Flexible large area ferroelectret sensors for location sensitive touchpads

Cellular polypropylene ferroelectrets are flexible transducer materials with dominant longitudinal piezoelectricity. They can be used for transient pressure sensing applications, due to the low cost of the sensor material. The authors show that ferroelectrets allow for the production of keyboards and touch pads with a customizable layout. Large area resistive electrodes on the ferroelectret with electronics at the edges avoid the preparation of complex sensor matrices. A touch pad of 10 × 10 cm 2 area was tested by applying a force of 1.7 N on an area with a diameter of 5 mm in a grid matrix with 23 × 23 elements.