
How to Turn Any Material or Surface into a Sensor - jonbaer
https://www.pddnet.com/news/2013/11/how-turn-any-material-or-surface-sensor
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gregsq
Or you could play with this over I2C with one GPIO for interrupt handling.

[https://www.sparkfun.com/products/9695](https://www.sparkfun.com/products/9695)

