Influence of Electrode Surface Area on the Fractal Dimensions of Electrogastrograms and Fractal Analysis of Normal and Abnormal Digestion Process

Abstract

Electrogastrogram (EGG) signals are electrical signals generated by stomach muscles and these signals are used to perform diagnoses of digestive disorders. For the non-invasive measurement of EGG signals, the surface electrodes are positioned on the stomach and the physical properties of these electrodes, play an important role. In this work, the changes in electrode contact area of surface electrodes and its effects on the fractal dimension of the recorded EGG signals has been analyzed. Three different fractal dimensions such as Maragos Fractal Dimension (MFD), Rescaled Range Fractal Dimension (R/S FD) and Spectral Fractal Dimension (SFD) were computed to investigate the effect of two different surface electrodes with contact diameter of 16 mm and 19 mm on the fractal quality of EGG recordings. Further, the normal and abnormal EGG signals such as the signals measured from diarrhea, vomiting and stomach ulcer patients were analyzed using the fractal measures. Results demonstrate that the average values of MFD, R/S FD and SFD of the electrogastrograms is high in the case of the surface electrodes with higher contact diameter. Further, it is demonstrated that there are significant variations in the fractal dimensions of normal and abnormal EGG signals.