Initial-Capacitance-Regulated Iontronic Pressure Sensor with Pressure-Activated Interfacial EDL Reconstruction for Wearable Voice Interaction

Abstract Iontronic pressure sensors (IPSs) have attracted considerable attention for low-pressure detection owing to the large interfacial capacitance generated by electrical double-layer (EDL) formation. However, the inherent wettability of ionic media often causes the device to form a relatively high initial capacitance (C0) under pressure-free conditions, which limits the achievable sensitivity. Herein, a hierarchical fibrous network strategy was proposed to regulate C0 and activate pressure-triggered EDL reconstruction. C0 was effectively reduced by limiting the initial ionic medium/electrode contact area, while pressure-induced pore compression enlarges the effective interfacial area and rapidly enhances EDL capacitance. Thus, a flexible pressure sensor composed of a PVDF-HFP nanofiber membrane and ionogel (PNMI) was ultimately developed with an ultrahigh sensitivity of 179.44 kPa–1 over 0–15 kPa. Thus, it enabled accurate pressure signal detection. Assisted by random forest, a highly accurate recognition of seven voice commands was achieved, with an accuracy of 98.5%, demonstrating its potential for wearable human–machine interfaces.