DOCSLIB.ORG

Electret Nanogenerators for Self-Powered, Flexible Electronic Pianos

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electret Nanogenerators for Self-Powered, Flexible Electronic Pianos sustainability Article Electret Nanogenerators for Self-Powered, Flexible Electronic Pianos Yongjun Xiao 1, Chao Guo 2, Qingdong Zeng 1, Zenggang Xiong 1, Yunwang Ge 2, Wenqing Chen 2, Jun Wan 3,4,* and Bo Wang 2,* 1 School of Physics and Electronic-Information Engineering, Hubei Engineering University, Xiaogan 432000, China; [email protected] (Y.X.); [email protected] (Q.Z.); [email protected] (Z.X.) 2 School of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023, China; [email protected] (C.G.); [email protected] (Y.G.); [email protected] (W.C.) 3 State Key Laboratory for Hubei New Textile Materials and Advanced Processing Technology, Wuhan Textile University, Wuhan 430200, China 4 Hubei Key Laboratory of Biomass Fiber and Ecological Dyeing and Finishing, School of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan 430200, China * Correspondence: [email protected] (J.W.); [email protected] (B.W.) Abstract: Traditional electronic pianos mostly adopt a gantry type and a large number of rigid keys, and most keyboard sensors of the electronic piano require additional power supply during playing, which poses certain challenges for portable electronic products. Here, we demonstrated a fluorinated ethylene propylene (FEP)-based electret nanogenerator (ENG), and the output electrical performances of the ENG under different external pressures and frequencies were systematically characterized. At a fixed frequency of 4 Hz and force of 4 N with a matched load resistance of 200 MW, an output 2 power density of 20.6 mW/cm could be achieved. Though the implementation of a signal processing circuit, ENG-based, self-powered pressure sensors have been demonstrated for self-powered, flexible Citation: Xiao, Y.; Guo, C.; Zeng, Q.; electronic pianos. This work provides a new strategy for electret nanogenerators for self-powered Xiong, Z.; Ge, Y.; Chen, W.; Wan, J.; sensor networks and portable electronics. Wang, B. Electret Nanogenerators for Self-Powered, Flexible Electronic Keywords: electret; nanogenerator; self-powered; flexible; electronic piano Pianos. Sustainability 2021, 13, 4142. https://doi.org/10.3390/su13084142 Academic Editor: Peihua Yang 1. Introduction With the massive development of electronic technology, especially in smart and wear- Received: 15 February 2021 able electronics, implantable electronic devices, patient monitoring, distributed wireless Accepted: 23 March 2021 Published: 8 April 2021 sensor networks, environmental and structure monitoring, and national security, etc., har- vesting energy from the human body and the ambient environment is a suitable solution Publisher’s Note: MDPI stays neutral for the rapid and constant increase of the world’s energy demand. Meanwhile, there is with regard to jurisdictional claims in ubiquitous kinetic energy in various motions and vibrations: for example, human motion, published maps and institutional affil- walking, vibration, mechanical triggering, rotating tires, wind, flowing water, and more. iations. Therefore, harvesting mechanical energy from the living environment to establish a sus- tainable and maintenance-free electronic system has become a research hotspot in the last two decades [1–3]. New technologies that can harvest energy from the environment as self-sufficient micro/nano-power sources are newly emerging fields of nanoenergy, which is about the applications of nanomaterials and nanotechnology for harvesting energy for Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. powering micro/nanosystems [4,5]. This article is an open access article Electronic pianos are widely used in modern music performances, people’s learning distributed under the terms and and entertainment due to their wide range of sound, abundant harmony, multi-tone conditions of the Creative Commons imitation, free volume regulation, rhythm accompaniment similar to percussion sound, Attribution (CC BY) license (https:// and additional effects such as reverberation, echo, delay, vibrators and modulators, etc. [6,7]. creativecommons.org/licenses/by/ In general, traditional electronic pianos mostly adopt a gantry type and a large number 4.0/). of rigid keys, which occupy a large space, and thus the whole system is inconvenient to Sustainability 2021, 13, 4142. https://doi.org/10.3390/su13084142 https://www.mdpi.com/journal/sustainability Sustainability 2021, 13, 4142 2 of 10 carry. In addition, most of the keyboard sensors of the electronic piano require additional power supply during playing, which poses certain challenges for portable applications that continue to work. For instance, the theremin, the first electronic instrument, produced in 1928, uses capacitive sensors as the interface, and additional power consumption is inevitable [8]. Therefore, to realize a portable and sustainable electronic piano, flexible and self-powered pressure sensors should be endowed to the keyboard of the smart electronic piano, which is small in size, easy to carry, and maintenance-free [9]. Up to now, pressure sensors with various sensing mechanisms such as piezoresis- tivity [10–14], capacitance [15–17], piezoelectricity [18–20], and triboelectricity [21–23] have been successfully demonstrated in the last two decades. Among these, resistive and capacitive sensors require peripheral auxiliary circuits to power the sensors to achieve the required parameters, while piezoelectric and triboelectric sensors can output a certain voltage or current signal directly without the need for external equipment under the stimuli of external force [24,25]. However, piezoelectric sensors depend on the characteristics of the piezoelectric materials used. Although the performance of traditional piezoelectric ceramics such as lead zirconate titanate (PZT) have high piezoelectric coefficients (up to 700 pC/N) [26], their intrinsic brittleness limits their application in flexible electronics. The flexible piezoelectric polymers, polyvinylidene fluoride (PVDF) and its co-polymers, have better flexibility and mechanical toughness, but the piezoelectric coefficients d33 are only dozens of pC/N [27]. In recent years, triboelectric nanogenerators have been designed and used to harvest mechanical energy from the working environment of the device to directly power the device, forming a trend of self-powered systems for application in micro- electromechanical converters, especially in portable/wearable personal electronics [28]. The basic working mechanism of triboelectric nanogenerators is the coupling effects be- tween triboelectrification and electrostatic induction through the contact-separation or relative sliding between two dielectric materials that have opposite electron affinities. The area power density of the devices can reach up to 1200 W/m2, and thus the output performance is high enough and very suitable to be used to design self-powered, active mechanical/vibrational sensors for flexible electronics [29]. Specially, the active materials of the nanogenerators that usually have a strong triboelectric effect are likely less conductive or insulators, so most of them can be classified into electrets, which are dielectric materials exhibiting quasi-permanent charges [30]. Electret nanogenerators are superior due to their light weight, high output performance, and good resistance to high temperatures and high humidity, which makes them very suitable for self-powered pressure sensing electronic devices [31–33]. In this work, an electret nanogenerator (ENG) was prepared using fluorinated ethylene propylene (FEP) electret and indium tin oxide/polyethylene terephthalate (ITO/PET), forming an arch-shaped structure. The output electrical performances of the ENG under different external pressures and frequencies were systematically characterized. Under the external pressure of 4 N and frequency of 4 Hz with a matched load resistance of 200 MW, the as-fabricated ENG could achieve a maximum power density of 20.6 µW/cm2. In addition, ENG-based self-powered pressure sensors were mounted onto the keyboard of a flexible electronic piano, and a signal processing system was demonstrated to realize the application of a flexible electronic piano. This work provides a new strategy to fabricate smart electronic pianos, indicating its promising applications in artificial intelligence and smart electronic devices. 2. Materials and Methods 2.1. Fabrication Process of the ENG In the first step, a piece of FEP film (DuPont FEP50) was cut into a rectangular shape with an area of 4 × 1.3 cm2, followed by corona charging under a high voltage of −15 kV for 5 min. In the second step, a piece of PI substrate was cut in accordance to the same size of the FEP, and then a 60 nm copper electrode was stuck on its upper side. In the third step, the FEP film was tightly bonded to the copper electrode of the polyimide (PI) Sustainability 2021, 13, 4142 3 of 10 substrate, and both ends of the ITO/PET film were bonded to the FEP film by double- sided adhesive to form an arch-shaped structure [34]. All films were rinsed with alcohol before measurement. 2.2. Fabrication of Electronic Piano Firstly, a flexible PCB substrate was designed using CAD software. Specifically, seven pieces of copper-clad pad with an area of 4 × 1.3 cm2 and a thickness of 60 nm were pasted on a flexible PI substrate, which were connected to the seven terminals of the flexible wire interface, respectively. Subsequently, a common copper-clad pad was installed on the PI film as the common ground electrode, which was connected with the eighth terminal
Load more

Recommended publications
  • Introduction to Electrets: Principles, Equations, Experimental Techniques
    Introduction to electrets: Principles, equations, experimental techniques Gerhard M. Sessler Darmstadt University of Technology Institute for Telecommunications Merckstrasse 25, 64283 Darmstadt, Germany [email protected] Darmstadt University of Technology • Institute for Telecommunications Overview Principles Charges Materials Electret classes Equations Fields Forces Currents Charge transport Experimental techniques Charging Surface potential Thermally-stimulated discharge Dielectric measurements Charge distribution (surface) Charge distribution (volume) Darmstadt University of Technology • Institute for Telecommunications Electret charges Darmstadt University of Technology • Institute for Telecommunications Energy diagram and density of states for a polymer Darmstadt University of Technology • Institute for Telecommunications Electret materials Polymers Anorganic materials Fluoropolymers (PTFE, FEP) Silicon oxide (SiO 2) Polyethylene (HDPE, LDPE, XLPE) Silicon nitride (Si 3N4) Polypropylene (PP) Aluminum oxide (Al 2O3) Polyethylene terephtalate (PET) Glas (SiO 2 + Na, S, Se, B, ...) Polyimid (PI) Photorefractive materials Polymethylmethacrylate (PMMA) • Polyvinylidenefluoride (PVDF) • Ethylene vinyl acetate (EVA) • • • Cellular and porous polymers Cellular PP Porous PTFE Darmstadt University of Technology • Institute for Telecommunications Charged or polarized dielectrics Category Materials Charge or polarization Properties Applications Density Geometry [mC/m2 ] Real-charge External electric FEP, SiO electrets 2 0.1 - 1 field
    [Show full text]
  • Note PERFORMANCE of ELECTRET IONIZATION CHAMBERS IN
    Note PERFORMANCE OF ELECTRET IONIZATION CHAMBERS IN MAGNETIC FIELD P. Kotrappa,* L. R. Stieff,* T. F. Mengers,† and R. D. Shull† The change in charge is measured using a portable charge Abstract—Electret ionization chambers are widely used for reader and is the measure of the integrated ionization measuring radon and radiation. The radiation measured in- cludes alpha, beta, and gamma radiation. These detectors do over the sampling period. These chambers are widely not have any electronics and as such can be introduced into used for measuring radon in air (Kotrappa et al. 1990) magnetic field regions. It is of interest to study the effect of and environmental gamma radiation (Fjeld et al. 1994; magnetic fields on the performance of these detectors. Relative Hobbs et al. 1996). These chambers are also used for responses are measured with and without magnetic fields present. Quantitative responses are measured as the magnetic measuring alpha and beta contamination levels (Kasper field is varied from 8 kA/m to 716 kA/m (100 to 9,000 gauss). 1999; Kotrappa et al. 1995). One feature of these No significant effect is observed for measuring alpha radiation detectors, which makes them unique, is that there are no and gamma radiation. However, a significant systematic effect electronic components or power supply associated with is observed while measuring beta radiation from a 90Sr-Y source. Depending upon the field orientation, the relative the detectors. Because of this property, these detectors response increased from 1.0 to 2.7 (vertical position) and can be used in areas with magnetic fields present without decreased from 1.0 to 0.60 (horizontal position).
    [Show full text]
  • How to Make an Electret the Device That Permanently Maintains an Electric Charge by C
    How to Make an Electret the Device That Permanently Maintains an Electric Charge by C. L. Strong Scientific America, November, 1960 Danger Level 4: (POSSIBLY LETHAL!!) Alternative Science Resources World Clock Synthesis Home --------------------- THE HISTORY OF SCIENCE IS A TREASURE house for the amateur experimenter. For example, many devices invented by early workers in electricity and magnetism attract little attention today because they have no practical application, yet these devices remain fascinating in themselves. Consider the so-called electret. This device is a small cake of specially prepared wax that has the property of permanently maintaining an electric field; it is the electrical analogue of a permanent magnet. No one knows in precise detail how an electret works, nor does it presently have a significant task to perform. George O. Smith, an electronics specialist of Rumson, N.J., points out, however, that this is no obstacle to the enjoyment of the electret by the amateur. Moreover, the amateur with access to a source of high-voltage current can make an electret at virtually no cost. "For more than 2,000 years," writes Smith, "it was suspected that the magnetic attraction of the lodestone and the electrostatic attraction of the electrophorus were different manifestations of the same phenomenon. This suspicion persisted from the time of Thales of Miletus (600 B.C.) to that of William Gilbert (A.D. 1600). After the publication of Gilbert's treatise De Magnete, the suspicion graduated into a theory that was supported by many experiments conducted to show that for every magnetic effect there was an electric analogue, and vice versa.
    [Show full text]
  • Charge Storage in Electret Polymers: Mechanisms, Characterization and Applications
    Charge Storage in Electret Polymers: Mechanisms, Characterization and Applications Habilitationsschrift zur Erlangung des akademischen Grades doctor rerum naturalium habilitatus (Dr. rer. nat. habil.) der Mathematisch-Naturwissenschaftlichen Fakult¨at der Universit¨at Potsdam vorgelegt von Dr. Axel Mellinger geb. am 25. August 1967 in M¨unchen Potsdam, 06. Dezember 2004 iii Abstract Electrets are materials capable of storing oriented dipoles or an electric surplus charge for long periods of time. The term “electret” was coined by Oliver Heaviside in analogy to the well-known word “magnet”. Initially regarded as a mere scientific curiosity, electrets became increasingly imporant for applications during the second half of the 20th century. The most famous example is the electret condenser microphone, developed in 1962 by Sessler and West. Today, these devices are produced in annual quantities of more than 1 billion, and have become indispensable in modern communications technology. Even though space-charge electrets are widely used in transducer applications, relatively little was known about the microscopic mechanisms of charge storage. It was generally accepted that the surplus charges are stored in some form of physical or chemical traps. However, trap depths of less than 2 eV, obtained via thermally stimulated discharge experiments, conflicted with the observed lifetimes (extrapolations of experimental data yielded more than 100 000 years). Using a combination of photostimulated discharge spectroscopy and simultaneous depth-profiling of the space-charge density, the present work shows for the first time that at least part of the space charge in, e. g., polytetrafluoroethylene, polypropylene and polyethylene terephthalate is stored in traps with depths of up to 6 eV, indicating major local structural changes.
    [Show full text]
  • Piezoelectricity in Cellular Electret Films
    IEEE Transactions on Dielectrics and Electrical Insulation Vol. 7 No. 4, August 2000 537 Piezoelectricity in Cellular Electret Films J. Hillenbrand and G. M. Sessler Institute for Communications Technology Darmstadt University of Technology Darmstadt, Germany ABSTRACT Permanently charged films with a cellular or porous structure represent a new family of poly- mer electrets. These materials show piezoelectric properties with high piezoelectric constants. The electromechanical response equations of such films are derived for their operation as sen- sors and as actuators. Experimental results are also presented for cellular polypropylene (PP). In particular, measurements of the direct and inverse piezoelectric constants in the frequency range 0 to 10 kHz and of the variation of these constants across the surface of the films are dis- cussed. These measurements, performed by direct application of stress or by the use of a pro- filometer, an accelerometer and an interferometer yield a frequency-independent piezoelectric $33 constant of 5 220 pC1N. Assuming reasonable charge distributions and charge densities, the calculated piezoelectric constants are in good agreement with the measured values. The theoretical model shows the reciprocity of the piezoelectric constants. 1 INTRODUCTION The charged material, electroded on top and bottom, consists of plane parallel solid layers and air layers of thicknesses SI, and sa,, respec- HERE has been considerable recent interest in the permanent tively, with n = 1,2,.. iV and m, = I, 2, . N - I, where N is charging of films with a cellular or porous structure [l-151. It T the total number of solid layers. It is further assumed that the two solid was shown that such films of polypropylene (PP), polytetrafluoroethy- surfaces confining the m-th air layer carry a total planar charge density lene, and silicon dioxide, when charged with corona or other methods, of om and -oTn,respectively, and that no volume charges exist.
    [Show full text]
  • Magneto Electret State of Porous Polypropylene and Investigation on Surface Charge Characteristics
    IOSR Journal of Applied Physics (IOSRJAP) ISSN – 2278-4861 Volume 1, Issue 1 (May-June 2012), PP 131-136 www.iosrjournals.org Magneto electret State of Porous Polypropylene and Investigation on Surface Charge Characteristics Pragya Ojha1, M. S. Qureshi2, M. M. Malik3 1, 2, 3(Electret research laboratory, Department of Physics, MANIT, Bhopal 462051, India) Abstract : This paper reports preparation of porous polypropylene magneto electret and its investigation on its surface charge characteristics. The electrets were prepared under the combined action of heat and magnetic field. Influences of polarizing temperature and magnetic field on MEs state of polypropylene were studied. Five different forming temperatures and five different magnetic field strength were used for the surface charge study of magnetoelectrets. Surface charge was found to be of the order of 10-10C. Negative iso charge was found in all the magnetoelectrets. The decay of surface charge was studied continuously for 30 days and corresponding time constant were calculated. Keywords - Dielectric, Magnetoelectrets (MEs), porous polypropylene, magnetic field, surface charge. I. INTRODUCTION Dielectric samples showing persistent polarization is termed as ‘Electrets’ [1] in analogy with magnet because in many ways an electret is the electrostatic counterpart of magnet. The first electret resembling Heaviside’s was prepared by Eguchi [2] by solidifying the molten mixture of carnauba wax and resin in an intense electric field. In an electret, the dielectric is in state of persistent polarization, i.e. the polarized state continues to stay in the dielectric for considerably long time even after the removal of polarizing field. Electrets are classified depending on the physical agency that produces polarization in dielectric under the influence of an external field.
    [Show full text]
  • Electrostatics in Material
    Electrostatics in material Bound charges Laplacean methods and dielectrics θ q zˆ ˆ z ˆ η zˆ Z ηˆ PPz= 0 ε 0 σ R E zˆ R s b ε 0 α ε Image methods Separation of variables ε I D top σ Displacement f Q σb < 0 field V r Stored E ε d energy in a dielectric Dbottom σb > 0 −σ above f E ε 0 Dielectric below E ε ε 0 F Forces d ε H Dielectric boundary F conditions 1 x − x xˆ From Physics 212, one might get the impression that going from electrostatics in vacuum to electrostatics in a material is equivalent to replacing epsilon_0 to epsilon > epsilon_0. This is more-or-less true for some dielectric materials such as Class A dielectrics but other types of materials exist. For example, there are permanent electrets which are analogous to permanent magnets. Here the electric field is produced by “bound” charges created by a permanently “frozen-in” polarizability. The polarizability is the electric dipole moment per unit volume that is often induced in the material by an external electric field. We will introduce the displacement field (or D-field) which obeys a Gauss’s Law that only depends on free charges. Free charges are the charges controllable by batteries, currents and the like. To a large extent one cannot totally control bound charges. We discuss the boundary conditions that E-fields and D-fields obey across a dielectric boundary. We turn next to a discussion of Laplace’s Equation in the presence of dielectrics.
    [Show full text]
  • IT ALL STARTS with the MICROPHONE Things You Were Never Told
    IT ALL STARTS WITH THE MICROPHONE THINGS YOU WERE NEVER TOLD $10 BOB HEIL PreFace Have you ever had the experience of a using a very expensive sound system and the sound was still awful? Have you ever been at a concert and not been able to understand the singer? Or been at a football game and not been able to understand the announcer? These are often examples of poor or improper use of the microphones—the source of all sound in modern sound systems. The microphone is the single most important piece of equipment in nearly every audio chain. You can have a very expensive sound system and if you do not understand how to use a microphone, the sound will be terrible. The quality of sound at the end (your ears) depends on the quality at the beginning. If you work with sound, it is essential that you have a thorough grasp of how microphones work, the different types of microphones and what they do. How a microphone sounds and behaves in a particular situation will significantly affect your success in achieving “good” sound. This publication is targeted at educating those of us who use microphones every day yet may not be technical whiz kids. While sound does involve physics, the basic understanding of microphones is not rocket science! We will bring new and informative “light” to the subject of mics, and also discuss and define issues that affect them and their surroundings. You will discover important information that will help you get the most from your microphones and improve the sound you work with.
    [Show full text]
  • Electrostatic MEMS Vibration Energy Harvesters Inside of Tire Treads
    sensors Article Electrostatic MEMS Vibration Energy Harvesters inside of Tire Treads Yasuyuki Naito 1,* and Keisuke Uenishi 2 1 Institute for Energy and Material Food Resources, Technology Innovation Division, Panasonic Corporation, Kyoto 619-0237, Japan 2 Department of Management of Industry and Technology, Graduate of School of Engineering, Osaka University, Osaka 561-0871, Japan; [email protected] * Correspondence: [email protected]; Tel.: +81-774-98-2580 Received: 27 December 2018; Accepted: 19 February 2019; Published: 21 February 2019 Abstract: An electret electrostatic MEMS vibration energy harvester for tire sensors mounted inside of the tire tread is reported. The device was designed so as to linearly change an electrostatic capacitance between the corrugated electret and output electrode according to the displacement of the proof mass. The electromechanical linearity was effective at reducing the power loss. The output power reached 495 µW under sinusoidal vibration despite the footprint size being as small as 1 cm2. Under impact vibration inside of the tire tread, the output power reached 60 µW at a traveling speed of 60 km/h. It was revealed that a higher mechanical resonance frequency of the harvester adjusted within the frequency band of a low-power spectral density of impact vibration acceleration was effective for high efficiency harvest impact vibration energy. Keywords: power MEMS; vibration energy harvester; electret electrostatic; TPMS; tire sensor 1. Introduction In order to improve the driving safety of automobiles, the requirements of tire pressure monitoring systems (TPMS) have advanced worldwide, starting with the United States and Europe. A tire sensor with the TPMS inside of tire tread enables gathering information of the road surface and tires for the detection of the degree of slippage.
    [Show full text]
  • Understanding and Modeling of Triboelectric-Electret Nanogenerator
    Nano Energy 47 (2018) 401–409 Contents lists available at ScienceDirect Nano Energy journal homepage: www.elsevier.com/locate/nanoen Full paper Understanding and modeling of triboelectric-electret nanogenerator T ⁎ Ronan Hincheta, Ali Ghaffarinejadb,c, Yingxian Lub, Javad Yavand Hasanic, Sang-Woo Kima, , ⁎ Philippe Bassetb, a School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea b Université Paris-Est, ESYCOM, ESIEE Paris, Noisy-le-Grand 93162, France c School of Electrical Engineering, Iran University of Science and Technology, Tehran 16846-13114, Iran ARTICLE INFO ABSTRACT Keywords: Recently, electrostatic kinetic energy harvesters regained strong attention through the development of new Triboelectric nanogenerator triboelectric generators for harvesting green and renewable energy. These devices use a triboelectric dielectric Kinetic energy harvester layer as electret for polarizing their capacitance and they behave similarly to electret generators. However, Triboelectric generator simulation triboelectric-based electret nanogenerators (T-ENG) have specificities arising from the contact electrification Triboelectric-electret (triboelectret) phenomenon and leading to different performances. For better understanding T-ENG, we investigated their nanogenerator electrical modeling with lumped-elements and multiphysics simulation in light of last researches on electret T-ENG generators. To take into account T-ENG specificities, we experimentally measured the amplitude of the tribo- electric effect on perfluoroalkoxy alkane films. This approach allowed fully simulating T-ENG and the model was found in agreement with experimental results. Understanding and verifying the model is capital, but to go further toward the application of T-ENG, we reused two electret circuits to extract the T-ENG model parameters in view of facilitating their realistic modeling and practical development into application.
    [Show full text]
  • Piezo- and Pyroelectric Properties of Electreta
    NBSIR 75-787 Piezo- and Pyroelectric Properties of Electrets Martin G. Broadhurst and G. Thomas Davis Institute for Materials Research National Bureau of Standards Washington, D. C. 20234 October 1975 Final - January 1, 1975 - December 31, 1975 Prepared for Office of Naval Research Chemistry Program Arlington, Va. 22044 NBSIR 75-787 PIEZO- AND PYROELECTRIC PROPERTIES OF ELECTRETA Martin G. Broadhurst and G. Thomas Davis Institute for Materials Research National Bureau of Standards Washington, D. C. 20234 October 1975 Final - January 1, 1975 - December 31, 1975 Prepared for Office of Naval Research Chemistry Program Arlington, Va. 22044 U.S. DEPARTMENT OF COMMERCE, Rogers C.B. Morton, Secretary James A. Baker, III, Under Secretary Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director PIEZO- AND PYROELECTRIC PROPERTIES . G. Broadhurst and G. T. Davis National Bureau of Standards Washington, D, C. 20234 4. Piezoelectric and Pyroelectric Properties Introduction 4 . 1 Thermodynamics 4.2 Electret Description 4.21 Preparation of a polar electret 4.22 Real Charges 4.23 Dipole Charges 4.3 Tensor Rotation 4.4 Structure 4.4.1 General 4.4.2 Amorphous Polymers 4.4.3 Semicrystalline Polymers 4.4.4 Molecular Structure 4.4.5 Bulk Structure 4.4.6 Crystal Phases 4.5 Properties 4.5.1 Crystal Relaxations 4.5.2 Ferroelectricity ^.5.3 Space Charges 4.6 Measurements and Data 4.7 Dipole Model for Semicrystalline Polymers 4.8 Summary and Conclusions Oliver Heavside [4.1] in 1892, postulated that certain waxes would form permanently polarized dielectrics when allowed to solidify from the molten state in the presence of an electric field.
    [Show full text]
  • Tunable Polytetrafluoroethylene Electret Films with Extraordinary
    www.nature.com/scientificreports OPEN Tunable polytetrafuoroethylene electret flms with extraordinary charge stability synthesized by Received: 28 September 2018 Accepted: 18 December 2018 initiated chemical vapor deposition Published: xx xx xxxx for organic electronics applications Stefan Schröder1, Thomas Strunskus 1, Stefan Rehders1, Karen K. Gleason2 & Franz Faupel 1 Bulk polytetrafuoroethylene (PTFE) possesses excellent chemical stability and dielectric properties. Indeed, thin flms with these same characteristics would be ideal for electret applications. Previously, the electret properties of PTFE-like thin flms produced by rf sputtering or plasma enhanced chemical vapor deposition were found to deteriorate due to structural changes and surface oxidation. In this article, the technique of initiated chemical vapor deposition (iCVD) is evaluated for electret applications for the frst time. The iCVD method is known for its solvent-free deposition of conformal, pinhole-free polymer thin flms in mild process conditions. It is shown that PTFE thin flms prepared in this way, show excellent agreement to commercial bulk PTFE with regard to chemical properties and dielectric dissipation factors. After ion irradiation in a corona discharge the iCVD PTFE thin flms exhibit stable electret properties, which can be tailored by the process parameters. Due to the mild deposition conditions, the iCVD technique is suitable for deposition on fexible organic substrates for the next- generation electret devices. It is also compatible with state-of-the-art microelectronic processing lines due to the characteristics of conformal growth and easy scaling up to larger size substrates. Besides its excellent chemical stability and dielectric properties polytetrafuoroethylene (PTFE) is well known for its outstanding performance as a real charge electret material1–3.
    [Show full text]