In our experimentation, we accomplished two main objectives: Make a simple flat DEA that moves significantly, and make a RDEA that functions as a capacitor and is usable at high voltage.
We were not able to make a RDEA that moves significantly. We believe this is because of material limitations. We chose Sylgard 184 PDMS because it was easily accessible. However, other variants, such as Sylgard 186, may be more naturally stretchy while maintaining the tear strength needed for ease of manufacturing and reliable performance as an actuator.
During experimentation, we verified Sylgard 184’s reported breakdown voltage of ~20 kV/mm. Our 50 micron thick sample broke down just over 1 kV. It is unclear if variants, such as Sylgard 186, have this same low dielectric constant.
Our breakdown issue was worsened by the difficulty of manufacturing our own PDMS sheets in an environment with dust. Ideally one would be able to do manufacturing in a cleanroom environment to avoid adding defects to the sheets.
The best path forward would probably be to purchase premade silicone sheets. 50 micron PDMS sheets are available for sale online, however the creme of the crop material in this field seems to be Wacker Elastosil 2030, boasting a breakdown voltage 5-10x what we were able to achieve with our samples.
The carbon grease is also not the optimal electrode. The carbon black suspended in the grease is an effective conductor, but the grease itself is messy, difficult to apply evenly, and adds excess material that restricts movement of the DEA. Pure carbon black powder can be used as a compliant electrode, but the percolation network it creates is more easily broken when stretched. The optimal compliant electrode would be a percolation network of carbon nanotubes. The added length of the tubes creates a much more robust network than carbon black, while maintaining the ultra thin, light, and unrestrictive nature of the loose percolation network. We purchased 10 mg of single wall carbon nanotubes, but decided against using them due to safety concerns around their asbestos like properties if inhaled.
If one was to extend our research, the best place to start would be by recreating our process with upgraded materials. However, I would not recommend this as a junior lab project. Ultra thin materials like our PDMS sheets can be a pain in the ass to work with, and there are real health risks involved with high voltage and especially carbon nanotubes.