Long Stacked EAP Actuator

A multi layer stacked Electro Active Polymer (EAP) actuator with hundreds of layers producing significant deformation has been built successfully at Empa - Material Science and Technology - Switzerland.

Category:

Science & Technology

Tags:

• Stack
• soft
• long

[silvainmichel]

Theoretically there are no limits in miniaturisation. Practical limitations of the production process are the limitations: If You assume an activation voltage of 2.5 kV then You need a passive isolation layer around the active circle of approx. 0.5 mm. Because the passive area should be (much) smaller than the active area I would assume that a minimum area of 300mm^2 is the practical limit (radius of approx. 9mm) . This is what we made.

[silvainmichel]

It was a hand made process... time consuming I know.

[silvainmichel]

In principle yes. We need a space holder to keep the electrodes apart. This thin material (thin to reduce the activation voltage) must withstand a high electrical field. So a high electrical breakdown strength is required. This is the major material requirement for EAPs. The most known EAP material (VHB 4910) was found by SRI in a broad search among all kind of soft materials. I think trash bags are too stiff and clue has not a sufficient structural integrity for practical applications.

[silvainmichel]

There are approx. 1100 layers.

[honinbo82]

What materials did you use and how did you bond the single layers to each other? Did you use an adhesive?

[silvainmichel]

@honinbo82

The material is a IPN-modified acrylic elastomer. IPN stands for Interpenetrating Network. The basic material is a VHB-folie from 3M. Details can be found in the following paper: Sensors and Actuators A 155 (2009) 299 - 307 and Polym Int 2010 59 384 - 390

The layers are not bonded together by a special adhesive but only due to the remaining stickiness of the modified acrylic. In addition, during activation the layers are being hold together by the electrostatic pressure.

[shunt3d]

I can't believe this doesn't have millions of views - nice work!

If the actuator is about 90mm long and there are 1100 layers, does that mean that each Dielectric layer is about 0.08mm thick? I'm assuming that you're counting electrode layers as well, and that the electrode and dielectric layers are the same thickness. If so, how is a 0.08 thick layer of VHB able to withstand the voltage (for lifting 2600g) of 4kV? And when it contracts by 7%, it would become even thinner...

[chinyw01]

May I know what is the time response of this stack?

[MoralDecimation]

How small might these be produced someday?

[jag9998]

Won't basically any kind of thin, compressible plastic sheet work?  Could I use thin trash bags and glue?