Hydrogels from chrome shavings for a highly sensitive capacitive pressure sensor

Ionic capacitive pressure sensors (CPSs) with excellent performance are urgently desired in the field of flexible pressure sensors. To enhance the sensing performance of ionic CPSs, the surface microstructures and internal structures of sensing materials need to be rationally designed. In this work, a novel and simple strategy is explored to construct microstructured hydrogels based on chrome shavings. The hydrogel displays outstanding performance due to its stable surface synapses and abundant pore structures, which are attributed to the unique structural features and appropriate gelation transition of chrome shaving collagen fibers (CFs). The assembled biomass hydrogel sensor exhibits high sensitivities of 6.01 kPa-1 (0-0.9 kPa), 1.62 kPa-1 (0.9-3 kPa), and 1.22 kPa-1 (3-8.95 kPa). Glycol was introduced to overcome the drying problem of the hydrogel. This work offers a new approach for constructing high-performance and cost-effective pressure sensors. A simple strategy to directly convert chrome shaving collagen fibers into hydrogels with stable surface synapses and abundant pore structures.