Unusual Copper Oxide Thermopile

Nyle Steiner of SparkBangBuzz never fails to impress with his old-fashioned hand-on approach to electronics.  Whether he’s improvising memristors from bits of junk he picked up off the ground, building audio oscillators using blobs of zinc instead of transistors or tubes, or whipping up an atmospheric-nitrogen laser using a few scraps of aluminum and a power supply, Nyle’s projects always serve to remind me that electronics is about much, much more than just soldering together components that came out of a factory somewhere.

This project is no exception.  Most people think of a thermocouple as a junction of two dissimilar metals.  In fact, the only metal in the thermocouples that make up Nyle’s small, radial thermoelectric generator is copper, strategically oxidized in places to form a layer of CuO that provides the necessary dielectric junction.  Nyle writes:

I have spent my entire life reading whatever technical books and articles I could find and can recall seeing only one book that tells how to make something like this and none that explain how this device works…Touching the two oxidized wires together forms a junction of copper oxide to copper oxide. This is not where the action is. The copper oxide on both wires should be thought of as one solid conductor between the two copper wires – a very short one at that. This can now be seen as the classic two thermocouples back to back circuit. We have a copper – copper oxide junction on the hot wire and an opposing copper oxide – copper junction on the cold wire…It is easy to wonder how this device could work at all because of the copper oxide, that is between the two wires, being almost an insulator. Copper oxide however, also acts like a thermistor with a very high negative temperature coefficient. Even the “cold” wire still gets hot enough that the resistance of the copper oxide drops relatively to a very low value – enabling current to flow.

See all our past coverage of Nyle’s work here. [Thanks, Eric!]

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I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

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