These gloves were originally made as part of the Perfect Human performance, and were exhibited separate from the performance in an exhibition space, which allowed for the audience to get a feel for how it might be to wear the whole Puppeteer Costume.

Exploring the use of affordable, off-the-shelf materials and basic techniques to create wireless motion capture wearables.

These sensors measure pressure and can also be designed and placed to measure bend. They work on the simple principal that Velostat reacts to pressure with a decrease in electrical resistance. When sandwiched between two conductive layers, this change in resistance can be easily measured and used as an indication of how much pressure is [...]

also: neoprene bend sensor, conductive thread Bend Sensor, Bend Sensor (thread)
This bend sensor actually reacts (decreases in resistance) to pressure, not specifically to bend. But because it is sandwiched between two layers of neoprene (rather sturdy fabric), pressure is exerted while bending, thus allowing one to measure bend (angle) via pressure.