Decomposition and multi-scale analysis of surface electromyographic signal for finger movements

Decomposition of the surface electromyography (sEMG) signal is vital for separating the composite, complex, noisy signals recorded from muscles into their integral motor unit action potentials (MUAPs). By precisely identifying each motor unit’s activity, this method offers greater insights into the functioning of the neuromuscular system, which helps isolate each motor unit's contribution, making it essential for understanding muscle coordination and diagnosing neuromuscular disorders. In this study, we employ the maximal overlapping discrete wavelet transform (MODWT), which is well-suited for analyzing signals in the time-frequency domain. The study decomposed the sEMG signal into six levels to identify the neural activity of finger movements and analyzed the motor unit action potential (MUAP). In the frequency range of 30.2 and 64.6 Hz, the signal exhibits the highest MUAP which is independent of movement. Using inverse MODWT, it was rebuilt from the decomposed levels. With 95.8% accuracy, the similarity between the reassembled signal and the original signal was determined using correlation analysis to assess the efficacy of the method.