Comparison Among Low Temperature Piezoelectric Flexible Sensors Based on Polysilicon TFTs for Advanced Tactile Sensing on Plastic

In this work, we present a comparison among four different piezoelectric materials (PVDF-TrFE, Piezopaint, AlN and ZnO), all deposited at low temperature (from RT up to 160 degrees C) on flexible substrate such as thin Polyimide, in order to investigate their possible implementation as flexible tactile sensors. Flexible capacitive sensors were tested by using a mini-shaker, investigating the sensors behavior in force and frequency with the intent of mimicking the human sense of touch. We optimized the piezoelectric properties of the materials by using specific texturing buffer layers or maximizing the poling procedure to increase the dipole alignment. Finally, by using a multi-foil approach, the different sensors have been integrated with polysilicon thin film transistor fabricated on flexible substrates and the specific device sensitivity was evaluated.