Inexpensive, unperfumed hairspray has proven to work the best as a dielectric on top of bare copper. Your experimentation in this area would be very helpful, though! One helpful/unhelpful aspect of using harispray as a dielectric is that it can be fully removed with a bit of soap and warm water. If, over time, your electrode seems to be more conductive (not as strong-feeling, and possibly a little “sparkly” when you touch it without moving your finger), it’s possible to refresh the electrode by washing off all the dielectric and, once dry, spraying a new coat over it. I use a pipette to drip a second layer of hairspray over my first spray coat.
A very thin layer of nail polish (thinned down with lacquer) might also work, but normally-applied nail polish does not work well. Neither does kapton tape, masking tape, Scotch tape, Saran Wrap, or paper. Please try more dielectrics and let me know what works for you! Some things we’ve yet to try:
- Nail polish thinned down with acetone
- Thin lacquer
- Very thin castable silicones, like those from Smooth-On™
- Aluminum cans (the foodsafe coating works well as a dielectric)
- Bare or patinated copper
- Other metals with an oxidation layer on them
High-voltage part of PCB
You’ll notice that there is one corner of the WEFT UI Board that has cross-hatched silkscreen on it—that is just a visual alert that the pins in that area are high voltage (about 200vpp). The driver is current-limited, but it’s wise to be aware of this are of the board so you don’t lean it on something metal, etc.
Calibration and adjustment
In the WEFT Library, there are a few ways you can alter the gross strength of the DRV2667’s output signals. The most effective adjustments are Analog Gain and Digital Gain. If you experience problems with perceiving any electrovibration effect at all, these two settings are the first things to fiddle around with.