Collagen fibers from chrome shavings for an ionic capacitive pressure sensor

Currently, flexible capacitive pressure sensors (CPSs) with excellent performances are highly desired in the field of wearable electronics. Raw material selection, rational structure design and simple preparation method are both worth considering. In this work, a simple strategy to construct flexible ionic fiber CPSs based on chrome shavings is proposed. Ionic donor, water-soluble ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate [EMIM][OTF] mixed with the fully swollen chrome shavings collagen fibers (CFs) to obtain the ionic fiber via drying. Chrome shavings CFs support rough surfaces and porous structures, ionic liquids provide ionic conductive sensing properties. The prepared ionic fiber displays outstanding sensing performances due to the synergistic effect of flexible fibrous matrix and ionic donor. The optimized ionic fiber CPS exhibits high sensitivities of 5.37 kPa-1 (0-1.2 kPa), 1.7 kPa-1 (1.2-7 kPa), 0.95 kPa-1 (7-15.8 kPa) and achieves the recognition of human activity signals. Meanwhile, the sensor displays outstanding environmental adaptability and the application potential in the field of temperature sensing. This work offers a new approach for preparing high-performance and cost-effective fiber-based CPSs, as well as the resource utilization and high-value utilization of chrome shaving CFs.