A comparative study of EMGdi recording electrodes

Electromyographic recording of the diaphragm have been used to evaluate its functionality and its fatigue. This signal is contaminated by the electrical activity of the heart, movement of diaphragm and lung volume change. Conventional recording of EMG_di signal can be achieved in two main ways:(i) insertion of needle electrode in the diaphragm with the risk of lung perforation, and (ii) using an array of electrodes built in a catheter that can be inserted in the oesophageal conduit and centered in the gastro-oesophageal sphincter. Usually ECG signal overlaps EMG_di signal in a large band of its spectrum. Several methods were proposed in order to eliminate the ECG signals such as high pass and LMS adaptive filters. In this project we model and simulate the functionality of two types of recording electrodes, and to verify the effect of artefacts on EMG_di signal. The model consists of (i) 3D block filled with air with zero potential at its boundaries, (ii) a point source of fixed potential and variable position, and (iii) an array of electrodes. The potential distribution on the electrodes was obtained by solving Laplace equation using finite element method. Our simulation results on examined types of electrode geometries showed a reduction of interference signals generated by the ECG and other EMG muscles on the EMG_di when ring electrodes were used. More complex geometries are currently under investigation in order to explore the reduction of contamination.