Fig. 4
From: A Portable Triboelectric Nanogenerator for Real-Time Respiration Monitoring
Mechanical tests on the TENG based respiration sensor. a Photograph of the TENG sensor fixed to the stretching machine. b The output voltage signals of the sensor under an excitation in trapezoidal form and the corresponding time histories of the sliding displacement and force. c The time histories of output voltage of the sensor with different displacement amplitudes. d The peak values of the output voltage and the traction force as functions of the maximum sliding displacement