IV.35 - Protein Diodes?

Luca Turin (l.turin@ucl.ac.uk) at University College in London writes:

Proteins have been suspected of being semiconductors for some time, but the difficulty has always been to make a monolayer of protein on an atomically smooth metal surface and contact it with a second smooth surface to avoid direct metal-metal contact. While doing some polarographic experiments on proteins using a dropping mercury electrode, I noticed that the droplets of mercury coated with protein would not coalesce as they normally do. This suggested a means of making a metal-protein-metal device by pushing together two drops of mercury in a tube separated by an aqueous solution of protein. As such, the device is symmetric and behaves like two diodes in series connected in opposite polarity. However, if some zinc is dissolved in one of the mercury droplets to make zinc amalgam (and thereby change its work function) the device behaves like a respectable diode, stable for hours at room temperature. I do not foresee IC's or power rectifiers made with egg white in the foreseeable future, but to paraphrase Dr Johnson the amazing thing is "not that it does it well, but that it does it at all !".

More details can be found in a directly related patent at the IBM Patent Server: http://patent.womplex.ibm.com/details?patent_number=5258627