Composite Porous Polyimide Film-Based Piezoelectric Sensors for Harsh Environments

Porous polymeric piezoelectric materials can effectively increase the contact surface area and promote piezoelectric output performance. However, poor high-temperature resistance and limited mechanical properties greatly restrict their application in harsh environments. Herein, a series of fluorine-containing porous polyimide (FPI) composite flexible films with high voltage output and exceptional temperature resistance are prepared via a water vapor-induced phase separation method. Moreover, the incorporation of boron nitride nanosheets (BNNSs) has not only markedly improved the piezoelectric properties of the fabricated sensor but also substantially enhanced the thermal conductivity of the flexible porous FPI films. In addition, the fabricated FPI composite films exhibit low dielectric characteristics, a high tensile strength of 6.9 MPa, and hydrophobic properties. As a flexible piezoelectric sensor, the FPI films can achieve an excellent piezoelectric output (21.2 V), fast response time (8 ms), and outstanding durability (>9000 cycles). This work demonstrates an effective approach for the structural design of piezoelectric sensors in harsh environments and the flexible wearable field.