The first bio-electronic material bacteriorhodopsin

When bR is hit by a photon, it changes its structure (and its color) and pumps a proton across the bacterial membrane, thus generating a potential which supplies the cell with energy. Under certain conditions it can be stable up to 140 C. It can run through its cycle of optical switching about ten million times and thus outperform virtually all man-made photochromic materials. 

After the remarkable properties of the purple membrane were discovered by W. Stoeckenius and D. Oesterhelt in the early 1970s, Soviet scientists were the first to investigate its potential for computing. By using bioelectronics, they hoped to compensate for the headstart which Western scientists had in semiconductor technology. Although part of the research carried out as the Project Rhodopsin in the Soviet Union is still kept as a military secret, it is known that the Soviets developed a bR-based microfiche film called Biochrome. 

More generally, bacteriorhodopsin was regarded as an interesting biological material in search of an application, and dozens of suggestions and claims were made during the 80s, as reviewed, for instance, by Oesterhelt and coworkers (1991). 

Somewhat ironically, its performance was disappointing in the field which corresponds to its natural task in halobacteria, namely converting sunlight to energy. For instance, if it were to be used to generate electricity from light, the predicted efficiency of ca. 1% would not be able to compete with standard photovoltaic cells reaching up to 14%. 

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