Synergistic Effect of Gradient Conductivity and Gradient Microstructures Enabled Ultrasensitive and Ultrabroad Linear...

The decoupled optimization on sensitivity and linearity is crucial for exploiting high-performance flexible tactile sensors for diversified applications while remaining challenging. Here, a novel design of conductivity-microstructures double gradient effect constructed by the rough surface-based flexible electrode and the arched microstripes-based carbon-Polydimethylsiloxane/silver nanowires (CPDMS/AgNWs) electrode is presented. Different from conventional strategies, the top-down configuration of low-conductivity CPDMS and high-conductivity AgNWs enables the pressure-induced gradient conductivity effect to allow the linearly varied current during the CPDMS deformation. The gradient microstructures of the rough surface and arched microstripes further render the sequential trigger of the gradient conductivity-induced linear current under different pressures, which accordingly contributes to the ultrawide linearity range upon rationally constructed structural gradient. Besides, the gradient conductivity effect can initially grant the dramatically enhanced sensitivity without depending on structural adjustments. The sensitivity and linearity can thus be optimized without mutual restriction. The proposed sensor exhibits the ultrahigh sensitivity of 5642.02 kPa^-1 and ultrawide linear response of 0-1560 kPa, which is first reported. The synchronously achieved ultrahigh sensitivity and ultrabroad linearity allow the successful demonstrations of reliable detection of physiological signals for healthcare monitoring, convenient lighting control for smart home, and accurate object identification for intelligent sorting.