Bioinspired gradient stretchable aerogels for ultrabroad-response-range wearable pressure sensors

With the increasing demand for electronic skin, health management, and extreme pressure monitoring, development of broad-response-range flexible pressure sensors is in urgent need. However, the reported flexible pressure sensors usually show a narrow detection range. It’s a great challenge to achieve a broad detection range of 1 Pa-10 MPa for a flexible pressure sensor. Herein, unprecedented bioinspired wearable pressure sensors based on highly stretchable reduced graphene oxide/polyurethane foam composite aerogels with modulus-gradient porous structures have been reported. A hot pressing method is applied to increase the modulus and compressive strength of the high-modulus layer of the aerogel, which ensures their compressibility at high pressures and significantly enhances the upper detection limit. Benefiting from their unique superelastic (90-99% reversible strain) and gradient structures with the gradient modulus spanning from 5.4 kPa to 430 kPa and gradient compressive stress (at 90% strain) spanning from 25 kPa to 37 MPa, the resulting pressure sensors exhibit a record-breaking detection range of 1 Pa-12.6 MPa. In addition, the pressure sensors can withstand 10000 cycles at a high pressure of 1 MPa, which can’t be achieved by traditional flexible pressure sensors. This work provides a versatile and powerful strategy towards next-generation high-performance broad-response-range flexible electronics.