High-Performance Flexible Capacitive Pressure Sensor Based on a Spiked Nickel/Polyimide Composite Nanofiber Membrane

Flexible capacitive pressure sensors are now widely used in the fields of electronic skin, medical monitoring, and human-computer interaction. However, most of the current flexible capacitive pressure sensors generally suffer easy saturation and low sensitivity under high pressure. This paper proposes a new strategy using evenly distributed spiked nickel (Ni) particles as fillers in a nanofiber membrane to prepare flexible capacitive pressure sensors. The spiked Ni particles are embedded into the interior of polyimide (PI) electrospun nanofiber membranes by electrostatic self-assembly. The experimental results show that the introduction of spiked Ni particles effectively increased the sensitivity of the sensor under high pressure due to the formation of many parallel microcapacitors. In addition, a novel combination method is adopted to integrate individual sensor modules into arbitrary sensor arrays for sensing field pressures. Specifically, the sensor prototype with a 2.7 weight ratio of spiked nickel/PI nanofiber membranes was characterized by short response/recovery times (30/40 ms), wide pressure detection range (1.5 MPa), and excellent mechanical stability (1000 cycles), more than 4-fold increase in sensor sensitivity (4.04 MPa^-1 at 0-1.5 MPa) compared to pure PI nanofiber membrane dielectric layers. Due to its superior performance demonstration, the sensor could be applied in many scenarios, such as human motion detection, sleeping posture monitoring, and plantar pressure measurement, indicating good application prospects in diverse wearable systems.