Dielectric elastomer artificial muscles (Energy harvesting and high-efficiency actuation) (original) (raw)
Related papers
2011
Electrically deformable materials have a long history, with first quotations in a letter from Alessandro Volta. The topic turned out to be hot at the end of the 19th century, with a landmark paper of Röntgen anticipating the dielectric elastomer principle. In 2000, Pelrine and co-workers generated huge interest in such soft actuators, by demonstrating voltage induced huge area expansion rates of more than 300%. Since then, the field became mature, with first commercial applications appearing on the market. New frontiers also emerged recently, for example by using dielectric transducers in a reverse mode for scavenging mechanical energy. In the present survey we briefly discuss the latest developments in the field.
Dielectric elastomer generator with equi-biaxial mechanical loading for energy harvesting
SPIE Proceedings, 2013
Dielectric elastomer generators (DEGs) are attractive candidates for harvesting electrical energy from mechanical work since they comprise relatively few moving parts and large elastomer sheets can be mass produced. Successfully demonstrations of the DEG prototypes have been reported from a diverse of energy sources, including ocean waves, wind, flowing water and human movement. The energy densities achieved, however, are still small compared with theoretical predictions. We show that significant improvements in energy density (550 J/kg with an efficiency of 22.1%), can be achieved using an equi-biaxial mechanical loading configuration, one that produces uniform deformation and maximizes the capacitance changes. Analysis of the energy dissipations indicates that mechanical losses, which are caused by the viscous losses both within the acrylic elastomer and within the thread materials used for the load transfer assembly, limits the energy conversion efficiency of the DEG. Addressing these losses is suggested to increase the energy conversion efficiency of the DEG. .
Dielectric elastomer artificial muscle actuators: Toward biomimetic motion
2002
To achieve desirable biomimetic motion, actuators must be able to reproduce the important features of natural muscle such as power, stress, strain, speed of response, efficiency, and controllability. It is a mistake, however, to consider muscle as only an energy output device. Muscle is multifunctional. In locomotion, muscle often acts as an energy absorber, variable-stiffness suspension element, or position sensor, for example. Electroactive polymer technologies based on the electric-field-induced deformation of polymer dielectrics with compliant electrodes are particularly promising because they have demonstrated high strains and energy densities. Testing with experimental biological techniques and apparatus has confirmed that these "dielectric elastomer" artificial muscles can indeed reproduce several of the important characteristics of natural muscle. Several different artificial muscle actuator configurations have been tested, including flat actuators and tubular rolls. Rolls have been shown to act as structural elements and to incorporate position sensing. Biomimetic robot applications have been explored that exploit the muscle-like capabilities of the dielectric elastomer actuators, including serpentine manipulators, insect-like flappingwing mechanisms, and insect-like walking robots.
Maximizing the Energy Density of Dielectric Elastomer Generators Using Equi-Biaxial Loading
Advanced Functional Materials, 2013
Dielectric elastomer generators (DEGs) for harvesting electrical energy from mechanical work have been demonstrated but the energy densities achieved are still small compared with theoretical predictions. We show that significant improvements in energy density (560 J/kg with a power density of 280 W/kg and an efficiency of 27%) can be achieved using equi-biaxial stretching, a mechanical loading configuration that maximizes the capacitance changes. We demonstrate the capacitance of dielectric elastomers subjected to equi-biaxial stretches is proportional to the fourth power of the stretch. Quantification of the individual energy contributions indicates that attaining higher conversion efficiencies is limited by viscous losses within the acrylic elastomer, suggesting that still higher conversion efficiencies with other elastomers should be attainable with our novel mechanical loading design.
Dielectric Elastomer Energy Harvesting and its Application to Human Walking
Volume 2: Biomedical and Biotechnology Engineering; Nanoengineering for Medicine and Biology, 2011
Human walking requires sophisticated coordination of muscles, tendons, and ligaments working together to provide a constantly changing combination of force, stiffness and damping. In particular, the human knee joint acts as a variable damper, dissipating greater amounts of energy when the knee undergoes large rotational displacements during walking, running or hopping. Typically, this damping results from the dissipation, or loss, of metabolic energy. It has been proven to be possible however; to collect this otherwise wasted energy through the use of electromechanical transducers of several different types which convert mechanical energy to electrical energy. When properly controlled, this type of device not only provides desirable structural damping effects, but the energy generated can be stored for use in a wide range of applications. A novel approach to an energy harvesting knee joint damper is presented using a dielectric elastomer (DE) smart material based electromechanical transducer. Dielectric elastomers are extremely elastic materials with high electrical permittivity which operate based on electrostatic effects. By placing compliant electrodes on either side of a dielectric elastomer film, a specialized capacitor is created, which couples mechanical and electrical energy using induced electrostatic stresses. Dielectric elastomer energy harvesting devices not only have a high energy density, but the material properties are similar to that of human tissue, making it highly suitable for wearable applications. A theoretical framework for dielectric elastomer energy harvesting is presented along with a mapping of the active phases of the energy harvesting to the appropriate phases of the walking stride. Experimental results demonstrating the energy harvesting capability of a DE generator undergoing strains similar to those experienced during walking are provided for the purpose of verifying the theoretical results. The work presented here can be applied to devices for use in rehabilitation of patients with muscular dysfunction and transfemoral prosthesis as well as energy generation for able-bodied wearers.
Dielectric Elastomers for Energy Harvesting
Energy Harvesting
Dielectric elastomers are a type of electroactive polymers that can be conveniently used as sensors, actuators or energy harvesters and the latter is the focus of this review. The relatively high number of publications devoted to dielectric elastomers in recent years is a direct reflection of their diversity, applicability as well as nontrivial electrical and mechanical properties. This chapter provides a review of fundamental mechanical and electrical properties of dielectric elastomers and up-to-date information regarding new developments of this technology and it's potential applications for energy harvesting from various vibration sources explored over the past decade.
El-Cezeri Fen ve Mühendislik Dergisi, 2021
Dielectric Elastomer Actuator (DEA) consists of a thin dielectric elastomer membrane sandwiched between two electrode layers. When low current high voltage is applied to the two conductive layers, opposite loads occur on the surface which tends to pull one another. This voltage application causes thinning in width and expansion in surface area. DEAs are the favorite subject of research due to their low-cost advantages, fast response, high energy density, wide deformation, and softness. Due to the rigidity of the electric motors and the metal components of the robot, soft-acting robots using DEA are preferred to perform complex tasks instead of conventional robots. Robots with DEA have higher flexibility and better adaptability. Therefore, soft robots are popular topic in robotics research. DEAs are the best candidate materials for next-generation soft robot actuators and artificial muscles. In this study, simulation of the robotic systems has been realized by using DEAs calculation methods. Simulation results were compared with the data obtained from the application. This study will be the source of future studies on the subject. In the simulation, Matlab 2016 student and Labview Home and Students programs were used.
Optimizing the electrical energy conversion cycle of dielectric elastomer generators
Advanced materials (Deerfield Beach, Fla.), 2014
A strategy to control the electrical charge is developed to achieve high energy density of soft dielectric elastomer generators for energy harvesting. The strategy is analytically shown and experimentally demonstrated to produce the highest energy density ever reported for a soft generator.
Method for measuring energy generation and efficiency of dielectric elastomer generators
2011
Dielectric elastomer generators convert mechanical into electrical energy at high energy density, showing promise for large and small scale energy harvesting. We present an experiment to monitor electrical and mechanical energy flows separately and show the cycle of energy conversion in work-conjugate planes. A specific electrical energy generated per cycle of 102mJ/g, at a specific average power of 17mW/g, is demonstrated with an acrylic elastomer in a showcase generation cycle.
Characterization of the effect of energy harvesting on the dynamic response of dielectric elastomers
Electroactive Polymer Actuators and Devices (EAPAD) 2011, 2011
Recent energy harvesting research has developed dielectric elastomer (DE) energy harvesting devices for use in low frequency applications including waves, wind and human motion. The use of dielectric elastomers for energy harvesting is a growing field, which has great potential from an energy density viewpoint. While DE has shown promise for energy harvesting applications such as walking where the mechanical behavior could affect the user, there has been little investigation into the damping effects induced by DE energy harvesting. As devices capable of harvesting larger amounts of energy are developed harvesting-induced changes in the mechanical behavior of the dielectric must be investigated. This paper investigates the structural damping effects of DE energy harvesting in order to develop a more in-depth understanding of the changes in system response due to increased energy harvesting. Results relating energy harvesting strain and bias voltage to damping provide a framework for developing energy harvesting techniques which improve the overall performance of the system.