High-sensitivity LC wireless passive flexible pressure sensor based on anisotropically distributed nmFe with dual-sensitivity mechanism

Abstract Aiming at the problem that the sensitivity of LC pressure sensors is restricted due to the use of single inductance or single capacitance sensing mechanisms, the paper proposes a highly sensitive flexible LC pressure sensor based on a dual-sensing mechanism. The anisotropically distributed nano-iron particles doped porous polydimethylsiloxane (PDMS) film and ferrite film are respectively used as the capacitance and inductance sensitive layers of the pressure sensor. The capacitance is affected by the change in dielectric constant of the porous PDMS film under different compression states. The change in distance between the LC resonant circuit and the ferrite film will cause a change in the effective magnetic permeability, hence achieving a controllable response of the inductance in the LC circuit. Based on the dual sensitive mechanism of the cooperative response of inductance and capacitance under pressure, the resonant frequency of the LC sensor can be significantly shifted, thereby breaking through the limitation of improving the sensitivity of the LC pressure sensor. In addition, ferrite films can effectively shield metal signal interference, consequently enhancing the stability and accuracy of wireless detection signal transmission performance. Within the pressure range of 0–10 kPa, the sensitivity of the sensor is 434.64 kHz kPa −1 , the signal quality factor is 30, and the maximum hysteresis error and maximum repeatability deviation are less than 0.723% and 0.4 MHz respectively. Through the dual sensitivity mechanism of inductance and capacitance, the sensor achieves highly sensitive pressure detection. Its flexible structure and high sensitivity are particularly suitable for applications such as wearable health monitoring and human–computer interaction, and provide new ideas for the optimized design of flexible LC pressure sensors.