Optical Stimulation Effects on TiO2 Sensor Dielectric Used in Capacitively-Coupled High-Density CMOS Microelectrode Array

The effect of optical stimulation of neural tissue is considered in capacitively coupled CMOS microelectrode arrays used for
in vitro
extracellular recording from neural tissue. Using a 25-nm high-k TiO
₂
sensor dielectric with 20% ZrO
₂
, light-induced currents through the dielectric are found at short wavelengths within the visible and relevant spectrum for the above-mentioned purpose. Purely capacitive behavior is obtained for green light and longer wavelength, leakage-induced artifacts at shorter wavelengths are avoided by using optimized operating conditions of recording sites and entire system.