Figure 2.

Chemical tuning of the capacitive and faradic parts of the photoresponse. (a) Schematic of the photocurrent measurement system. A patch-clamp electrophysiological recording system was used. Photoelectrodes were placed in the free-standing mode to mimic the behavior in biological media. The pipette was positioned close to the surface of the biointerface. The ITO layer that is in direct contact with the electrolyte was used as the return electrode. (b) Capacitive and faradic parts of the total photocurrent with different EG ratios in the PEDOT:PSS solution (n = 6). (c) Representative photoresponse of the Au/PEDOT:PSS-coated biointerface to define capacitive and faradic parts of the photocurrents. The blue area on the top shows the light illumination period. The blue dashed box marks the region shown in the inset. (d) Negative and positive absolute photocurrent peak ratios with different EG ratios (n = 6). (e) Representative cellular photoresponse generated by the biointerface. The gray dashed box marks the region shown in the inset. (f) Ratio of depolarization and hyperpolarization for different EG ratios (n = 6). All data are presented as means ± standard error of the mean (SEM).