Fig. 4: Quantitative sensing by the EEN for rehabilitation.

a Electrodes of the EEN during the concentric contraction of the biceps. b Frequency spectra of the EMG signals of the EEN and commercial electrodes. c Comparison of the EMG signals during dynamic contraction (upper) and isometric contraction (down) of the EEN and commercial electrodes. d Illustration of maintaining the contraction of the biceps with dumbbells. e sEMG signals of the biceps during tasks with different muscle loadings (1–7 kg). f RMS of the sEMG signals collected under different weight loadings. g EEN positions for spine monitoring. h, i Recording signals of spine bending for two samples. j Heatmap of spine bending monitoring. k Signals of the shoulder joint under different tasks for rehabilitation evaluation. l Quantified evaluation for the sprain of the ankle joint