Fig. 4: Sensing performances.
a, Normalized resistance change (ΔR/R0) of the CCAP hydrogel versus pressure in air and water. b, ΔR/R0 during five compression cycles at different strains in air. c, ΔR/R0 at 50% strain during 1,000 compression cycles in air. d, Schematic illustrations of the cumulative deformation and structural recovery under sliding motion in the x direction. Δl and Δh are the instantaneous tensile deformation and compressive deformation, respectively, during the sliding. e, Schematic illustrations showing resistance change dependent on the cumulative tensile strain in the x direction and compressive deformation when pressing the hydrogel. Positions 1 and 2 are selected to show structural evolution before and after the pressing. l and h are the transverse and vertical dimensions at position 1. f,g, ΔR/R0 in response to sliding on the CCAP surface at different velocities in the x (f) and y (g) directions. The green and blue dotted lines show the beginning and the end of the movements on the hydrogel surface. h, ΔR/R0 when pressing the CCAP surface to different depths with a glass rod. i, ΔR/R0 versus strain during cyclic compression in water. j, ΔR/R0 in response to bending and relaxing cycles of a finger in water at various bending angles. The inset images show the monitoring of the finger motion in water. k, ΔR/R0 in response to gradual finger bending in water from 0° to 90° and relaxing to 0°.
