Research on an Ionic-Electronic Dual-Mode Flexible Strain Sensor with Integrated High Sensitivity and Broad Sensing Range

This study proposes a new type of ion-electron dualchannel flexible strain sensor. The sensor can simultaneously achieve ultra-high gauge coefficient and wide sensing range, effectively breaking through the long-standing performance limitations of flexible sensing technology. The sensor adopts a dual-channel stacked structure and cleverly integrates two functional layers: one is a microstructured electronic conductive layer, which forms wrinkles and micro-cracks through a pre-stretching process; the other is a highly elastic ion gel layer based on the PVC/DBA/EMIM-TFSI material system. This design enables dynamic adaptive switching of conduction paths. In the low strain stage ($0-35 {\%}$), the electron shell plays a dominant role. The gradual expansion of microcracks causes the resistance to increase exponentially, with a gauge coefficient as high as 25,138, which can be used to capture weak physiological signals such as pulses. As the strain continues to increase, the ion layer takes over the dominance under large deformation conditions. Its resistance change is determined by geometric deformation, and its response linearity is good, which expands the sensor monitoring range to 200% and is suitable for monitoring large-scale movements such as joint activities. On a dual-channel stack basis, the sensor also exhibits an excellent combination of performance metrics, with a low detection limit of 0.1% and excellent cycle durability, with over 90.7% signal retention after 1,000 vigorous stretch-release cycles at 200% strain. By utilizing these combined capabilities, the sensor successfully achieves high-precision acquisition of subtle physiological signals, and in this study, detailed arterial pulse waveforms of the characteristic signals$\mathrm{P}, \mathrm{T}$, and D peaks for cardiovascular assessment, as well as motion signals of various joint movements, were acquired. This research has great potential for wide application in the fields of next-generation wearable health monitoring devices, soft robots, and advanced human-machine interfaces, and provides a new reference for the development of high-performance flexible electronic products.