Multi-Channel Surface Electromyograph for Monitoring Intradialytic Cramp

Abstract

This paper presents the design and construction of a multi-channel surface electromyograph for monitoring intra-dialytic cramp to help medical staffs in the care of patients on hemodialysis. The developed system consists of two main parts: EMG circuits, and a processing circuit. The EMG circuit detects the myoelectric signal from the surface electrodes placed on the skin over the muscle, or the sEMG signal ($S_{EMG}$), and process the detected $S_{EMG}$ to obtain a signal of which the amplitude represents the peak amplitude of the $s$ EMG signal ($V_{EMG}$). Each EMG circuit is composed of a biopotential amplifier, a bandpass filter, a full-wave rectifier, a peak detector, and a low-pass filter. The processing circuit acquires the $V_{EMG}$ data from the EMG circuits, and provides the alarm if the $V_{EMG}$ increases higher than the level of the reference voltage ($V_{ref}$) set by the user. The experiments were held by making the measurement at the gastrocnemius muscle and performing the voluntary muscle contraction to imitate the muscle cramp. The results showed that the EMG circuits can effectively detect and process the $S_{EMG}$ in order to provide the $V_{EMG}$ in response to the muscle contraction, and the processing unit can provide the alarm correctly when the gastrocnemius muscles are contracted.