskless lithography. Nanoscribe has recently evaluated The technology of direct laser writing the performance of the Photonic (DLW) complements 2D manufactur- Professional GT for 2D patterning ing technologies available on the mar- of various thin- and thick-film posi- ket and represents an alternative to tive tone resists of the AZ® series [2] traditional electron-beam litho­graphy (AZ® 9260, AZ® 5214E, AZ® MIR 701, Checkerboard arrangement of test patterns (EBL) and photolithography technol- AZ® 40XT) on glass and silicon sub- fabricated in positive-tone resist AZ® 5214 on 4 inch silicon wafer. ogies offering similar performance strates. These resists and substrates levels. 2D photoresist structuring cover a broad range of application using a DLW approach does not require fields, e.g. etch masks, sputter masks, expensive masks which makes it an high-aspect ratio structures and ideal tool for all aspects of prototyping electro­-plating templates. applications as well as fabrication of masters. Structures with high-aspect [1] D.S. Engstrom et al., „Additive nanoma- ratios can be achieved without lim- nufacturing – A review“, J. Mater. Res., 2014. itations from Beer’s absorption law or [2] These resists are available off the shelf electron scattering effects. Along the from www.microchemicals.com. Zoom-in on high-aspect-ratio grating fabri- cated in thick positive-tone resist AZ® 9260. Additive Manufacturing for Microfluidics Microfluidic applications benefit from highest resolution 3D printing

The precise control and manipulation available today. However, the majority applications. It transfers the bene- of liquids in very small volumes is the of these technologies are based on 2D fits of additive manufacturing to the essence of the multidisciplinary field and 2.5D manufacturing capabilities. microscale and allows the fabrication of microfluidics. Typical devices rely Recently, 3D printing technologies of complex, arbitrarily shaped 3D on components like channel systems, attract an ever increasing interest for structures in a single step. connectors and 3D mixer elements micromanufacturing of microfluidic to passively guide the flow of liquids. applications. In addition, due to its process compati- Active microfluidic components in bility with a broad range of substrates, contrast aim to actively manipulate Two-photon polymerization (2PP) is 2PP is well suited to be combined the movement of the fluids by means the 3D printing technology with the with other conventional silicon-based of micro pumps or valves. To fabricate highest resolution available today and micromanufacturing technologies these components, a broad range of is compatible with a broad range of there­by leveraging the advantages or micromanufacturing technologies is polymers well suited for microfluidic different technologies.

30 µm 20 µm 2 µm

High-aspect-ratio blocks for the imple- Microfluidic filter element structured in Close-up of a microfluidic filter element mentation of a capillary pump system. SU-8 (Design provided by IMSAS).

5 Plasmonics

Bio-Inspired Skin-Like Displays Fabrication of a 2.5D master pattern array

(Debashis Chanda) The range of col- expensive and tedious electron-beam ors and hues in the natural world (EBL) or deep-UV lithography tech- are amazing, but perhaps even more niques used in fabricating many previ- astonishing is the ability of certain spe- ously reported plasmonic devices. This cies to actively mimic them. Though in combination with ultrafast direct the specific mechanisms are as varied laser writing (DLW) using Nanoscribe’s as the species, each has a set of color laser lithography system, we can incor- producing cells which can span the porate multiple features at varying visible spectrum. The key aspect of size scales into our master patterns. color displays in nature is generation A single device master can include of color on a thin, flexible and confor- arbitrarily pixelated plasmonic sur- mally mapped surface whereas our faces, microscopic LC cell spacers, and manmade state-of-the art displays nanoscale LC alignment gratings. One still remained rigid, brittle and bulky in such master can produce 100’s of poly- nature. meric imprinting stamps, and one such stamp can produce 1000’s of imprints It’s with mimicking nature in mind that without any noticeable pattern deg- we at Nano-Optics group, University radation. NIL has also been translated D. Franklin et al., Nature Communications of Central Florida developed a flexible to roll-to-roll processing which shows 6, 7337 (2015) reflective plasmonic display in which the entire fabrication process can be each pixel is actively tuned across the scaled to factory norms. visible spectrum using liquid crystals (LC). The implementation of dynamic Now we wish to bring these results [1] Polarization-independent actively tun- pixels reduces the need for multiple from the lab to the world through able colour generation on imprinted plas- colored subpixels, thereby eliminating ‘e-skin displays Inc.’. The journey will monic surfaces Franklin, D., Chen, Y., Vaz- layered processing steps, increasing continue, as we attempt to fully realize quez-Guardado, A., Modak, S., Boroumand, resolution, and allowing unrivaled color nature-like color generation. J., Xu, D., Wu, S.-T., and Chanda, D. control. Using nanoimprint lithography Nature Communications 6,7337, (NIL) to produce the plasmonic struc- This article was provided by our cus- DOI:10.1038/ncomms8337 tures over large areas, we can bypass tomer NSTC/CREOL, UCF, Dr. D. Chanda

Casting PDMS stamps for structure replication

Nanoscribe’s Photonic Professional GT manifold times in different materials. a stamp to replicate the original printers are the ideal tool for the fab- The SEM micrographs below show an structure (right image). Imprinting is rication of high-precision masters with exemplary workflow: A master made the simplest technique that secures a replicable surface topography. Once of IP-L resist (left image) is casted into ­successful replication results for low design requirements for replication polydimethylsiloxane resist, Sylgard®­ quantity fabrication. Once it comes to are fulfilled, large-area 2.5D printed 184 Silicone Elastomer (center image). mass production at low costs, injec- polymer structures can be reproduced Next, this negative copy is used as tion molding is an ideal alternative.

IP-L Master 4 µm PDMS Negative IP-L Replica

A variety of casting techniques allow to transfer complex photoresist structures into materials such as metals, semiconductors, silica, silicon or PDMS.

6 Micro-Optics

Additive Manufacturing of Micro-Optics Superior products by overcoming design constraints

Flexibility and freedom of design are printers allow to directly fabricate well known benefits associated with polymer micro-optical components the technology of 3D printing which with significantly smaller geometrical enable faster innovation speeds in a constraints than standard fabrica- variety of applications. tion methods, high shape accuracy But up to now, the usual additive and optically smooth surfaces. Its ­manufacturing technologies avail- additive manufacturing workflow able on the market do not provide the also drastically shortens the design- 100 µm ­resolution and precision that is needed iteration phase and ideas can be turned to compete with established micro-­ into functional prototypes within just Array of semisphere micro-optics directly optics manufacturing technologies. a few days. fabricated with a Photonic Professional GT.

However, a broad range of almost arbi- Polymer master structures for indus- trary micro-optical shapes including trial mass replication, micro-optical diffractive optical elements, standard components on wafer-level as well as refractive micro-optics, multiplet lens complex compound lens systems and systems, optical interconnects and even photonic wirebonds can be fabricated freeform optics can now be printed in based on the same technology which a one step-process using Nanoscribe’s makes the Photonic Professional GT a Photonic Professional GT 3D printers. flexible tool for academia and industry 100 µm In combination with the right mate- alike enabling unprecedented applica- rials and processes, Nanoscribe’s 3D tions in micro-optics. 3D printed polymer master of primitive optical shapes

Foveated Imaging 3D printed sensor with eagle eye

Researchers from the University of Stuttgart used Nanoscribe’s ­Photonic Professional GT system to print micro-objective lenses with different focal lengths onto a high-resolution CMOS chip. All images created by the lenses on the chip are simultaneously read out electronically and processed into an image with a significantly improved resolution in the centre.

Previously, it took a large number of cameras and sensors to produce this so-called “foveated imaging”, which, in the automotive industry, for exam- ple, had to be installed all around the vehicle. Thanks to this new method it is now possible to produce cameras with sensors that mirror the extra wide field of vision of an eagle’s eye. In addition to the automotive industry, CMOS Sensor with different focal lengths for „foveated imaging“ (© University the researchers are also envisioning of Stuttgart / PI 4), References: Thiele, S., Arzenbacher, K., Gissibl, T., Giessen, H., applications for smartphones or in the Herkommer, A. M., “3D-printed eagle eye: Compound microlens system for foveated medical field. imaging”, Science Advances, 3, 2017, DOI: 10.1126/sciadv.1602655

7 Photonics

3D Photonics Semiconductors & metamaterials for light

After the invention of the laser in 1960, the concepts of photonic crystals and such nanostructured materials are optics turned into photonics. In today’s metamaterials have opened the door subject of current research activities. telecommunication tech­nology, pho- to a completely new class of materials. tons have already become the main Shown is a series of structures fabri- carrier of information. Molding the flow of light as well as cated by means of the direct laser writ- During the last decades, a number of controlling the dynamics of photons ing process achieved with Photonic pioneering developments such as, e.g., are two key issues. The properties of Professional GT systems.

1 µm

Circular spirals seen from above.

20 µm

Above: Bi-chiral photonic crystals, produced by the group of Prof. Dr. Martin Wegener (KIT). Right: 3D photonic crystalline diamond structure. With permission of Prof. Dr. Keiichi 2 µm Edagawa, University of Tokyo.

Coating and Plating Processes for Polymer Templates Turning 3D printed polymer microstructures into other materials

With two-photon polymerization 3D freedom of design and functionality. CVD [2], and electroless plating [3] microprinting almost arbitrarily shaped Electro- and electroless plating, chem- deposit material on all surfaces of an polymer nano- and microstructures can ical vapor deposition (CVD) and atomic object. Electroplating [4] is used to be made. Replicating, inverting or coat- layer deposition (ALD) are deposition grow metals into the tubes of 3D tem- ing a printed structure in/with a mate- techniques that can be used to deposit plates, starting from the conductive rial of choice, allows for nearly limitless material in 3D microtemplates: ALD [1], substrate surface, as shown below.

Polymer Gold

[1] V. Miikkulainen et al., J. Appl. Phys. 113, 021301 (2013); [2] M. Hermatschweiler et al., Adv. Funct. Mater. 17, 2273 (2007) [3] A. Radke et al., Adv. Mater. 23, 3018 (2011); [4] J. Gansel et al., Science 325, 1513 (2009)

8 Photonic Wire Bonds

Photonic Wire Bonds A novel concept for chip-to-chip interconnects

(Nicole Lindenmann) The demand for of Technology (KIT), Germany, has now Proof-of-principle devices exhibit ever higher data rates poses an increas- demonstrated a photonic chip-to-chip low losses at infrared telecommuni- ing challenge for electrical intercon- interconnect, a Photonic Wire Bond cation wavelengths around 1.55 µm nects. Fundamental limita­tions such (PWB), as they named it (1). This con- and permit transmission of data rates as size, speed and crosstalk call for a cept is illustrated in figure (a). exceeding 5 Tbit/s. This technological radically new approach, especially with Taking advantage of live imaging approach is considered a breakthrough regard to inter­chip connections. and three-dimensional writing capa- in optical interconnects. bility of the Photonic Professional, In this context, optical interconnects ­silicon-­on-insulator waveguides on are considered a promising candi- separate chips are connected by a R&D activities with the group of Prof. date to overcome communication freeform polymer PWB, figure (b). Christian Koos at KIT, with IBM and bottlenecks in data centers and high-­ The structure is formed by tightly Alcatel-Lucent (among others) have performance computers. However, focused femtosecond laser pulses that been government-funded (BMBF) while tremendous progress has been expose the photoresist precisely along within the project “Phoibos”. Please made in integrating optical transmit- the computed trajectory. The shape consult Nanoscribe for dedicated pho- ters and receivers on semiconductor of the wire bond is adapted to the tonic wire bonders for R&D as well as chips, there is currently no technology position and orientation of the chips, for large series production in industry. at hand that can cope with these chal- rendering high-precision mechanical lenges beyond chip edges. alignment unnecessary and bringing A group of researchers led by Prof. industrial­scale application of PWBs Christian Koos from Karls­ruhe Institute into reach, see figure (c).

Figure (a) Figure (b) Photonic Wire Bond SOI waveguides

Chip 1

Chip 2

Figure (c) Top view of multiple PWB

All pictures: Courtesy of Prof. Christian Koos, Karlsruhe Institute of Technology (KIT/IPQ), Germany Reference (1): N. Lindenmann, G. Balthasar, D. Hillerkuss, R. Schmogrow, M. Jordan, J. Leuthold, W. Freude, and C. Koos, “Photonic wire bonding: a novel concept for chip-scale interconnects,” Opt. Express 20, 17667-17677 (2012).

9 Mechanical Microstructures

Unfeelability Cloak Protects the Princess from the Pea Mechanical metamaterials open new dimensions

(Tiemo Bückmann) 3D galvo-scan- ner dip-in direct-laser-writing opti- cal lithography using Nanoscribe's Photonic­ Professional GT system allowed for the fabrication of mechan- ical metamaterial architectures with deep submicron features yet cubic milli- meter overall volumes at the same time. Using these we have designed, fabricated and characterized polymeric core-shell elastostatic unfeelability cloaks composed of as many as 1024 extended face-centered cubic unit cells. The high precision of the fabrica- tion was needed to adjust the mechan- ical properties of the surrounding and the cloaking shell to guide the forces around and let the solid cylinder vanish from being felt. On the other hand the millimeter scale overall volume was essential to char- acterize the cloak optically and get in 1 mm reach of possible applications.

It is like in Hans-Christian Andersen’s Mechanical invisibility cloak. Metamaterials protect objects on the lower side from being fairy tale about the princess and the felt. (Photo: T. Bückmann / KIT) pea. The princess feels the pea in spite With the finger or a force mea- of the mattresses. When using the surement instrument, no infor- cloak, however, one mattress would mation is obtained about the be sufficient for the princess to sleep bottom side of the material. well. The cloak shows that mechani- (Photo: T. Bückmann / KIT) cal metamaterials are a growing field using direct laser writing as only here the true three dimensionality and interesting size scales can be covered opening the door for interesting appli- cations.

To date, cloaking has been demon- strated experimentally in many fields of research, including electrodynam- Design of the mechanical core shell ics at microwave frequencies, optics, cloak showing the red cloaking shell and static electric conduction, acoustics, the fabricated surrounding in white. fluid dynamics, thermodynamics and (Image: T. Bückmann / KIT) quasi two-dimensional solid mechan- ics.

The results are presented in Nat. Com- mun. 5, 4130 (2014).

10 Metamaterials

3D Printed Micro-Trusses Strong as steel, but lighter than water

randomly which is not weight efficient, with respect to strength. ­Cancellous bone and other natural cellular sol- ids have an optimized architecture, designed adaptively to the loading sit- uation.

On the lowest level of hierarchy­ bone consists of nanometer-size building blocks, additionally ­providing strongly enhanced material strength because of mechanical size effects.

Designing cellular materials with a spe- cific microarchitecture allows one to exploit both structural advantageous mechanisms and size-dependent strengthening effects.

Applying 3D direct laser writing micro­architected lightweight mate- rials from ceramic-­polymer compos- ites have been fabricated (Fig.2) and mechanically characterized (Fig.3). Fig.1 Hexagonal micro-truss structure (colorized SEM image). Compressive loads correspon- Exceeding all technical and natu- ding to 550 kg/cm² may be carried, at a density less than the half of liquid water. ral materials with a density below 1000 kg/m³ as well as most metallic (Jens Bauer) Strong materials are heavy the nano-scale, certain porous biologi‑ alloys, ratios of strength-to-weight and light materials are weak. Strength cal materials such as bone and wood comparable to high-performance and density, two materials properties remain strong despite being extremely steels and technical ceramics are of central relevance for engineering, light, even though their basic material reached (Fig.1). are generally considered as strongly of which they are composed is gene­ coupled. However, nature shows us rally considered anything but strong. how we may overcome long stand- Light man-made materials such as ing barriers on the search for light yet technical foams on the other hand, strong materials. attain only limited mechanical pro­ Containing several levels of hier­ perties compared with corresponding Publication: PNAS (2014), doi: 10.1073/ archical structuring from the macro- to bulk materials. Foams are structured pnas.1315147111

Fig.2 left: Micro-truss structure from cera- mic-polymer composite (colorized­ SEM image), fabricated using 3D-DLW and atomic layer deposition. The miniaturized, specifically designed architecture allows benefiting from both structural advanta- ges and size-dependent material strengt- hening effects.

Fig.3 right: Deformed structure after uni- axial compression (colorized SEM image). Initial failure leads to a stackwise collapse. (Images: Jens Bauer / KIT)

11 Cell Biology

Cells Conquer the Third Dimension Cell cages for tissue engineering

In the last decades cells have been Technology (KIT), Germany, revealing satellites were created by polymeriza- intensively studied by biologists in the force of individual cells exerted in tion. After coating these islands with artificially structured two-dimen- a 3D topology. a protein that promotes cell adhesion, sional environments. In order to shine cells make contacts at these special even more light onto their behavior In the same group different photo- sites only. Thus, for the first time a in a rather natural environment 3D resists were combined to create a two-component functional scaffold scaffolds were created by means of fully functional 3D environment to for cells was 3D printed. ­Nanoscribe’s 3D printers. control the growth of single primary fibroblasts. First a mixture of PEG-DA In one of Nanoscribe's newsletters and PETA was used as a photoresist chicken heart cells beating in a 3D to create a stable core scaffold which scaffold were presented as an achieve- is non protein binding. After develop- ment of the group of Prof. Martin ment and refilling with the photoresist Bastmeyer at the Karlsruhe Institute of Ormocomp®, protein binding islands/

SEM images of cell scaffolds. White: struc- ture/cell core; green: actin cytoskeleton. F. Klein et al., Advanced Materials 23, 1341 (2011), “Two-Component Polymer Scaf- folds for Controlled Three-Dimensional­ Cell ­Culture”. Courtesy of Prof. Dr. Martin ­Bastmeyer, ­Benjamin Richter, Karlsruhe ­Institute of Tech- nology (CFN), ­Germany

Primary chicken fibroblasts adhering to protein-binding Ormocomp cubes. KIT/CFN, Prof. Dr. Martin Bastmeyer, F. Klein et al., Adv. Mater. 23, 1341 (2011)

12 Tissue Engineering

Bio-Inspired Osteoprints for the Enhancement of the Osteogenic Differentiation Tissue engineering via two-photon polymerization

(Attilio Marino) Several biophysical investigations suggest that a peculiar cell behavior can be in vitro resembled by mimicking the corresponding in vivo conditions. [1] In order to in vitro mimic the 3D natural microenvironment of the bone tissue we prepared, thanks to the slice-by-slice two-photon polymer- ization (2PP) approach, trabecula-like structures (named ‘‘Osteoprints’’) that resemble the typical microenviron- ment of trabecular bone cells. [2]

Particularly, the 3D model of the Osteoprint was obtained from X-ray micro-computed tomography (µ-CT) scans of a human trabecular bone biopsy, taken from the femoral neck (Fig. 1). Osteoprints were subsequently fabricated through 2PP of the biocom- patible ceramic photopolymer Ormo- comp®, the mechanical properties of which are similar to that of the natu- ral bone. SEM imaging (Fig. 2) of the obtained Osteoprints reveals a shape and size exactly resembling those of the corresponding 3D µ-CT model, thus demonstrating the high resolution and Fig. 1: 3D reconstruction of bone trabeculae obtained by µ-CT scans of a biopsy from the reliability of the 2PP technique. human femoral neck. After an extensive Osteoprint charac- terization, the adhesion, proliferation and differentiation of SaOS-2 osteo- up-regulation of the genes involved on range of in vitro application and even blast-like cells were studied on the osteogenesis and an enhancement of in tissue engineering and regenerative obtained scaffolds. the hydroxyapatite nodule production medicine. [3] were the major outcomes (Fig. 3). The presence of the Osteoprints was This article was provided by Nano- able to deeply affect cell behavior, These results encourage the exploita- scribe’s customer, the Italian Insti- promoting the cell cycle exit and tion of the 2PP for obtaining 3D bio- tute of Technology, Center for Micro- the osteogenic differentiation. An mimetic structures, useful for a wide BioRobotics @SSSA.

References: [1] A. Marino, C. Filippeschi, V. Mattoli, B. Mazzolai and G. Ciofani, Nanoscale, 2015, 07, 2815–3320. [2] A. Marino, C. Filippeschi, G. G. Genchi, V. Mattoli, B. Mazzolai and G. Ciofani, Acta Biomater., 2014, 10, 4303– 4313. [3] S. D. Gittard, A. Koroleva, A. K. Nguyen, E. Fig. 2: SEM imaging of an Osteoprint pre- Fig. 3: 3D reconstruction of a bone cell cul- pared by slice-by-slice 2PP of the hybrid ture on the Osteoprint (in red), highligh- Fadeeva, A. Gaidukeviciute, S. Schlie-Wolter, ceramic Ormocomp® photoresist. ting the deposition of several hydroxyapa- R. J. Narayan and B. Chichkov, Front. Biosci. tite nodules (in green). Elite Ed., 2013, 5, 602–609.

13 Micromachines

Magnetic Helical Micromachines Fabrication, controlled swimming, and cargo transport

(Li Zhang) Helical micro-swimmers in liquids were driven by a rotating inspired by bacterial flagella have been magnetic field at rotating frequencies successfully realized by researchers of several 10 Hz at a few mT, enabling surrounding the group of Brad Nelson accurately steerable movement in 3D at the ETH Zürich. with velocities up to several 100 µm/s.

Making use of the flexibility of the This additionally was topped by cargo Photonic Professional GT 3D direct transport where microspheres were laser writing system micron-sized loaded, transported and unloaded ­helices with and without microholders from a basket (figure 3, 4). were written and subsequently coated with ferromagnetic nickel (figure 1, 2). No doubt: The researchers obviously In order to enable the use in biological enjoy that topic spending late hours in applications, the surface was further- the lab – as seen in the time stamp of more coated with a thin titanium layer the recorded videos! Who would prefer in order to reduce potential cytotoxic going home to your playstation if you effects. Thus, corkscrew-like motions have such a research-tool in your lab?

Figure (1) Advanced Materials, Volume 24, Issue 6, 811–816 (2012), © Wiley-VCH Verlag GmbH & Co. KGaA, reproduced with permission.

Figure (2)

Figure (3)

2 µm

Images by courtesy of ETH Zürich

Figure (4)

www.youtube.com/watch?v=sJP4rL57Dq8

14 Micro Rapid Prototyping

Rapid Prototyping of Micro- and Mesoparts Two-photon polymerization transfers the benefits of 3D printing to the microscale.

Following the trend of miniaturization 3D printing on the microscale needs to provide excellent resolution to allow for the fabrication of finest features. Micro-sized parts have a great poten- tial in a wide variety of applications like optics, photonics, biotechnology, life-sciences, micro­fluidics and many more. For applications where compo- nents and devices with feature-sizes on the micro/meso-scale (10² - 104 µm) are needed, additive manufacturing based on two-photon polymerization provides the necessary resolution to transfer the benefits of 3D printing to this scale. Among these advantages are cost-effective production of complex structures and functional integration for low volume production down to a lot size of one. 1 mm

In a recent publication of Optics 3D printed micro connectors. Express*, researchers from the Arizona State University demonstrated the ben- efits of highest-resolution 3D printing for the fabrication of complex shaped nozzles that are directly used for their experimental work. For biological imag- ing using X-ray Free Electron Lasers, the use of gas dynamic virtual nozzles has proven to be valuable method for reliable sample delivery. However, the standard method of fabricating these nozzles manually represents a cumbersome and error prone process. 1 mm 1 mm The researchers successfully used a Photonic­ Professional GT to consoli- Mechanical mixer structure with filigree Porous lattice tower. date several manual fabrication steps mixer blades. into one single automatic 3D printing step. The high-resolution 3D printing of polymer micro nozzles from CAD data enables the researchers to not only gain flexibility for design iterations but also to reduce the quality variances inherent in the standard manual fab- rication method. As demonstrated by testing the jetting behavior, these ­nozzles provide high quality per- formance and have the potential to become the new standard in this field of research. 100 µm 100 µm Further examples of mesoscopic struc- tures are demonstrated in the image Rendering of the STL with a cut-out to show the inner complexity of the nozzle design (left) gallery on the right side. and the final 3D print from the STL (right). Optics* Express, Vol 24, Issue 11, pp. 11515 (2016)

15 Nanoscribe GmbH Founded in 2007 as a spin-off from the Karlsruhe Institute Hermann-von-Helmholtz-Platz 1 of Technology, Germany, and as a pioneer in the field of 76344 Eggenstein-Leopoldshafen two-photon polymerization, Nanoscribe has established Germany itself globally as market and technology leader in 3D printing on the nano-, micro- and mesoscale. Today it is Phone +49 721 981 980 0 ranked among the most successful young medium-sized Fax +49 721 981 980 130 companies in Germany. E-Mail [email protected] Top institutions in academia as well as pioneers in industry Web www.nanoscribe.com in more than 30 countries worldwide already successfully use this new, award-winning standard for microfabrication.

On our website, you can find a multitude of examples for the broad range of applications as well as a long list of scientific papers published by our users. The close contact to our customers is supported by a worldwide sales and service network. Rapid and first-class

customer service is a matter of course for us. FL/AP_FO/V08_2018