Figure 5. Characterization of piezoelectric properties of P-iskin. a) Schematic diagram of ion piezoelectric effect. b) Schematic of PFM test. c) Shape graph of AFM test including test points. d) Graphs of voltage versus phase and voltage versus amplitude after applying bias voltages to the sample for forward voltage (-5 V) and reverse voltage (+5 V). e) Characterization of piezoelectric properties using a customized force-electric test system. f) P-iskin for injured arm motion monitoring. g) P-iskin for healthy arm motion monitoring.