What about those of us with prosthetic hands who can't use touch screens for lack of capacitive coupling?
You know they have gloves with capacitive fingertips now so you can use such devices, right? They don't depend on your fingertip's capacitance. That's a solved problem.
Actually, it's a problem I solved for Bochs when I worked at Google. Because I had the need to solve the same problem for a robot that needed to be able to capacitively couple with touch devices. The gloves only work because they are conductively connected to a great big meat antenna (you), such that the cpacitive coupling works.
If you have an artificial limb, there's generally no electrical coupling to the meat antenna. So people with artificial limbs do not get to use touch devices.
The fix is to place a conductive film in the plasticine coating, and to hook it up to an antenna. It's a relatively simple hack, and you can pretty much use any WiFi or Cellular modem antenna from a laptop to do the trick.
And then, voila! Magically able to use touch screen devices. The prototype allowed a man in Germany to use the touchpad on his Lenovo Thinkpad for the first time in his life. Which meant he didn't have to carry a mouse around, since both his arms were prosthetic.
Yes, I am a genius. I'll even let you hire me if you have something interesting to work on. You probably don't.