Colin and I needed to find some way to attach wearable electronics to the body for body jewelry and wearable computing type applications. Eventually we hope piercing and other body modification technologies will allow us to do permanent attachment, but despite recent articles on people using sub-dermal for the task, they're are WAY to prone to rejection to think about hanging things off of them. Sub-dermal magnets, too, come up short currently as they destroy the skin when paired with an external magnets/ferrous objects.

So what we needed was a double sided adhesive that stuck well to FR4 PCB boards, had a foam type carrier (ie it was thick) so some electronics could sit flush, and was something we handle and package reliably.

TLDR - You can't beat medical grade adhesives from 3M. They stick more reliably than anything else, and can be reapplied if they are removed. We sampled basically all of them and found them frankly equal for our purposes. However, only one had a foam carrier, good old 4133 med spec tape packets pk000023198. (update: these used to be called 3M Venture #7432M and you can actually find them by googling for that) After you sample they'll refer you to a 'converter' who will actually die cut and or sell it to you, though we still haven't been able to get a quote out of our local converter.

There were other adhesives worth mentioning but which didn't fit our application for whatever reason.

We tried everything from the hardware store. Largely they didn't work well at all:

• 3M foam tape. Seems to be rubber and acrylic versions if you dig deep enough. Acrylic is way more common and might have seemed stronger, but not by much. Digikey stocks 4026, the stronger version, which we liked best of the hardware store tapes.
• 3M VHB is also apparently acrylic, but didn't work well for us.
• Carpet tape from hardware store didn't work at all either.

Theres also toupee tapes/bra tapes which all seem to be identical. They're very thin double sided tapes but worked very well. Im not sure how different from any other double sided tape from Staples, so thats left as an exercise for the reader. They claim they're hypoallergenic so the adhesive is probably not latex.

• Vapon Topstick
• Hollywood Fashion Tape

We also tried every kind of prosthetics/medical adhesives we could get our hands on. All had a similar issue for us of being unwieldy to package and apply, but would work great for any other application:

• Pros-aide, Pro adhesive or Reel Magic (a hundred names for the same product) - a prosthetics glue used in costuming and makeup. Its thick and milky like paste. A good hold. Most claim to be latex free/hypoallergenic.
• Tensive - A conductive gel (might be interesting for some application?) normally used for TENS/TEMs devices. Had a pretty good hold.
• Osto-bond - Latex based so some people, surprisingly including me, might be allergic. Was pretty good though otherwise.
• Skin tac. Very thin and watery. Leaves a tacky membrane to stick things to that wasn't as strong as other options, but could be good for plastics or something. Also, hypoallergenic as its latex free.