Ferroelectret based flexible keyboards and tactile sensors

Electronics becomes flexible, allowing for electronic devices that can be folded and unfolded for packaging and storage. Such electronic devices require flexible and reliable keyboards and tactile sensors, which may be successfully integrated in textiles and artificial skins. Conventional applications may also benefit from paper-thin, even highly elastic and conformable interfaces. Cellular polypropylene ferroelectrets, with their large piezoelectric response, not affected by bending, seem ideally suited for paper-thin large area keyboards. Here we use this electret material for the preparation of ultra-flexible keyboards with a minimum number of connecting wires. This is achieved by a multilayer architecture, with charge patterns providing ternary coded current traces for identifying the keys.