|Author||: Federico Carpi,Danilo De Rossi,Roy Kornbluh,Ronald Edward Pelrine,Peter Sommer-Larsen|
|Release Date||: 2011-09-06|
|ISBN 10||: 9780080557724|
|Pages||: 344 pages|
Dielectric Elastomers as Electromechanical Transducers provides a comprehensive and updated insight into dielectric elastomers; one of the most promising classes of polymer-based smart materials and technologies. This technology can be used in a very broad range of applications, from robotics and automation to the biomedical field. The need for improved transducer performance has resulted in considerable efforts towards the development of devices relying on materials with intrinsic transduction properties. These materials, often termed as “smart or “intelligent , include improved piezoelectrics and magnetostrictive or shape-memory materials. Emerging electromechanical transduction technologies, based on so-called ElectroActive Polymers (EAP), have gained considerable attention. EAP offer the potential for performance exceeding other smart materials, while retaining the cost and versatility inherent to polymer materials. Within the EAP family, “dielectric elastomers , are of particular interest as they show good overall performance, simplicity of structure and robustness. Dielectric elastomer transducers are rapidly emerging as high-performance “pseudo-muscular actuators, useful for different kinds of tasks. Further, in addition to actuation, dielectric elastomers have also been shown to offer unique possibilities for improved generator and sensing devices. Dielectric elastomer transduction is enabling an enormous range of new applications that were precluded to any other EAP or smart-material technology until recently. This book provides a comprehensive and updated insight into dielectric elastomer transduction, covering all its fundamental aspects. The book deals with transduction principles, basic materials properties, design of efficient device architectures, material and device modelling, along with applications. Concise and comprehensive treatment for practitioners and academics Guides the reader through the latest developments in electroactive-polymer-based technology Designed for ease of use with sections on fundamentals, materials, devices, models and applications
|Author||: Jianyou Zhou|
|Release Date||: 2015|
|Pages||: 278 pages|
Dielectric elastomer transducers with large deformation, high energy output, light weight and low cost have been drawing great interest from both the research and industry communities, and shown potential for versatile applications in biomimetics, dynamics, robotics and energy harvesting. However, in addition to multiple failure modes such as electrical breakdown, electromechanical instability, loss-of- tension and fatigue, the performance of dielectric elastomer transducers are also strongly influenced by the hyperelastic and viscoelastic properties of the material. Also, the interplay among these material properties and the failure modes is rather difficult to predict. Therefore, in order to provide guidelines for the optimal design of dielectric elastomer transducers, it is essential to first develop accurate and reliable models, and efficient numerical methods to investigate their performance. First, this thesis purposes a boundary- constraint method to eliminate the electromechanical instability of dielectric elastomer actuators under voltage-control loading condition and improve their actuation deformation. Second, based on the finite-deformation viscoelasticity model, the natural frequency tuning process of viscoelastic dielectric elastomer resonators is examined in this work. It is found that the tuned natural frequency is highly affected by the material viscoelasticity. Also, it is concluded that the electrical loading rate only influences the tunable frequency range and the safe operation voltage of the resonator, but not the tuned natural frequency when the applied voltage is within the safe range. Third, with the finite-deformation viscoelasticity model, the energy conversion efficiency of dielectric elastomer generators under equi-biaxial loading is also investigated in this work. Simulation results show that increasing the maximum stretch ratio and the rate of defor mation, and choosing a proper bias voltage can lead to an improvement of the energy conversion efficiency. Furthermore, the fatigue life of dielectric elastomer devices under cyclic loading is explored in this work for the first time . Simulation results have demonstrated that the energy conversion efficiency of dielectric elastomer generators is compromised by their fatigue life. To tackle the critical challenges for the development and design of dielectric elastomers transducers, this research develops theoretical models and numerical methods that are able to capture the nonlinear electromechanical coupling, the material properties, the typical failure modes and different operating conditions of dielectric elastomer transducers. With more accurate and reliable modeling methods, this work is expected to provide a comprehensive understanding on the fundamentals and technologies of dielectric elastomer transducers and trigger more innovative and optimal design of such devices.
Electroactivity in Polymeric Materials provides an in-depth view of the theory of electroactivity and explores exactly how and why various electroactive phenomena occur. The book explains the theory behind electroactive bending (including ion-polymer-metal-composites –IPMCs), dielectric elastomers, electroactive contraction, and electroactive contraction-expansion cycles. The book also balances theory with applications – how electroactivity can be used – drawing inspiration from the manmade mechanical world and the natural world around us.
Advances in Energy Harvesting Methods presents a state-of-the-art understanding of diverse aspects of energy harvesting with a focus on: broadband energy conversion, new concepts in electronic circuits, and novel materials. This book covers recent advances in energy harvesting using different transduction mechanisms; these include methods of performance enhancement using nonlinear effects, non-harmonic forms of excitation and non-resonant energy harvesting, fluidic energy harvesting, and advances in both low-power electronics as well as material science. The contributors include a brief literature review of prior research with each chapter for further reference.
Smart mobile systems like micro-systems, smart textiles and implants and sensor-controlled medical devices, together with related networks and cloud services, are important enablers for telemedicine and pervasive health to become the next generation of health services. Social media and gamification have added further to pHealth as an ecosystem. This book presents the proceedings of pHealth 2019, the 16th in a series of international conferences on personalized health, held in Genoa, Italy, from 10 – 12 June 2019. The book includes 1 keynote, 2 of 4 invited talks, 36 oral presentations and 7 poster presentations from a total of 141 international authors. All submissions were critically reviewed by at least two independent experts and a member of the Scientific Program Committee. This process resulted in a full paper rejection rate of more than 30%. Besides wearable or implantable micro and nano technologies for personalized medicine, this volume addresses topics such as legal, ethical, social, and organizational requirements and impacts as well as necessary basic research for enabling future proof care paradigms. Such participatory, predictive, personalized, preventive, and effective care settings combine medical services and public health, prevention, social and elderly care, but also wellness and personal fitness. The multilateral benefits of pHealth technologies for all stakeholder communities offer enormous potential for the improvement of both care quality and industrial competitiveness, and also for the management of health care costs. Hence, the book will be of interest to all those involved in the provision of healthcare.
Contemporary research in the field of robotics attempts to harness the versatility and sustainability of living organisms. By exploiting those natural principles, scientists hope to render a renewable, adaptable, and robust class of technology that can facilitate self-repairing, social, and moral—even conscious—machines. This is the realm of robotics that scientists call "the living machine". Living Machines can be divided into two entities-biomimetic systems, those that harness the principles discovered in nature and embody them in new artifacts, and biohybrid systems, which couple biological entities with synthetic ones. Living Machines: A handbook of research in biomimetic and biohybrid systems surveys this flourishing area of research. It captures the current state of play and points to the opportunities ahead, addressing such fields as self-organization and co-operativity, biologically-inspired active materials, self-assembly and self-repair, learning, memory, control architectures and self-regulation, locomotion in air, on land or in water, perception, cognition, control, and communication. In all of these areas, the potential of biomimetics is shown through the construction of a wide range of different biomimetic devices and animal-like robots. Biohybrid systems is a relatively new field, with exciting and largely unknown potential, but one that is likely to shape the future of humanity. Chapters outline current research in areas including brain-machine interfaces-where neurons are connected to microscopic sensors and actuators-and various forms of intelligent prostheses from sensory devices like artificial retinas, to life-like artificial limbs, brain implants, and virtual reality-based rehabilitation approaches. The handbook concludes by exploring the impact living machine technology will have on both society and the individual, by forcing human beings to question how we see and understand ourselves. With contributions from leading researchers drawing on ideas from science, engineering, and the humanities, this handbook will appeal to both undergraduate and postgraduate students of biomimetic and biohybrid technologies. Researchers in the areas of computational modeling and engineering, including artificial intelligence, machine learning, artificial life, biorobotics, neurorobotics, and human-machine interfaces, will find Living Machines an invaluable resource.
|Author||: David McCoul|
|Release Date||: 2015|
|Pages||: 379 pages|
Dielectric elastomers have demonstrated tremendous potential as high-strain electromechanical transducers for a myriad of novel applications across all engineering disciplines. Because their soft, viscoelastic mechanical properties are similar to those of living tissues, dielectric elastomers have garnered a strong foothold in a plethora of biomedical and biomimetic applications. Dielectric elastomers consist of a sheet of stretched rubber, or elastomer, coated on both sides with compliant electrode materials; application of a voltage generates an electrostatic pressure that deforms the elastomer. They can function as soft generators, sensors, or actuators, and this last function is the focus of this dissertation. Many design configurations are possible, such as stacks, minimum energy structures, interpenetrating polymer networks, shape memory dielectric elastomers, and others; dielectric elastomers are already being applied to many fields of biomedicine. The first part of the original research presented in this dissertation details a PDMS microfluidic system paired with a dielectric elastomer stack actuator of anisotropically prestrained VHB(TM) 4910 (3M(TM)) and single-walled carbon nanotubes. These electroactive microfluidic devices demonstrated active increases in microchannel width when 3 and 4 kV were applied. Fluorescence microscopy also indicated an accompanying increase in channel depth with actuation. The cross-sectional area strains at 3 and 4 kV were approximately 2.9% and 7.4%, respectively. The device was then interfaced with a syringe pump, and the pressure was measured upstream. Linear pressure-flow plots were developed, which showed decreasing fluidic resistance with actuation, from 0.192 psi/(microL/min) at 0 kV, to 0.160 and 0.157 psi/(microL/min) at 3 and 4 kV, respectively. This corresponds to an ~18% drop in fluidic resistance at 4 kV. Active de-clogging was tested in situ with the device by introducing ~50 m diameter PDMS microbeads and other smaller particulate debris into the system. After a channel blockage was confirmed, three actuation attempts successfully cleared the blockage. Further tests indicated that the device were biocompatible with HeLa cells at 3 kV. To our knowledge this is the first pairing of dielectric elastomers with microfluidics in a non-electroosmotic context. Applications may include adaptive microfilters, micro-peristaltic pumps, and reduced-complexity lab-on-a-chip devices. Dielectric elastomers can also be adapted to manipulate fluidic systems on a larger scale. The second part of the dissertation research reports a novel low-profile, biomimetic dielectric elastomer tubular actuator capable of actively controlling hydraulic flow. The tubular actuator has been established as a reliable tunable valve, pinching a secondary silicone tube completely shut in the absence of a fluidic pressure bias or voltage, offering a high degree of resistance against fluidic flow, and able to open and completely remove this resistance to flow with an applied low power actuation voltage. The system demonstrates a rise in pressure of ~3.0 kPa when the dielectric elastomer valve is in the passive, unactuated state, and there is a quadratic fall in this pressure with increasing actuation voltage, until ~0 kPa is reached at 2.4 kV. The device is reliable for at least 2,000 actuation cycles for voltages at or below 2.2 kV. Furthermore, modeling of the actuator and fluidic system yields results consistent with the observed experimental dependence of intrasystem pressure on input flow rate, actuator prestretch, and actuation voltage. To our knowledge, this is the first actuator of its type that can control fluid flow by directly actuating the walls of a tube. Potential applications may include an implantable artificial sphincter, part of a peristaltic pump, or a computerized valve for fluidic or pneumatic control. The final part of the dissertation presents a novel dielectric elastomer band with integrated rigid elements for the treatment of chronic acid reflux disorders. This dielectric elastomer ring actuator consists of a two-layer stack of prestretched VHB(TM) 4905 with SWCNT electrodes. Its transverse prestretch was maintained by selective rigidification of the VHB(TM) using a UV-curable, solution-processable polymer network. The actuator exhibited a maximum vertical (circumferential) actuation strain of 25% at 3.4 kV in an 24.5 g weighted isotonic setup. It also exhibited the required passive force of 0.25 N and showed a maximum force drop of 0.11 N at 3.32 kV during isometric tests at 4.5 cm. Modeling was performed to determine the prestretches necessary to achieve maximum strain while simultaneously exerting the force of 0.25 N, which corresponds to a required pinching pressure of 3.35 kPa. Modeling also determined the spacing between and number of rigid elements required. The theoretical model curves were adjusted to account for the passive rigid elements, as well as for the addition of margins; the resulting plots agrees well with experiment. The performance of the DE band is comparable to that of living muscle, and this is the first application of dielectric elastomer actuators in the design of a medical implant for the treatment of gastrointestinal disorders. Related applications that could result from this technology are very low-profile linear peristaltic pumps, artificial intestines, an artificial urethra, and artificial blood vessels.
|Release Date||: 2018|
|Pages||: 329 pages|
Abstract: Self-sensing enables electromechanical transducers of being simultaneously used for actuating and sensing without additional, external sensors. In case of dielectric elastomer (DE) transducers the shape-varying, strain-dependent capacitance is usually considered for this purpose and estimated based on the measured terminal voltage and current. In the literature most self-sensing algorithms for DE transducers require an explicit superimposition of an additional AC excitation signal. Thus, only power supplies providing the opportunity of superimposing this excitation signal can be used for this purpose. Within this contribution we propose a new approach based on an extended Kalman filter. It operates with any arbitrary driving signal and thus does not require a superimposed excitation. Here, the extended Kalman filter is used for both the estimation of the inner states and parameters of the nonlinear process. The accuracy and dynamics of the estimation results obtained with proposed self-sensing approach are demonstrated by comparing the estimated with the measured transducer strain. The measurements are conducted with two different power supplies showing the applicability and robustness of the proposed self-sensing approach ensuring reliable and accurate estimation results independent of the kind of excitation signal. Here, the utilized high voltage amplifier represents a common power supply for experimental studies in laboratory environment. In contrast, the bidirectional flyback-converter is an energy-efficient and economical opportunity for feeding of DE transducers in technologically sophisticated applications. However, due to its operation principle it does not provide the opportunity to superimpose particular sensing signals so that this new approach is required to enable the self-sensing capability.
This book covers the fundamental properties, modeling, and demonstration of Electroactive polymers in robotic applications. It particularly details artificial muscles and sensors. In addition, the book discusses the properties and uses in robotics applications of ionic polymer–metal composite actuators and dielectric elastomers.
|Author||: Yoseph Bar-Cohen|
|Publisher||: SPIE Press|
|Release Date||: 2004-01-01|
|ISBN 10||: 9780819452979|
|Pages||: 765 pages|
In concept and execution, this book covers the field of EAP with careful attention to all its key aspects and full infrastructure, including the available materials, analytical models, processing techniques, and characterization methods. In this second edition the reader is brought current on promising advances in EAP that have occurred in electric EAP, electroactive polymer gels, ionomeric polymer-metal composites, carbon nanotube actuators, and more. 'Electroactive Polymer (EAP) Actuators as Artificial Muscles' is a delightful book dealing with one of the hottest topics in biomedical engineering. Virtually every known method of generating displacement is introduced. This book is a must for anyone interested in actuators and sensors, including physicians and biomedical, chemical, electrical, and material engineers. It is thorough in every way.... --Steven S. Saliterman, MD, FACP, Chief of Medicine Methodist Hospital; Department of Biomedical Engineering, University of Minnesota