Pressure Sensor - Woolen Ball

What does the sensor do?

It can be used as a squeeze sensor that only senses squeeze actions. It is still classified as the pressure sensor because they share a very similar input mechanism. The greater the squeeze force, the smaller the resistance would be.

How it works?

The resistance is measured between ends of the thread that bundles the ball of threads. When squeezed, the spacing of conductive carbon particles on the ball will be reduced, and its resistance will decrease.

You will need:

• carbon black ink and polyurethane
• wool yarn
• conductive silver fabric

Sensor structure & Fabrication steps

• Dip-coat (the ball will be all black) or partially-dip-coat (the ball will retain the color of yarns) wool yarns.

• Use the coated yarns and follow the instructions to make the woolen ball. Notice: when tying clumps of yarns together with a single yarns, extra length is required for that yarns, since it needs to be further connected to the circuit.
• Connect with silver fabric.

Application scenarios

It can be used as an interesting fabric input in smart home applications, wearables, etc. For example, it can be an on-off switch that controls a lamp: when squeezed, the lamp will turn on. People can also find an instinctive application of the ball in woolen hats, where many intersting interactive functions can be realized. Can't wait to see what users can create with the woolen ball input.