High sensitivity iontronic pressure sensors with wavy structure electrode and two-level raised structures ionic gel film prepared by direct laser writing

Sensitivity is a critical parameter in flexible pressure sensors, which typically refers to the ratio of the change in the output signal to the change in the input pressure signal. In the design of flexible pressure sensors, although the sensitivity can be enhanced by designing the surface structure of the dielectric, such as a single structure like a hemispherical shape, the sensitivity will decrease as the pressure gradually increases. Furthermore, in most reports, the fabrication of electrodes is particularly cumbersome, which increases the difficulty of preparing the sensor. Here, we propose a fabrication method for a flexible capacitive sensor based on direct laser writing (DLW) technology. Controlled UV direct laser writing of polyimide (PI) was used to prepare a series of different twolevel protruding structures under different laser parameters. In this type of iontronic sensor, the maximum sensitivity is up to 986.8 kPa-1, and the pressure range exceeds 200 kPa. The response/recovery time can reach 10/16 ms and withstand 2500 cycles of repeated loading/unloading under high pressure of 120 kPa. The sensor has good mechanical properties, and high sensitivity, and has been verified by a few applications on the human body. This work demonstrates a simple and convenient method for fabricating electrodes and microstructures, and provides a new approach for future iontronic sensors fabrication.