A5082345097- Advanced Sensor and Energy Harvesting Materials
- Dielectric materials and actuators
- Ferroelectric and Piezoelectric Materials
- Advanced Materials and Mechanics
- Innovative Energy Harvesting Technologies
- Advanced MEMS and NEMS Technologies
- Vibration Control and Rheological Fluids
- Prosthetics and Rehabilitation Robotics
- Modular Robots and Swarm Intelligence
- Adhesion, Friction, and Surface Interactions
- Conducting polymers and applications
- Electrowetting and Microfluidic Technologies
- Biomimetic flight and propulsion mechanisms
- Soft Robotics and Applications
- Tactile and Sensory Interactions
- Structural Engineering and Vibration Analysis
- Silicone and Siloxane Chemistry
- Hybrid Renewable Energy Systems
- Additive Manufacturing and 3D Printing Technologies
- Smart Materials for Construction
- Aerospace Engineering and Energy Systems
- Aerospace Engineering and Control Systems
- Mechanical and Optical Resonators
- Rocket and propulsion systems research
- Guidance and Control Systems
SRI International
2010-2023
Menlo School
2002-2023
SRA International (United States)
2008
University of California, San Diego
2008
Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed film in thickness and expanded it area, producing strains up to 30 40%. It is now shown that prestraining further improves performance these devices. Actuated 117% demonstrated silicone elastomers, 215% acrylic using biaxially uniaxially prestrained films. The strain, pressure,...
Polyacrylate dielectric elastomers have yielded extremely large strain and elastic energy density suggesting that they are useful for many actuator applications. A thorough understanding of the physics underlying mechanism observed response to an electric field can help develop improved actuators. The is believed be due Maxwell stress, a quadratic dependence stress upon applied field. Based on this supposition, equation relating voltage measured force from was derived. Experimental data fit...
Dielectric elastomers have shown great promise as actuator materials. Their advantages in converting mechanical to electrical energy a generator mode are less well known. If low voltage charge is placed on stretched elastomer prior contraction, the contraction works against electrostatic field pressure and raises of charge, thus generating energy. This paper discusses fundamentals dielectric generators, experimental verification phenomenon, practical issues, potential applications. Acrylic...
A flexible and lightweight device uses an electrocaloric polymer film to provide exceptional cooling power.
Making small robots stick Aerial views offer the chance to observe a wide range of terrain at once, but they come cost needing stay aloft. Graule et al. found that electrostatic forces could keep their insect-sized flying robot stuck underside surfaces (see Perspective by Kovac). They mounted an electrostatically charged pad top robot, which then reversibly existing elevated perches—including leaf—using less power than would be needed for sustained flight. Science , this issue p. 978 ; see also 895
Dielectric elastomer transducers consist of thin electrically insulating elastomeric membranes coated on both sides with compliant electrodes. They are a promising electromechanically active polymer technology that may be used for actuators, strain sensors, and electrical generators harvest mechanical energy. The rapid development this field calls the first standards, collecting guidelines how to assess compare performance materials devices. This paper addresses need, presenting standardized...
Dielectric elastomers are a new class of actuator materials that exhibit excellent performance. The principle operation, as well methods to fabricate and test these elastomers, is summarized here. Figure sketch an elastomer film (light gray) stretched on frame (black) patterned with electrode (mid-gray). Upon applying voltage, the active portion expands strain can easily be measured optically.
Electroactive polymers (EAPs) can overcome many limitations of traditional smart material and transducer technologies. A particularly promising class EAP is dielectric elastomer, also known as electroelastomer. Dielectric elastomer transducers are rubbery polymer materials with compliant electrodes that have a large electromechanical response to an applied electric field. The technology has been developed the point where exceptional performance already demonstrated: for example, actuated...
This paper describes a novel clamping technology called compliant electroadhesion, as well the first application of this to wall climbing robots. As name implies, electroadhesion is an electrically controllable adhesion technology. It involves inducing electrostatic charges on substrate using power supply connected pads situated moving robot. High forces (0.2-1.4 Newton supported by 1 square centimeter clamp area, depending substrate) have been demonstrated wide variety common building...
To achieve desirable biomimetic motion, actuators must be able to reproduce the important features of natural muscle such as power, stress, strain, speed response, efficiency, and controllability. It is a mistake, however, consider only an energy output device. Muscle multifunctional. In locomotion, often acts absorber, variable-stiffness suspension element, or position sensor, for example. Electroactive polymer technologies based on electric-field-induced deformation dielectrics with...
The type of electroactive polymer known as dielectric elastomers has shown considerable promise for a variety actuator applications and may be well suited harvesting energy from environmental sources such ocean waves or water currents. high density conversion efficiency can allow very simple robust "direct drive" generators. Preliminary generators based on have been tested. A generator attached to rotating waterwheel via crankshaft produced 35 mJ per revolution in laboratory test with an...
Dielectric elastomers offer the promise of energy harvesting with few moving parts. Power can be produced simply by stretching and contracting a relatively low-cost rubbery material. This simplicity, combined demonstrated high density efficiency, suggests that dielectric are promising for wide range applications. Indeed, have been to harvest from human walking, ocean waves, flowing water, blowing wind, pushing buttons. While technology is promising, there challenges must addressed if...
Extremely large strains were achieved with elastomeric polymer films that are subject to high electric fields. The coated on both sides complaint electrode material. When voltage was applied, the film compressed in thickness and expanded area. strain response is dominated by electrostatic forces produced charges compliant electrodes. Actuated up 117% demonstrated silicone elastomers, 215% acrylic elastomers. A key achieving these introduce a prestrain film. Specific energy densities much...
Many new robotic and teleoperated applications require a high degree of mobility or dexterity that is difficult to achieve with current actuator technology. Natural muscle an has many features, including energy density, fast speed response, large stroke, are desirable for such applications. The electrostriction polymer dielectrics compliant electrodes can be used in electrically controllable, muscle-like actuators. These electrostrictive artificial (EPAM) actuators produce strains up 30%...
Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined fast response time and high electromechanical efficiency. This unique performance, other factors such as low cost, suggests many potential applications, wide range which are under investigation. Applications that effectively exploit properties dielectric elastomers include artificial muscle actuators for robots; low-cost,...
In 1997 the Defense Advanced Research Projects Agency initiated a program to explore possibility of micro air vehicles for purpose individually portable surveillance systems close-range operations. The various contractors approached problem in several ways, such as developing tiny fixed-wing airplanes, rotary-wing aircraft, and ornithopters mimicking animal flight This paper describes one flapping-wing which drew upon clap-fling phenomenon that is exploited by many flying animals insects...
A new type of loudspeaker that generates sound by means the electrostrictive response a thin polymer film is described. Electrostrictive (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have very low profile. The films typically silicone coated compliant electrodes to allow large deformations. Acoustical frequency measurements from 5×5 cm (planar dimensions) prototype EPF presented. Measurements harmonic distortion also shown, along results demonstrating reduced...
Electroelastomers (also called dielectric elastomer artificial muscles) have been shown to exhibit excellent performance in a variety of actuator configurations, but making compact, free-standing, muscle-like capable obtaining good has challenge. By rolling highly prestrained electroelastomer films around compression spring, we demonstrated Multifunctional Electroelastomer Rolls (MERs) that combine load bearing, actuation, and sensing functions. The MER spring rolls are potentially high...
The rehabilitation community is at the threshold of a new age in which orthotic and prosthetic devices will no longer be separate, lifeless mechanisms, but intimate extensions human body-structurally, neurologically, dynamically. In this paper we discuss scientific technological advances that promise to accelerate merging body machine, including development actuator technologies behave like muscle control methodologies exploit principles biological movement. We present state-of-the-art...