An iontronic flexible pressure sensor based on a multistage gradient micro-dome structure with a broad sensing range for wearable devices†

In recent years, despite the extensive evolution of capacitive flexible pressure sensors, conventional capacitive pressure sensors are constrained by structural hardening, resulting in a limited pressure-response range. Here, an iontronic flexible pressure sensor based on a multistage gradient micro-dome structure was reported. The multistage gradient structure not only enhances the compressibility of the device, but also reduces the initial contact area. In addition, the sensor uses AgNWs as electrode materials to ensure that excellent electrical conductivity is maintained over a certain strain range, while polyvinyl alcohol and [BMIM]BF₄ are employed as ionic layers to improve the performance of the ionic materials. The sensor achieves a maximum sensitivity of 8.1 kPa⁻¹ within a pressure range of 2.1 Pa–600 kPa, and a fast response/recovery time of 25/20 ms. Moreover, it repeats compression/release 3000 times at a pressure of 26 kPa without significant signal drift. The sensor can identify different sitting positions and monitor laryngeal activity in wearable devices with strong repeatability and dynamic response recovery, enabling users to adjust incorrect sitting postures in a timely manner.