Phase Separation Manipulated Gradient Conductivity for A High-Precision Flexible Pressure Sensor

Piezoresistive pressure sensors, analyzing and converting external pressure signals to readable electrical signals for monitoring human health, are always subjected to simultaneously possess high signal-linearity and signal sensitivity. Analogous to the control of sophisticated microstructure for increasing active sensing area, the control of gradient conductivity should enable a linear response via regulating the formed saturation current. Here, inspired by phase separation showing the feasibility of controlling material microstructure and conductivity, a high-performance flexible pressure sensor via the simultaneous control of microgroove structure and wide-range gradient conductivity is demonstrated. First, a laser-etching and dopamine (DA)-doping synergistic approach is used to induce selective phase separation in poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS), achieving broad conductivity modulation (from 297 to 4525 S cm −1 ) and precise microgroove pattern (15.5 µm). Then, by designing conductivity-gradient PEDOT: PSS-based multi-sublayers and microgroove interlocked structure, the sensor shows extraordinarily comprehensive performance of excellent stress-sensing sensitivity (4 × 10 5 kPa −1 ), high linear responsiveness (99.85%) and wide-range sensing ability (up to 100 kPa). Consequently, this sensor reveals excellent capability in detecting multi-mode pressure changes and is expected to branch out into other electronic device designs as a general strategy for the precise manipulation of material physical-chemical properties.