Flexible P(VDF-TrFE) Shared Bottom Electrode Sensor Array Assisted with Machine Learning for Motion Detection

Lightweight, flexible and distributed-pixel piezoelectric sensors are desired in activity monitoring and human–machine interaction (HMI). In this work, a flexible P(VDF-TrFE) piezoelectric sensor array using ITO-coated PET substrate as the shared bottom electrode is demonstrated. The traditional array fabrication, which connects an individual sensor unit into an array, could easily lead to the signal discrepancy due to fabrication and assembly errors. To this end, this work introduces the shared ITO-coated-PET substrate and proposes a synchronous-fabrication method for generating the same thickness of every P(VDF-TrFE) sensor unit through a single spin coating. The designed Au top electrodes were sputtered on the spin-coated P(VDF-TrFE) to form the sensor array at one time without additional assembly step, further ensuring unit consistency. The performance of the cross-shaped sensor array was tested under cyclic compressing–releasing agitation. The results of the positive compression test show that our sensor array has a high consistency. Then, the cross-shaped array design that covers the central position is put forward, which realizes tactile sensing ability with a small number of units. Moreover, the fabricated flexible multi-pixel sensor has the advantage of sensitive identification of different contact scenes, and a recognition accuracy of 95.5% can be obtained in different types of hand touch through the machine learning technology.