In vitro and in vivo study of temperature increases in the brain due to a neural implant

A chronically implantable, wireless neural interface device requires integrating electronic circuitry with the interfacing microelectrodes in order to eliminate wired connections. Since the integrated circuit (IC) dissipates a certain amount of power, it will raise the temperature in surrounding tissues where it is implanted. In this paper, the thermal influence of the integrated 3-dimensional Utah electrode array (UEA) device implanted in the brain was investigated by experimental measurement in vitro as well as in vivo. The maximum temperature increase due to the integrated UEA system was measured to be 0.067 degC/mW for in vitro and 0.050 degC/mW for in vivo conditions. Lower temperature increases of in vivo measurement are due to convection through the blood perfusion presenting in the living tissues.