Conducting Polymers in Augmenting the Properties of Biopotential Electrodes

Conducting polymers, especially Polypyrrole (PPy), have been extensively used for the modification of the electrode surface by electrochemical deposition. The combination of carbon nanotubes (CNTs) and PPy has also been successfully electrodeposited on the electrode surface to lower the impedance. The morphology of such coated electrode were also found to be rougher than PPy or CNT alone which could indicate greater electroactive area of the coated film. The thesis is based on electrodeposition of two types of biopotential electrodes: a) Microelectrode arrays (MEAs) and b) Macroelectrodes. The electrodeposition process was evaluated by chronopotentiometric measurement by measuring the charge and current density. The PPy and PPy/CNT solutions were successfully electrodeposited onto the Platinum(Pt) macroelectrode surface. PPy/CNT decreased the macroelectrode impedance. Optical Profilometer analysis showed that PPy-CNT 0.25 sample (made from 0.25mg/ml of CNT) produced the roughest surface and PPy-Control sample produced the smoothest surface. Atomic Force Microscopy(AFM) analysis showed that the PPy-CNT 0.5 sample (made from 0.5mg/ml of CNT) was more rougher than the PPy surface. Micrograph analysis showed thick coating with PPy-CNT 0.25 and PPy-CNT 0.5 samples than PPy-Control and PPy-CNT 0.1 (made from 0.1mg/ml of CNT) samples. A wide range of electrical properties were also observed in different frequencies. PPy-CNT 0.5 was highly resistive at 1kHz with phase angle of 29° and most capacitive at 1.0Hz with phase angle of -68°compared to coated electrodes. PPy-CNT 0.25 showed maximum impedance magnitude at 1.0Hz and PPy-CNT 0.5 showed least magnitude at 1KHz. Bare Pt was highly capacitive at 1Hz with the phase angle of -78°. PPy-CNT 0.5 was highly capacitive at lower frequencies (