Seminario: "Electrochemistry of Stimulating Electrodes Implications for Front-End System Design of Implantable Neurostimulators"

Electrical current in a metal is carried by electron flow while in tissue is carried by ion migration. At the electrode/electrolyte interface a conversion between charge carriers may occur during stimulation. Designing safe and more efficient implantable neurostimulators require basic understanding and consideration of electrochemical aspects that take place on the stimulating electrodes. Classical circuit design approaches, such as equal charge balancing schemes, may force electrode potentials into regions where tissue may get damaged or electrodes corroded. This is because the charge balancing pulse always overcompensates in returning the electrode potential to its pre-pulse level given the double-layer charge gets re-distributed during the interphase period and asymmetries in the electrochemical situations under each waveform phase are also present.
This talk will walk through key aspects in neurostimulator front-end system design from an industry perspective, utilizing Spinal Cord Stimulation as a use case but without losing generality, covering the aspects mentioned above. The talk will highlight irreversibility is actually achieved during transitory stimulation but the use of DC blocking capacitors enables the sliding of the cathode and anode potentials (within the water window) to accommodate the required charge injection maintaining safe excursions in steady state. The talk also highlights the importance of properly modelling the double-layer as a fractional pole capacitor to simulate accumulated charges during stimulation utilizing Spice-like simulators.
Co-sponsored by: Grupo de Microelectrónica, Facultad de Ingeniería, Universidad de la República
Speaker(s): Marcelo Barú,
Room: 502-Azul, Bldg: Facultad de Ingeniería, Julio Herrera y Reissig 565, Montevideo, Montevideo, Uruguay