Pressure?

http://www.pressureprofile.com/finger-tps/

The least ambiguous signal to be sure. But pricey and intrusive.

Would the Robotics Lab or EVL have something I could play around with? According to Wikipedia, the EVL developed the very first wired glove back in 1977.

Or we could try to roll our own for similar functionality like this:

http://www.instructables.com/id/Sensitive-Fingertips/

Or this:

http://www.kobakant.at/DIY/?p=2149