Robust Flexible Pressure Sensors Made from Conductive Micropyramids for Manipulation Tasks

Flexible pressure sensors that can robustly mimic the function of slow-adapting type I (SA-I) mechanoreceptors are essential for realizing human-like object manipulation in artificial intelligent (AI) robots or amputees. Here, we report a straightforward approach to highly sensitive and robust flexible pressure sensors with fast response time and low operating voltage based on conductive micropyramids made of polydimethylsiloxane/carbon nanotube composites. Both numerical simulations and experimental studies show that the pressure-sensing properties of the devices can be systematically tuned by the spatial arrangement of micropyramids. In particular, by tailoring the ratio between the spacing and the pyramidal base length, the optimal pressure sensors can be achieved with a combination of high sensitivity in both low-pressure (<10 kPa) and medium-pressure (10-100 kPa) regimes, rapid response, high mechanical robustness, low operating voltage, and low power consumption, along with linear response and low hysteresis in the medium-pressure regimes. The optimized pressure sensor is further used for constructing a wearable pressure-sensing system that can convert the amplitude of pressure to wirelessly transmittable frequency signals (spikes) with nearly linear response, closely mimicking SA-I mechanoreceptors. Furthermore, we demonstrate that the high uniformity and scalability of the pressure sensors enable large area pressure-sensing arrays for spatially resolved pressure mapping.