Mechanical properties of the strain sensor and amplifying circuit. (a) Optical image (top) and FEA strain contour (bottom) of the strain sensor stretched by 150%. (b) Uniaxial stress-strain curves of the strain sensor obtained from experiment and FEA. (c) Optical image (left) and FEA strain contour (right) of the amplifying circuit vertically stretched by 60%. (d) Optical image (top) and FEA strain contour (bottom) of the amplifying circuit horizontally stretched by 60%. (e) Optical images of the amplifying circuit at 0% strain (top), biaxially stretched by 15% (middle), and biaxially stretched by 30% (bottom). The two insets show microscope images of a chip component at undeformed and biaxially stretched by 30% states. (f) FEA simulation model of the amplifying circuit (top), and strain contours of the amplifying circuit biaxially stretched by 15% (middle) and 30% (bottom). (g) The amplifying circuit can be reconfigured to a cylindrical shape (left: top view, middle: side view). FEA simulation gives the strain contour in chip components in the cylindrical shape (right).