Cortical recording with conducting polymer electrodes

Abstract

The ability to record from the same neuron for extended periods of time is essential to understanding how the brain reorganizes during motor learning. Conventional chronic recording microelectrodes are made from metal or silicon. However, the large stiffness mismatch between the electrodes and brain tissue causes shear-induced inflammation, limiting long-term recording stability. The flexibility of a polypyrrole microwire has the potential to improve the chronic recording stability by minimizing the stiffness mismatch. This thesis shows the fabrication of conducting polymer electrodes and the stability of their impedance in physiological saline. The initial impedance was as low as 70 k[omega], but the electrode impedance increased by a factor of 10 when immersed in saline over 370 hours. This conducting polymer microwire electrode was implanted in a rodent brain and successfully used to record neuronal action potentials.