Flexible, Equipment-Wearable Piezoelectric Sensor with Piezoelectricity Calibration Enabled by In-Situ Temperature Self-Sensing

Flexible piezoelectric sensors have attracted much attention due to good dynamic response, high sensitivity, and self-powered sensing advantages. However, piezoelectric outputs are usually affected by temperature variation, thus limit their applications on industrial intelligent equipment. Here, a new flexible piezoelectric sensor with in situ temperature sensing and piezoelectricity calibration function is developed. The sensor can calibrate the piezoelectric output based on temperature to achieve high-accuracy sensing capability. It consists of a flexible polyimide substrate, S-shaped platinum interdigital electrodes and aligned piezoelectric fibers. The designed S-type electrode with thermosensitive effect measures the temperature in-situ, and then the piezoelectric strain output from P(VDF-TrFE) fibers is calibrated according to the temperature. The temperature sensor has a high sensitivity of 19.2 Ω/°C with good linearity, and keeps good accuracy under bending deformation. When the working temperature range is 25 °C-60 °C, the sensor has a good piezoelectricity calibration effect, so that it maintains a stable sensitivity of 244 mV/μϵ without being affected by temperature. Furthermore, this article systematically studied the influence of temperature on piezoelectric output, and established a calibration method to improve the accuracy of piezoelectric output under temperature changes. Finally, the flexible integrated sensor was conformally attached on the bearing surface to in situ sensing temperature and micro-strain. The structural design and piezoelectricity calibration method can promote the application of flexible piezoelectric sensors in the industrial field.