Piezoresistive Polymer Diaphragm Sensor Array Using Conductive Elastomeric Nanocomposite Films for Skin-Mountable Keypad Applications

This paper reports on arrayed piezoresistive polymer diaphragm sensor made entirely of elastomer for skin-mountable keypad applications. Two-step transfer of conductive elastomeric nanocomposites (CENs) combined with soft lithographic techniques enables the achievement of elastic sensing layers with strip-patterned CENs embedded in polydimethylsiloxane (PDMS) channels. After assembling with an elastomeric bump layer, simple all-elastomer sensor architectures are successfully demonstrated. The activated buttons of the sensor can be easily and distinguishably identified by sensing the simultaneous changes in the electrical resistance of CEN strips with respect to the applied force. The straightforward sensing mechanism makes it possible to detect the exact locations of input with negligible crosstalk between adjacent sensing buttons to each other. The usability of the sensor platform as a skin-mountable keypad is also demonstrated by integrating on a wrist.