fig3

Figure 3. Electrical signals of flexible strain sensor under different external stimuli. (A) Optical image of strain sensor mounted on the back of a hand and its enlarged optical image of the strain sensor during deformation. (B) Electrical signals (∆R/R₀) of strain sensor under different finger bending angles. (C) Optical image of strain sensor mounted on a wrist for human pulse rate detection and its electrical diagram. (D) Electrical signals (V) of strain sensor in the pulse rate test in (C). (E) Optical image of strain sensor mounted on a waist for ankle for walking motion detection. (F) Electrical signals (∆R/R₀) of strain sensor under the walking motion test.