fig1

Figure 1. Flexible, ultrathin, skin-integrated and Au-based strain sensor. (A) Schematic of strain sensor. (B) Optical image of patterned Au/Cr electrode design. (C) Optical image of strain sensor mounted on the human epidermal surface. (D) Finite element analysis of strain distribution on strain sensor under stretching, twisting and bending. (E) Optical image of strain sensor attached on a pink PDMS surface with three mechanical deformations, including bending, stretching and twisting.