Flexible pressure sensor based on multi-layer with gradient structure P(VDF-HFP)/MXene/BaTiO3 composite film for human motion monitoring

In recent years, flexible pressure sensors have been widely used in fields such as human health monitoring, flexible energy storage, wearable electronic devices, and flexible sensing due to their advantages of simple and efficient preparation process, highly sensitive, fast response, and strong piezoelectric performance. In this paper, we studied a kind of polyvinylidene fluoride hexafluoropropylene (P(VDF-HFP))/MXene/BaTiO3 nanofiber prepared by electrospinning technology, and designed a multi-layer structure system with gradient to prepare a flexible pressure sensor. The piezoelectric properties, mechanical properties and dielectric properties are obviously improved. At the same time, the addition of nano fillers and structural design have increased the sensitivity of multi-layer composite fiber membrane-based sensors by 16.5 times compared to pure P(VDF-HFP) in the low-pressure range (<1 kPa), and by 1.5 times compared to PFP-0.5M5BT nanofiber-based sensors, reaching 0.23 kPa−1. When pressed by the palm of the hand, the output voltage of the three-layer gradient structure thin film sensor can be up to about 100 V. Compared with the output voltage of 5 V when the P(VDF-HFP) thin film is pressed by the palm, the output voltage of the flexible pressure sensor of the three-layer gradient structure thin film after adding the filler is 20 times higher. The flexible pressure sensor can analyze and recognize the form of human motion based on the peak, frequency, and shape characteristics of the voltage signals generated by different forms of human motion. This makes it possible for flexible pressure sensors to be used in pressure detection, flexible sensing, electronic skin sensors and other fields.