What Is a Dielectric Elastomer?
Dielectric elastomers are a type of elastomer, akin to rubber, that exhibit significant shape changes when exposed to high electric fields. These materials combine elasticity with the ability to act as electrical insulators, making them capable of converting electrical energy into mechanical movement.
With high dielectric constants and softness, dielectric elastomers are under active research for their potential in practical applications that exploit their unique capabilities.
Uses of Dielectric Elastomers
Currently, dielectric elastomers are being explored for future applications such as artificial muscles in actuators. They offer high energy conversion efficiency and are anticipated to lead to the development of compact, energy-efficient actuators that are environmentally friendly, addressing the need for new technologies in a decarbonizing society.
Furthermore, dielectric elastomers have the potential for energy harvesting and sensing applications, leveraging their ability to convert mechanical changes into electrical energy and vice versa.
Principle of Dielectric Elastomers
Dielectric elastomers work by applying electrodes on both sides of an elastomeric material with a high dielectric constant. When high voltage is applied, the resulting Coulomb force causes the elastomer to expand and contract. The applied pressure is a function of the voltage, the material’s dielectric constant, and the distance between the electrodes.
Structure of Dielectric Elastomers
To accommodate large strains, dielectric elastomers are made from soft, stretchable materials such as acrylics and silicones. The electrodes, which must maintain contact with the elastomer through its deformations, can be made from metals, graphite powders, or graphite-silicone oil mixtures. This setup allows for efficient energy conversion with minimal heat loss.
Types of Dielectric Elastomers
Dielectric elastomer actuators can vary in design, offering versatile applications:
1. Forehead Actuator
A simple actuator design with dielectric elastomer-coated electrodes.
2. Cylindrical Actuator
Utilized in valves and micro-robots, this actuator expands axially when voltage is applied, functioning without a core if wrapped around a compression spring.
3. Diaphragm Actuator
A flat membrane that actuates in the z-axis direction, suitable for various applications.
4. Shell Actuator
Features multiple electrodes on an elastomer film, capable of creating complex three-dimensional movements for propulsion in water or air.
5. Laminated Actuator
Offers high force and deformation through a laminated surface design.
6. Thickness Actuator
Generates displacement or force in the z-axis direction, with flat films stacked to enhance movement.