Testing

High Voltage Safety

Depending on the size of your actuator, it can take many thousands of volts to see reliable actuation. For this reason, we insist you review your lab's safety manual on working with high voltages.

Always make sure your actuator is grounded before connecting any voltage source. The high voltage amplifier described in the Bill of Materials section will allow you to amplify a DC voltage source to the required level.

Example testing setup

In this testing setup, the actuator is suspended from above by a clamp and the electrodes are attached to ground (black wire on right) and a voltage source (red wire on left). The actuator was supplied with a square wave signal and the amplitude and frequency were adjusted until the actuator failed.

The following video demonstrates the actuator's response to increasing amplitude with a fixed frequency. In the video, the supplied voltage ranges from 5.4 kV to 7.0 kV, while the frequency of the square wave remains constant at 0.5 Hz. Enable annotations in the YouTube video for labels showing the timing of voltage changes.

In the next video, the signal frequency ranges from 0.5 Hz to 5.0 Hz, while the voltage supplied remains constant at 7.0 kV. The timing of when the frequency changes can be seen if you turn on YouTube annotations.

Loss of Tension

The actuator was then returned to a 0.5 Hz signal frequency and given an increased input voltage of 7.2 kV. At this point, the actuator began showing signs of loss of tension (as discussed in the Modeling section). The folds that appear in the active area are a clear indication of this:

Failure Mode: Electric Breakdown

The actuator continued to operate for another ~45 seconds before it fully failed through electric breakdown (as discussed in the Modeling section). The effect is very quick and can be hard to catch, but it happens around 13 seconds in this video, where you can see a little puff of smoke and the actuation stops:

Bibliography

Keplinger et al. (2012) Harnessing snap-through instability in soft dielectrics to achieve giant voltage-triggered deformation.

Keplinger et al. (2013) Stretchable, transparent, ionic conductors.

Koh et al. (2009) Maximal energy that can be converted by a dielectric elastomer generator.

Wissler and Mazza (2007) Mechanical behavior of an acrylic elastomer used in dielectric elastomer actuators.

Pelrine et al. (2001) Dielectric elastomers: generator mode fundamentals and applications.

Pelrine et al. (2000) High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%.

Röntgen WC. (1880) Ueber die durch Electricität bewirkten Form—und Volumenänderungen von dielectrischen Körpern.

Suo, Zhigang (2010) Theory of dielectric elastomers.

Contributors

Philipp Rothemund