Fig. 3: Performance characterization of sensor units before and after mounting onto curved surface.

A Initial resistance. B Relative resistance changes of sensor unit II before mounting with various force or frequency: (i) force and (ii) frequency. C Relative resistance changes of sensor unit II after mounting with various force or frequency: (i) force and (ii) frequency. D Maximum principal strains of all sensing units and relative changes before and after mounting in initial resistance, hysteresis, and detect deviation. E Step-wave loading response of sensor unit II after mounting. F Cyclic loading of sensor unit II after mounting. G Local enlargement of cyclic loading of sensor unit II after mounting.