Electroactive Polymers

Boron doped and undoped Poly(vinyl) alcohol/Zirconium-yttrium acetate (PVA/Zr-Y) nanofibers were prepared by electrospinning using PVA as a precursor. The effect of boron doping was investigated in terms of solution properties, morphological changes and thermal properties. The effect of boron doping on calcined yttria stabilized zirconia (YSZ) fibers were evaluated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy analysis. XRD
analysis revealed varying amounts of monoclinic and tetragonal zirconia present in the undoped fibers calcined at 800oC. The average crystallite sizes of the undoped YSZ were increased from 9.28 to 22.79 nm with calcining temperature increasing from 250 to 800 °C. The crystallite size was enhanced with boron doping. The systematic evolution of morphological features in the spun and the processed fibers were employed by scanning electron microscopy.

Listrik merupakan salah satu kebutuhan yang sangat penting bagi kehidupan manusia. Tanpa adanya listrik, akan sulit bagi kita untuk melakukan suatu aktifitas dalam kehidupan sehari-hari. Wilayah kawasan hutan lindung Kuta Malaka Kabupaten Aceh Besar merupakan salah satu wilayah yang sulit terjangkau listrik negara. Kuta Malaka terkenal dengan sirkuit offroadnya, air terjun yang sangat indah, perkebunan buah naga dan stroberi dan hutan lindung yang masih sangat alami . Maka pemerintah dan masyarakat setempat rencananya akan membangun daerah tersebut menjadi daerah objek wisata alam. Akan tetapi, karena belum tersedianya pasokan listrik dari PT. PLN, maka objek wisata alam tersebut mengalami beberapa hambatan dalam pembangunannya. Karena di Kuta Malaka memiliki potensi air, maka rencananya di Kuta Malaka akan memanfaatkan pembangkit listrik ramah lingkungan yaitu Pembangkit Listrik Tenaga Mikro Hidro (PLTMH) sebagai sumber pasokan energi listriknya. Berdasarkan survei potensi yang dilakukan oleh Pusat Penelitian Tenaga Listrik dan Mekatronik (LIPI) di Kuta Malaka, head effektif yang dapat dimanfaatkan yaitu 5 meter dengan debit desain 0,130 m 3 /s. Hasil perancangan untuk daya output turbin 3,7 kW dan daya output generator 3,14 kW diperoleh diameter runner 244 mm, diameter bush 85 mm, diameter shaft 37 mm, jarak antar sudu 192 mm, serta menggunakan kopling jenis flens dan generator induksi tipe ELC (Electronic Load Controller).

Rapid prototyping in the design cycle of new microfluidic devices is very important for shortening time-to-market. Researchers are facing the challenge to explore new and suitable substrates with simple and efficient microfabrication techniques. In this paper, we introduce and characterize a UV-curing elastomeric polyurethane methacrylate (PUMA) for rapid prototyping of microfluidic devices. The swelling and solubility of PUMA in different chemicals is determined. Time-dependent measurements of water contact angle show that the native PUMA is hydrophilic without surface treatment. The current monitoring method is used for measurement of the electroosmotic flow mobility in the microchannels made from PUMA. The optical, physical, thermal and mechanical properties of PUMA are evaluated. The UV-lithography and molding process is used for making micropillars and deep channel microfluidic structures integrated to the supporting base layer. Spin coating is characterized for producing different layer thicknesses of PUMA resin. A device is fabricated and tested for examining the strength of different bonding techniques such as conformal, corona treating and semi-curing of two PUMA layers in microfluidic application and the results show that the bonding strengths are comparable to that of PDMS. We also report fabrication and testing of a three-layer multi inlet/outlet microfluidic device including a very effective fluidic interconnect for application demonstration of PUMA as a promising new substrate. A simple micro-device is developed and employed for observing the pressure deflection of membrane made from PUMA as a very effective elastomeric valve in microfluidic devices.

In the present paper the analysis of the leg movements of mechanical spider robot has been done. A mechanical spider is an eight leg robot which works on klann’s mechanism and can be used at bumpy roads, hilly area or any type of surfaces. Engineering specifications and requirements for the design of an artificial mechanism are the main objective of this paper.As fantastic as this idea may seem, recent developments in electroactive polymers (EAP) may one day make such bionics possible.As this technology continues to evolve, novel mechanisms that are biologically inspired are expected to emerge.In recognition of the need for cooperation in this multidisciplinary field, there is a series of international forums that are leading to a growing number of research and development projects and to great advances in the field. In this paper, the field of EAP as artificial muscles will be reviewed covering the state of the art, the challenges and the vision for the progress in future years.

In this study, grafted gelatin with oligoaniline (GelOA) was synthesized and then mixed with Poly (vinyl alcohol) (PVA). Several scaffolds with different ratio of PVA/GelOA were electrospun to fabricate electroactive scaffolds. GelOA was characterized using Fourier-transform infrared spectroscopy (FTIR); moreover, nanofiber properties were evaluated by differential scanning calorimetry (DSC), thermogravi-metric analysis (TGA), and scanning electron microscope (SEM) analyses. Nanofibers diameter was decreased with aniline oligomer increment form 300 to 150 nm because of the hydrophobic nature of the aniline oligomer. Aniline oligomer electroactivity was studied using cyclic voltammetry, which exhibited two redox peaks at 0.4 and 0.6. Moreover, aniline oligomer enhancement resulted in melting point increasing from 220°C to 230°C because of the crystallinity increment. To assess the biocompatibility of nanofibers, cell viability and cell adhesion were tracked using mesenchymal stem cell (MSCs). It was revealed that the presence of aniline oligomer leads to enhancing the conductivity, thermal properties and lowering the degradation rate and drug release. Among of different scaffolds, sample with high content of GelOA shows better behavior in physical and biological properties. Accumulative drug releases under

This paper describes experiments with the surface resistance of IPMC actuators and sensors. We measure the surface resistance of samples working as sensors or as a voltage driven actuators, as well as when insulated. The results show that in all cases the surface resistance of a sample is highly correlated to material curvature. Based on these observations we present an equivalent circuit, with variable resistors representing surface resistance, that models IPMC materials. Our simulations with SPICE show that the equivalent circuit closely models the actual behaviour of IPMC sensors and actuators. We show that since the IPMC model works as a delay line with changing resistors, the curvature of the IPMC sample at a given point depends on the surface resistance. This, in turn, affects further bending of the sample. The modified equivalent circuit also explains the hysteresis of IPMC actuators as the signals along the surface are delayed.

The classic movie Metropolis (1926), which is nowadays considered a cinema milestone, has shown the possibility to build robots called androids that are science and fiction run together to realize a dream: the human-like robot. In that movie, Dr. Rotwang transforms a simple and cold calculating robot into the body of a beautiful woman. Robots have often been depicted as metal creatures with cold steel bodies, but there is no reason why metals should be the only kind of material for construction of robots. The authors examined the issues related to applying electroactive polymers materials (EAP) to the entertainment industry. EAP are offering attractive characteristics with the potential to produce more realistic models of living creatures at significantly lower cost. This paper seeks to elucidate how EAP might infiltrate and ultimately revolutionize entertainment, showing some applicative examples.

When a high electric field is applied across a dielectric electro-active polymer, the stiffness, in the in-plane direction, decreases. This change in stiffness can be used to generate linear actuation in the out-of-plane direction if the dielectric electro-active polymer (DEAP) is subject to a suitable bias force. This bias force is commonly provided by a linear spring, but a recent research work suggests the use of so-called negative-rate bias springs (NBS) to increase the achievable stroke. These systems are geometrically non-linear systems with bi-stable mechanical characteristics with a negative stiffness between equilibrium points that can be efficiently matched to the DEAP load/deformation behavior.

This work contextualizes the research of materials that can be applied as artificial muscles. The main motivation of this research is the importance of the development of mechatronic systems for the replacement of traditional devices of actuation and motion based on rotational electrical motors by other devices that reproduce biological muscle movements. Electroactive polymers (EAPs) are materials that respond to electric stimuli with shape and/or dimension changes, and accomplish movements that are smooth enough to mimic biological muscles. Among EAPs, the ionomeric polymer-metal composites (IPMCs) are an interesting alternative to biomimetic devices due to large displacements when submitted to low applied voltage. This article presents a brief review of IPMCs, a sample preparation procedure, and some electromechanical experimental results. We also discuss the applicability of this technology in medical devices and as artificial muscles.

Dielectric elastomers are a class of electro-active polymers (EAPs) which have great potentials to be used in smart composites. These materials with compliant electrodes are converters of electrical energy to mechanical energy in order to produce external load and strain with good efficiency. Electrode materials should typically have good compliancy so that undergo large strain alongside the film, without producing any additional stress and constraint for the actuator. In the present study, the effect of 4 different electrode materials (graphite filled silicone oil, silver filled grease, graphite powder and electrically conductive silicone rubber) on the performance of dielectric elastomer actuators has been studied. The principle of operation, the method of fabrication and test method of planar actuators are discussed. We have also studied the effects of different driving voltages and different prestrain values on the actuator response. Experimental results showed that electrical conductivity, material compliancy, and compatibility with substrate in the electrode materials are some of the important parameters affecting the actuator performance.

The nonverbal expression of the emotions, especially in the human face, has rapidly become an area of intense interest in computer science and robotics. Exploring the emotions as a link between external events and behavioural responses, artificial intelligence designers and psychologists are approaching a theoretical understanding of foundational principles which will be key to the physical embodiment of artificial intelligence.

Ionic polymer-metal composites (IPMCs) are electroactive materials that bend under an applied electric field. Existing work has typically dealt with the control of IPMC actuators themselves. In this paper we investigate the stabilization of an inverted pendulum on a cart using an IPMC actuator. Different from the traditional setting of cart- pendulum systems, we require that the voltage on the IPMC actuator stay close to zero, to prolong the actuator life and reduce power consumption. A state-space model is developed for the system, based on which an LQR controller together with an observer is designed. The proposed control scheme is able to stabilize the inverted pendulum for the entire duration of the experiment (five minutes). These results indicate that IPMC actuators hold potential for more sophisticated control applications.

Myelination of Schwann cells (SCs) is critical for the success of peripheral nerve regeneration, and biomaterials that can promote SCs' neurotrophin secretion as scaffolds are beneficial for nerve repair. Here we present a biomaterials-approach, specifically, a highly tunable conductive biodegradable flexible polyurethane by polycondensation of poly(glycerol sebacate) and aniline pentamer, to significantly enhance SCs' myelin gene expression and neurotrophin secretion for peripheral nerve tissue engineering. SCs are cultured on these conductive polymer films, and the biocompatibility of these films and their ability to enhance myelin gene expressions and sustained neurotrophin secretion are successfully demonstrated. The mechanism of SCs' neurotrophin secretion on conductive films is demonstrated by investigating the relationship between intracellular Ca 2þ level and SCs' myelination. Furthermore, the neurite growth and elongation of PC12 cells are induced by adding the neurotrophin medium suspension produced from SCs-laden conductive films. These data suggest that these conductive degradable poly-urethanes that enhance SCs' myelin gene expressions and sustained neurotrophin secretion perform great potential for nerve regeneration applications.

This paper describes a novel self-sensing ion-conductive polymer metal composite (IPMC) actuator. The actuator gives feedback of its own position and thereby can also be used as a position sensor. Unlike the IPMC sensors reported so far, the working principle of this actuator is based on the observation that the resistance of the IPMC metal surface electrode is correlated to the bending curvature.

Novel combined chemical-electrochemical synthesis routes for the preparation of metal-free airoperated polypyrrole-based actuators are presented. The chemical synthesis phase provides the conductive electrode surface for the well-controllable electrochemical deposition of the working PPy material. Several new techniques not previously used in conducting polymer actuator preparation are described, including vapor-polymerization, oxidizer-painting and low temperature electrosynthesis in mixed aqueous solutions. Both commercially available and in-house membranes were used. The three described methods yielded well reproducible, functional actuators with acceptable displacement, strains and strain-rates. The most important characteristics of the actuators are presented.

Virtual Reality (VR) is gaining more importance in our society. For many years, VR has been limited to the entertainment applications. Today, practical applications such as training and prototyping find a promising future in VR. Therefore there is an increasing demand for low-cost, lightweight haptic devices in virtual reality (VR) environment. Electroactive polymers seem to be a potential actuation technology that could satisfy these requirements. Dielectric polymers developed the past few years have shown large displacements (more than 300%). This feature makes them quite interesting for integration in haptic devices due to their muscle-like behaviour. Polymer actuators are flexible and lightweight as compared to traditional actuators. Using stacks with several layers of elatomeric film increase the force without limiting the output displacement. The paper discusses some design methods for a linear dielectric polymer actuator for VR devices. Experimental results of the actuator performance is presented.

The Preisach operator and its variants have been successfully used in the modeling of hysteresis observed in ferromagnetic, magnetostrictive and piezoelectric materials. In an application involving these smart materials, one has to determine a density function for the Preisach operator using the inputoutput behavior of the material at hand. In this paper, we describe a method for numerically determining an approximation of the density function when there is not enough experimental data to uniquely solve for the density function. We present theoretical justification for our method by establishing links to regularization methods for ill-posed problems. We also present numerical results where we estimate an approximate density function from data published in the literature for a magnetostrictive actuator and two electro-active polymers.

The electrochemical investigation of the interaction between the anticancer drug mitomycin C (MC) and DNA was described using a single-walled carbon nanotube (SWCNT)/poly(vinylferrocenium) (PVF + ) modified pencil graphite electrode (PGE). The electrochemical oxidation signals of guanine were monitored before and after the interaction between MC and DNA by using differential pulse voltammetry. The effects of DNA and MC concentration and MC interaction time were examined based on the electrode response. Cyclic voltammetry and electrochemical impedance spectroscopy were used for the characterization of SWCNT/PVF + modified and PVF + modified PGEs. The detection limit corresponded to 625 ng/mL for MC using calf thymus double-stranded DNA immobilized SWCNT/PVF + modified PGE.

Thermoelectrochemical cells are a promising new technology for harvesting low-grade waste heat. The operation of these cells relies on a redox couple within an electrolyte, which is most commonly water-based, and improvement of these materials is a key aspect of the advancement of this technology. Here, we report the gelation of aqueous electrolytes containing the K 3 Fe(CN) 6 /K 4 Fe(CN) 6 redox couple using a range of different polymers, including polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (Cmc), polyacrylamide (PAAm), and two commercial polyurethane-based polymers: HydroMed D 640 and HydroSlip C. These polymers produce quasi-solid-state electrolytes with sufficient mechanical properties to prevent leakage, and allow improved device flexibility and safety. Furthermore, the incorporation of various ionic liquids within the optimized hydrogel network is investigated as a route to enhance the electrochemical and mechanical properties and thermal energy harvesting performance of the hydrogels.

For many years, EAPs received relatively little attention due to their limited actuation capability and the small number of available materials. In the last ten years, new EAP materials have emerged that exhibit large displacement response to electrical stimulation and they are enabling great potentials for the field. EAP are very attractive for their operational similarity to biological muscles, particularly their resilience, damage tolerant, and ability to induce large actuation strains. The application of these materials as actuators to drive various manipulation, mobility and robotic devices involves multidiscipline including materials, chemistry, electro-mechanics, computers, electronics, etc. Even though the force actuation of existing EAP materials and their robustness require further improvement, there has already been a series of reported successes. The successful devices that were reported include miniature manipulation devices including catheter steering element, miniature manipulator, dust-wiper, miniature robotic arm, grippers and others. Some of the currently considered applications may be difficult to accomplish and it is important to scope the requirements to the level that current materials can address. Using EAP to replace existing actuators may be a difficult challenge and therefore it is highly desirable to identify a niche application where it would not need to compete with existing capabilities. This paper will review the current efforts and the expectations for the future.

A novel method of fabrication of gadolinia doped bismuth oxide nanoceramic via the sol-gel technique is reported. Their thermal, structural and morphological properties are described by measurements of Differential Thermal Analysis/Thermal Gravimetry, X-ray Powder Diffraction and Scanning Electron Microscopy. The samples have stable high ion conductive face centered cubic δ-phase nanocrystalline structure. The electrical measurements of the nanoceramic powders were carried out in the temperature range of (689-1091 K) using 4-point probe technique. There is a transition between two distinct regions at 720 °C, which can be attributed to the order-disorder transition. This observation is supported by the differential thermal analysis measurements. The experimental results show that the value of conductivity increases with increasing temperature over linear parts characterized by two different activation energies. The conductivity data over whole measured temperature range were fitted the Arrhenius plot and it shows two linear regions with different slopes which correspond to low-temperature range (689-975 K) and high-temperature range (999- ersus q/kT plot as 1.25 eV and 2.81 eV for low-temperature range and high-temperature range, respectively.

The classic movie Metropolis (1926), which is nowadays considered a cinema milestone, has shown the possibility to build robots called androids that are science and fiction run together to realize a dream: the human-like robot. In that movie, Dr. Rotwang transforms a simple and cold calculating robot into the body of a beautiful woman. Robots have often been depicted as metal creatures with cold steel bodies, but there is no reason why metals should be the only kind of material for construction of robots. The authors examined the issues related to applying electroactive polymers materials (EAP) to the entertainment industry. EAP are offering attractive characteristics with the potential to produce more realistic models of living creatures at significantly lower cost. This paper seeks to elucidate how EAP might infiltrate and ultimately revolutionize entertainment, showing some applicative examples.

Ion-exchange polymer membrane metallic composites (IPMC) are one of the electroactive polymers (EAP) that were shown to have potential application as actuators. The recent introduction of perfluorocarboxylategold composite with tetra-n-butylammonium and lithium cations instead of sodium made the most significant improvement of the material's electroactivity. Under less than 3 volts, such IPMC materials were shown to induce bending beyond a complete loop. The bending characteristic of IPMC offered an attractive actuation capability for a dust wiper in planetary applications and it was explored for the Nanorover's infrared camera window of the MUSES-CN mission. This joint NASA and the Japanese space agency mission, is scheduled to be launched from Kagoshima, Japan, in January 2002, to explore the surface of a small near-Earth asteroid. The application of EAP at space conditions posed a great challenge due to the harsh operating conditions that are expected and the critical need for robustness and durability. Several issues that are critical to the application of IPMC were addressed including operation in vacuum and low temperatures, as well as the effect of the electromechanical characteristics of the IPMC on its actuation capability. Highly efficient IPMC materials, mechanical modeling, unique elements and protective coatings were introduced to enhance the applicability of this EAP material. However, critical issues were identified that hamper the transition of IPMC from being considered for practical applications at this stage.

a b s t r a c t A common usage for electroactive polymers (EAPs) is in different types of actuators, where advantage is taken of the deformation of the polymer due to an electric field. It turns out that time-dependent effects are present in these applications. One of these effects is the viscoelastic behavior of the polymer material. In view of the modeling and simulation of applications for EAP within a continuum mechanics setting, a phenomenological framework for an electro-viscoelastic material model is elaborated in this work. The different specific models are fitted to experimental data available in the literature. While the experimental data used for inherent electrostriction is restricted to small strains, a large strain setting is used for the model in order to account for possible applications where the polymers undergo large deformations, such as in pre-strained actuators.

Electroactive polymers (EAP) are attractive actuation materials because of their large deformation, flexibility, and lightweight. The large deformation, especially in the bending mode, poses a challenge to the material and actuator characterization due to the geometric nonlinearity that is involved with the characterization. A CCD camera system was constructed to record the curved shapes of bending during the activation of EAP films and image-processing software was developed to digitize the bending curves. A computer program was developed to solve the inverse problem of cantilever EAP beams with tip position limiter. Using the developed program and acquired curves with and without tip position limiter as well as the corresponding tip force, the EAP material properties of voltage-strain sensitivity and Young's modulus were determined. The experimental setup and the principles of the computer program that were developed are described and discussed in this paper.

A facile and low cost synthesis of Ni(OH)2 nanobelts (NBs) modified electroactive poly(vinylidene fluoride) (PVDF) thin films with excellent dielectric properties has been prepared via in situ formation of Ni(OH)2 NBs in PVDF matrix. Formation and
morphology of the NBs are confirmed by UV-Visible spectroscopy and Field emission scanning electron microscopy respectively. A remarkable improvement in electroactive β
phase nucleation (~82%) and dielectric constant (ε ~ 3.1 x 106 at 20 Hz) have been observed in the nanocomposites (NCs). The interface between the NBs and the polymer matrix plays a
crucial role in the enhancement of electroactive β phase and the dielectric properties of the thin films. Strong interaction via hydrogen bond between Ni(OH)2 NBs and PVDF matrix is
the main reason for enhancement β phase crystallization and improved dielectric properties.
The NC thin films can be utilized for potential applications as high energy storage devices like supercapacitors, solid electrolyte batteries, self-charging power cells, piezoelectric
nanogenerator, thin film transistors and sensors.

A simple ellipsometric technique is traditionally used for investigating the non-linear optical effects in poled polymer matrices. Upon writing a hologram in a low glass-transition-temperature photorefractive polymer composite, the chromophores are oriented in situ by the formed space-charge field. This way, the orientation of the chromophores gives us information about the latter one. We show how simple transmission ellipsometry can reproduce the results of the standard four-wave-mixing technique, yielding the quantitative determination of the space-charge field. Besides, this technique offers high sensitivity at low poling fields. This method is simple, easy-adjustable, and non-erasing, i.e. ideally suited to complement traditional holographic methods.

ABSTRACT Reconfigurable lens is biomimetic as it mimics human eye and is a transparent actuating material that can change its curvature in the presence of external stimuli. Focus tunable, adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, cost, efficiency and flexibility. To further improve the simplicity and compact nature of adaptive lenses, we present lens system which makes use of an inline, transparent electro active polymer actuator. This paper reports the preliminary development we have achieved in reconfigurable lens systems made with cellulose nanocrystals (CNC) using the principle of Kerr effect. Preparation of the hydrophobic CNC solution as well as the optical properties of the lens has been discussed. This soft gel actuator was analyzed by measuring the electric birefringence in the pulse field of constant and sinusoidal voltage based on the use of modulation of elliptic light polarization.

Besides the scale factor that distinguishes the various spices fundamentally biological muscles changes little between species indicating a highly optimized system, Electroactive polymer actuators offer the closest resemblance to biological muscles however beside the large actuation displacement these materials are falling short with regards to the actuation force. As improved materials emerging it is becoming necessary to address key issues such as the need for effective electromechanical modeling and guiding parameters in scaling the actuators. In this paper, we will review the scaling laws for three major actuation mechanisms that are of relevance to micro electromechanical systems: electrostatic actuation, magnetic actuation, thermal bimetallic actuation, and piezoelectric actuation.

Dielectric elastomers are a class of electro-active polymers (EAPs) which have been used for smart structures, such as muscle-like actuators. These materials with compliant electrodes are transducers of electrical to mechanical energy, with extremely large strain and good efficiency. A thorough understanding of the physics underlying the nature of different electrode materials can help modify actuator response. The objective of this paper is to investigate the effect of 4 different electrodes (graphite powder, carbon filled grease, silver filled grease and electrically conductive silicone rubber) on the performance of dielectric elastomer actuators. The principle of operation, the method of fabrication and test method of planar actuators are discussed. Effects of different driving voltages and different prestrain values on the actuator response have been studied. Electrical conductivity under strain, electrode surface uniformity and mechanical compatibility with substrate, as the mo...

In order to make EAP actuators technology scalable a design methodology for polymer actuators is required. Design variables, optimization formulas and a general architecture are required as it is usual in electromagnetic or hydraulic actuators design. This will allow the development of large EAP actuators from micro-actuator units, specifically designed for a particular application. It will also help to enhance the EAP material final performance. This approach is not new, since it is found in Nature. Skeletal muscle architecture has a profound influence on muscle force-generating properties and functionality. Based on existing literature on skeletal muscle biomechanics, the Nature design philosophy is inferred. Formulas and curves employed by Nature in the design of muscles are presented. Design units such as fiber, tendon, aponeurosis, and motor units are compared with the equivalent design units to be taken into account in the design of EAP actuators. Finally a complete design methodology for the design of actuators based on multiple EAP fiber/sheets is proposed. In addition, the procedure gives an idea of the required parameters that must be clearly modeled and characterized at EAP material level prior to attempt the design of complex Electromechanical Systems based on Electroactive Polymers.

When a high electric field is applied across a dielectric electro-active polymer, the stiffness, in the in-plane direction, decreases. This change in stiffness can be used to generate linear actuation in the out-of-plane direction if the dielectric electro-active polymer (DEAP) is subject to a suitable bias force. This bias force is commonly provided by a linear spring, but a recent research work suggests the use of so-called negative-rate bias springs (NBS) to increase the achievable stroke. These systems are geometrically non-linear systems with bi-stable mechanical characteristics with a negative stiffness between equilibrium points that can be efficiently matched to the DEAP load/deformation behavior.

This study is related to the preparation of boron doped Nickel/Zinc metal fibers prepared by the use of electrospinning technique. The originality of this study is the addition of boron to metal acetates. The addition of boron did not only increase the thermal stability of the fibers, but also increased their diameters, which gave stronger fibers. The FT-IR spectra of the fibers were in good accordance with literature. The differential scanning calorimetry (DSC) results indicate that the glass transition (T g ) and melting temperatures (T m ) showed great change with the addition of boron and boron doped fibers were observed to degrade at higher temperatures. The SEM appearance of the fibers showed that the addition of boron resulted in the formation of cross linked bright surfaced fibers.

The electrochemical oxidation of para-, meta-and ortho-aminophenols was carried out using a platinum electrode in aqueous acid medium. The spectroscopic results indicate that p-aminophenol suffers hydrolysis giving the formation of hydroquinone/pbenzoquinone. CO 2 has been detected by in situ FTIR spectroscopy as the main soluble oxidation product. The m-aminophenol oxidation produces a blocking polymeric film on the platinum surface. The main oxidation products detected by in situ infrared spectroscopy were CO 2 and quinone. Cyclic voltammetry and in situ FTIR spectroscopy were combined to study the redox processes of the conducting polymer obtained in the o-aminophenol oxidation. The spectroscopic results indicate that phenoxazine units are produced during the oxidation/reduction of poly(o-aminophenol).

Transducing materials are being used in many aspects of our daily life serving as actuators, sensors, displays, communications and other components of commercial mechanisms. At JPL, such materials are being used to enable novel space and terrestrial applications. This effort involves mostly the use of piezoelectric, electroactive polymers (EAP), and shape memory alloys (SMA). The piezoelectric based devices and mechanisms that were developed include ultrasonic motors, piezopump, ultrasonic/sonic driller/corer (USDC), whereas the electroactive polymers were used to demonstrate a gripper, wiper, lifter and haptic interfaces. The research involves analytical modeling, experimental corroboration, material characterization and device/mechanism design, construction and demonstration. The effort is multidisciplinary requiring expertise that is complemented through international cooperation. The research team activity will be reviewed in this paper.

Electroactive polymers (EAP) are an emerging class of actuation materials. Their large electrically induced strains (longitudinal or bending), low density, mechanical flexibility, and ease of processing offer advantages over traditional electroactive materials. However, before the benefits of these materials can be exploited, their electrical and mechanical behavior must be properly quantified. Two general types of EAP can be identified. The first class is ionic EAP, which requires relatively low voltages (<10V) to achieve large bending deflections. This class usually needs to be hydrated and electrochemical reactions may occur. The second class is Electronic-EAP and it involves piezoelectric, electrostrictive and/or Maxwell stresses. These materials can require large electric fields (>100MV/m) to achieve longitudinal deformations at the range from 4 -360%. Some of the difficulties in characterizing EAP include: nonlinear properties, large compliance (large mismatch with metal electrodes), nonhomogeneity (resulting from processing) and hysteresis. To support the need for reliable data, the authors are developing characterization techniques to quantify the electroactive responses and material properties of EAP materials. The emphasis of the current study is on addressing electromechanical issues related to the ion-exchange type EAP also known as IPMC. The analysis, experiments and test results are discussed in this paper.

NASA is seeking to reduce the mass, size, consumed power, and cost of the instrumentation used in its future missions. An important element of many instruments and devices is the actuation mechanism and electroactive polymers offer an effective alternative to current actuators. In this study, two families of electroactive polymer materials were investigated, including bending ionomers and longitudinal electrostatically driven elastomers. These materials were demonstrated to effectively actuate manipulation devices and their performance is being enhanced in this on-going study. The recent observations are reported in this paper, which also include cryovac tests at conditions that simulate Mars environment. Tests at T equals -140 degree(s)C and P approximately 1 Torr, which are below Mars conditions, showed that the bending actuator was still responding with a measurable actuation displacement. Analysis of the electrical characteristics of the ionomer showed that it is a current driven material rather than voltage driven. Measurements of transient currents in response to a voltage step shows a time constant on the order of few seconds with a response speed that is enhanced with the decrease in drive voltage. The ionomer main limitation is its requirement for being continuously moist. Tests showed that while the performance degrades as the material becomes dry, its AC impedance increases, reaching an order of magnitude higher than the wet ionomer. This response provides a gauging indication of the material wetness status. Methods of forming the equivalent of a skin to protect the moisture content of the ionomer are being sought and a limited success was observed using thick platinum electroding as well as when using polymeric coating.

Methacrylic-based thermo-set gel-polymer electrolytes obtained by an easy and reliable free radical photo-polymerisation process demonstrate good behaviour in terms of ionic conductivity, interfacial stability with the Li-metal electrode and cyclability in lithium cells. Though the obtained membranes are flexible, self standing and easy to handle, there is room for improving mechanical strength. In this respect, a novel approach is adopted in this work, in which a cellulose hand-sheet (paper), specifically designed for the specific application, is used as a composite reinforcing agent. To enhance its compatibility with the polymer matrix, cellulose is modified by UV-grafting of poly(ethylene glycol) methyl ether methacrylate on it. Excellent mechanical properties are obtained and good overall electrochemical performances are maintained; highlighting that such specific approach would make these hybrid organic, green, cellulosebased composite polymer electrolyte systems a strong contender in the field of thin and flexible Li-based power sources.

Conductometric transducing is suggested for electrocatalytic chemical sensors based on conductive polymers. Lateral conductivity of the polymer layers was measured by two-and four-point techniques. The approach was applied for electroanalytical detection of ascorbic acid on the electrocatalytically active polyaniline and poly-ortho-methoxyaniline electrodes. Both polymers displayed a monotonous concentration dependence of their conductance in the analytically important sub-millimolar concentration range of ascorbic acid. The approach was tested in model solutions of ascorbic acid in buffer and applied for detection of ascorbic acid in orange juice.

Muscles fulfill several functions within an animal's body. During locomotion they propel and control the limbs in unstructured environments. Therefore, the functional workspace of muscle needs to be represented by variables describing energy management (i.e. power output, efficiency) as well as control aspects (i.e. stiffness, damping). Muscles in the animal kingdom vary greatly with respect to those variables. To study if ElectroActive Polymer's (EAP) can be considered as artificial muscles we are making a direct comparison between the contractile properties of EAP's and biological muscle. We have measured the functional workspace of EAP actuators using the same setup and techniques that we use to test biological muscle. We evaluated the properties of three different EAP materials; the acrylic and silicone dielectric elastomers developed at 'SRI International' and the high-energy electron-irradiated co-polymers (P(VDF-TrFE)) developed at the MRL laboratory at Penn State University. Initial results indicate that the EAP materials partly capture the functional workspace of natural muscle and sometimes even exceed the capabilities of muscle. Based on the data we have collected it seems that both EAP technologies have characteristics that could qualify them as artificial muscles.