Fig. 4: Electrochemical Properties of µECoG Array.

a Schematic of inkjet printed PEDOT:PSS on the ultrathin Au based transparent µECoG array. b Optical image of the PEDOT:PSS inkjet patterned ultrathin Au µECoG array (Scale bar: 100 µm). c Transmittance spectrum of PEDOT:PSS printed transparent µECoG array (500 nm: average thickness, 900 nm: peak thickness). Inset images show representative samples of the two different regions. And the 473 nm (blue) and 580 nm (amber) wavelength ranges used for optogenetics modulation are displayed. d Magnitude of Bode plots of representative EIS data. The thickness of PEDOT:PSS reported as the averaged value. e AFM scanning results of Au/Ti (50 nm/5 nm) (left) and 8 nm Au/(EDTA/PSS) (right) film (Scale bar : 200 nm). f Phase angle in the Bode plots of the representative EIS. g Cyclic voltammetry results of 500 nm PEDOT:PSS/8 nm Au/(EDTA/PSS) µECoG array at various voltage scan rates. h Charge storage capacity of µECoG arrays at various voltage scan rates. i Long-term stability of µECoG array in PBS immersed environment (Totally 4 weeks, 37 °C) j Comparison of area-normalized electrochemical impedance and RMS noise among recently developed transparent/opaque microelectrodes for neural recording. (Minimum noise detection level of Intan recording: 2.4 µV).