Melamine Foam Functionalized with a Plastic-Crystal Electrolyte for Advanced Iontronic Pressure Sensors

Iontronic pressure sensors (IPSs) with foam-based microstructures have exhibited greatly enhanced sensitivity compared with other types of IPSs. Nevertheless, ion leakage and limited structural compressibility prevent them from achieving satisfactory stability and a broad pressure range. Herein, a novel IL-like plastic-crystal electrolyte (PCE) is introduced into a polymeric melamine foam (MF) skeleton to prepare an ionic dielectric layer for IPS. The incorporation of PCE not only produces an extra EDL capacitance contribution but also promotes the structural compressibility of the dielectric layer. Consequently, the MF/PCE sensor exhibits a high sensitivity of 0.16 kPa⁻¹ within 1.0 MPa and a relatively high sensitivity of 0.08 kPa⁻¹ within the ultrabroad pressure range of 1.0-2.8 MPa. Owing to the solid state of PCE at ambient conditions and its good compatibility with MF, the composite film does not experience any ion leakage or solid detachment issues, even at large compression pressures. Therefore, the resultant MF/PCE sensor exhibits remarkable durability over 8300 cycles at a large pressure of 85 kPa. The MF/PCE sensor is successfully applied to assess yoga pose accuracy and detect plantar pressure distributions. Our MF/PCE sensor displays great promise in human motion detection and provides an economic and convenient method for real-time sports performance monitoring.