Development of a biomechanical energy harvester

© 2009 Li et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Dielectric elastomers as electromechanical transducers - Fundamentals, materials, devices, models & applications of an emerging electroactive polymer technology

This book describes one of the most promising classes of polymer-based smart materials and technologies for electromechanical transducers and "pseudo-muscular" actuation devices to be used in a very broad range of applications, spanning from robotics and automation to the biomedical field. This class of materials, known as "dielectric elastomers", belong to the larger family of so-called ElectroActive Polymers (EAP), currently being developed and studied as "artificial muscles". Dielectric elastomer actuation is drawing a particular interest because of its promise of simple and robust low-cost devices with overall performance exceeding most conventional technologies, such as electromagnetics and piezoelectrics. In fact, dielectric elastomer actuators have demonstrated strain and energy density exceeding that of all high-speed field-activated actuation technologies. Further, in addition to actuation, dielectric elastomers have also been shown to offer unique possibilities for improved generator and sensing devices. Dielectric elastomer transduction was introduced during the 1990s, pioneered by SRI International. Although the field is still being explored and expanded extensively, a great deal of work has already been done, with encouraging results. This technology is enabling today an enormous range of applications that were not possible with any other EAP or smart-material technology until a few years ago. For interested readers, this book is expected to provide a comprehensive and updated insight on this technology. The book covers all the fundamental aspects, comprising a collection of chapters written by the fathers of this technology, along with the most renowned international contributors in the field. The presented topics range from transduction principles, basic materials properties, design of devices, material and device modelling, up to possible applications and future research avenues. Such an extension of the covered topics is expected to make this text as the first reference handbook on dielectric elastomer transduction. Book jacket. © 2008 Elsevier Ltd All rights reserved

Myelin oligodendrocyte glycoprotein antibody-associated disease as a novel presentation of central nervous system autoimmunity in a pediatric patient with Wiskott-Aldrich syndrome

Abstract Background Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency caused by mutations in the WAS gene that leads to increased susceptibility to infections, thrombocytopenia, eczema, malignancies, and autoimmunity. Central nervous system (CNS) autoimmune manifestations are uncommon. Case Presentation We describe the case of a five-year-old boy with refractory thrombocytopenia and iron deficiency anemia who developed relapsing bilateral optic neuritis. Myelin oligodendrocyte glycoprotein antibody (MOG-IgG) via serum fluorescence-activated cell sorting assay was positive (titer 1:100), confirming a diagnosis of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). At age six, molecular panel testing for genes associated with primary immunodeficiency identified a missense WAS gene variant. He was subsequently found to have decreased WAS protein expression, consistent with a diagnosis of WAS. Conclusions This case expands the reported spectrum of CNS autoimmunity associated with WAS and may help to inform long-term therapeutic options

Capacitive energy harvesting using soft dielectric elastomers: Design, testing and impedance matching optimization

Energy harvesting based on dielectric elastomeric materials, in nature, embodies a capacitive kinetic energy conversion mechanism where the soft DE generator (DEG) interactively cooperates with conditioning circuits. Based on the principle of passive charge pump, this paper proposes a design concept for a self-cycling energy harvesting circuit driven by DEG cyclic deformation, with its essential behavioral mode laid on the electrical reciprocity between the DEG intrinsic capacitor and another capacitor connected in series. By detailed simulation experiments, the working process and dynamic characteristics of the proposed system, as well as the influence of circuital, operating, and load parameters on system performance are quantitatively investigated, with intensive discussions for the time delay behaviors caused by changes of load resistance, along with the different impacts of its value regions. Then, the theoretical analyses are effectively validated by experimental tests for a specially-designed annular DEG prototype. Under the global optimization framework based on impedance matching, this paper presents some guidelines for circuit design, e.g., the selection criteria of the capacitance and load resistance. In addition, the potential of this emerging technology is also demonstrated by experiments