This sensor can detect bending in one direction. They were popularized by being used in the Nintendo PowerGlove as a gaming interface. These sensors are easy to use, they are basically resistors that change value based on how much their flexed. If they’re unflexed, the resistance is about ~10K. When flexed all the way the resistance rises to ~20K. You can use an analog input on a microcontroller (with a pull-up resistor) or a digital input with the use of a 0.1uF capacitor for RC timing. The bottom part of the sensor (where the pins are crimped on) is very delicate so make sure to have strain relief – such as clamping or gluing that part so as not to rip out the contacts!