Design of flexible nano pressure sensor based on BiCl₃/P(VDF-TrFE) composite film and application in force sensing flexible keyboard

The organic piezoelectric sensor prepared by electrospinning is better flexibility, light weight and breathability than the traditional pressure sensor, which has attracted much attention in the field of wearable sensor research. In this paper, a method of preparing BiCl₃/P(VDF-TrFE) composite film by electrospinning was proposed, and the flexible piezoelectric sensor was designed and prepared with the composite film as the functional layer. After a certain amount of BiCl₃ was added, the scanning electron microscope analysis showed that the average diameter of the fiber increased from 619 nm to 1158 nm, and the surface became smoother. The X-ray diffraction pattern confirmed the stability of the composite film β phase content has been significantly improved. The piezoelectric response testing results show that the peak to peak V_oc and I_sc of P(VDF-TrFE) composite films with 2wt% BiCl₃ are 16.8 V and 164 nA, Compared with pure P (VDF TrFE) piezoelectric film, it is obviously improved, 215% and 224% times. The pressure sensing testing results show that the piezoelectric film is good linear output characteristics under the pressure of 1.28 N. A flexible wearable force sensing keyboard was designed with this film, which can collect fingers pressing force and duration time. And it provides a reference solution on smart fabrics such as flexible keyboard applications.