Electricity from the Ocean Waves - Wacker Chemie AG

Electricity from the Ocean Waves

Since electroactive polymers convert mechanical into electrical energy, silicone films are also suitable for use in sensors.

as thin as 20 micrometers.

To operate such a base unit as a dielectric elastomer actuator, a voltage must be applied. The level of this operating voltage depends on the film thickness – the thinner the elastomer film, the lower the voltage needed. The actuators currently in development typically have film thicknesses between 20 and 60 microns, and are therefore much thinner than a human hair. The voltages involved are in the order of several kilovolts. At these levels, the thickness of the film decreases by 5 to 30 percent, with the exact figure depending on the material. At the same time, the surface area typically increases by 50 percent.

Application of a voltage to a single actuator base unit produces a deformation of just a few microns. That is not enough for industrial use. However, if large numbers of them are stacked together and connected up in parallel, changes in the order of several millimeters and even centimeters are possible. These stacks, which can have any shape, can be used to generate different types of movement.

Relays, Switches and Valves

EAP actuators are lightweight, can be controlled with precision and are extremely efficient. The word has got around, particularly in the electrical sector. Relays, switches and valves based on dielectric elastomer actuators are almost ready for launch, and should reach the market in the next two to five years. EAP actuators are also set to be used in the automotive industry, where they could eventually replace electric servomotors. In contrast to their conventional electromagnetic counterparts, EAP relays only require power when switching. Considering that relays are found in vast numbers of devices and equipment, the energy-savings potential is huge. Another potential beneficiary of EAP technology is the valve industry, where EAP actuators would provide precision control over fluid flow, a task not readily mastered by conventional fluid valves.

With No Material Fatigue

A further important property is the films' exceptional resilience. Their dielectric, mechanical and elastic properties do not vary with the applied voltage or the temperature. Nor do they deteriorate over time, a fact which gives silicone films the edge over dielectric films based on organic polymers. “The property profile of the films is typical of silicones, making EAP parts rugged, durable and low-maintenance,” explains WACKER chemist Dr. Andreas Köllnberger. “Our trials on prototypes have shown silicone films to survive over ten million compressive cycles without the slightest fatigue.”