Multichannel EMG signal acquisition system using dry-type grooved electrodes

Abstract

With the growing interest in field of bio signal applications, it has become increasingly important to focus on improved signal acquisition mechanisms. The increase of research in EMG measurement techniques puts emphasis on bio signal detection materials and surface designs that come in contact with the skin. The work presented in this thesis focuses on how the shape of the electrode surface which comes in contact with the skin acts to improve not only the EMG signal, but also the electrode skin impedance as well. This thesis document studies EMG detection surface developed by fine machining of solid silver to produce a millimeter scale grooved electrode and plastic coated with pure silver for EMG signal acquisition. The grooved electrode surface consists of a higher surface area as compared to its flatter counterpart. The surface was built to not only improve the contact with skin, but also to improve signal quality. A detailed comparison of the silver machined electrodes with gelled type EMG electrodes and a silver surface of same dimensions but with a flatter surface are also provided. A comprehensive account of the comparisons suggest that the results from the proposed electrode surface are close to gelled EMG electrodes and are better than the flat silver surface. After detailed testing of all the electrodes, that is the solid silver grooved and silver coated electrodes, they were expanded to a multi-channel signal acquisition system. After developing a comprehensive analog and digital signal processing scheme for the acquired EMG signal, this multichannel system was then successfully used to drive the fingers of a robotic arm. Thus, the application of the newly built electrodes was effectively tested for robotic prosthesis.