Fig. 4

Simultaneous measurement of respiration and ECG of the volunteers at resting state and after exercise. a A demonstration of a flexible device adhered to the surface of chest skin. The enlarged figure for showing our device with good adhesion and transparency. b ECG obtained by carbon fiber (CF for short) with nano-copper and bare carbon fiber. The ECG signals were also obtained before and after jumping 50 times. c Statistics of signal-to-noise ratio for comparing the quality of the signals obtained by carbon fiber with nano-copper and bare carbon fiber. Results showed there is a significant difference in signals obtained by carbon fiber with-nano-copper and bare carbon fiber. *P-value < 0.05. d Point-care plot for showing the beating period change before and after exercise. e Respiratory signals obtained by carbon fiber with nano-copper and bare carbon fiber. The signals were also observed before and after exercise. f, g Fourier transform for showing the energy distribution before and after exercise. The blue curve represents the distribution of bare carbon fiber, the red curve represents the distribution of carbon fiber with nano-copper. h, i Box charts for showing the change in respiratory frequency and respiratory stress before and after exercise