Inspired by the microstructure of rod cell, a bacteriorhodopsin/alumina nanochannel hybrid system is demonstrated that converts flickering light impulses below 130 Hz into distinguishable patterns of photocurrent to mimic frequency-responsive characteristic of mammalian retina in vitro. An optimal response frequency is identified with unique dependency on bacteriorhodopsin thickness rather than the proton concentration gradient and pore size of the alumina nanochannel.