|MadSci Network: Chemistry|
This presents a very interesting engineering challenge. If the class were in session now Iíd be tempted to pose it to my engineering design students. I canít think of any set of three fluids that meet all your criteria. You might want to consider a gel for one of the layers, if not all three. Some of the gels used for electrophoresis should be clear enough and are fairly conductive. You should be able to find more information from a biological supplier like Carolina Biological Supply. The gel may also give you a support for wires so that bulbs, motors, and such donít drift about. Whether you use a gel or not there is another issue, corrosion. You might mitigate this some with gold or platinum contacts but that gets us away from being cheap. Even at the 1 or 2 Volts youíd be using across the terminals of the bulb over the one month you mention there would almost certainly be some production of various oxides and hydroxides if not other salts. Some of these will be colored and or opaque and could visually contaminate the area around the wires at the interface between layers. Whether not this detracts or not would be up to the artist. The production of gas bubbles could also interfere with the connection to the conductive layers. There will also likely be the issue that since none of these conductive gels or liquids is as conductive as wire then depending on how far the connection of you power source to the conductive layers is from the connection of the bulb to those layers you may need to provide well in excess of the bulbs required operating voltage to get enough current flow to light it. (If you donít mind the different look you may find LED bulbs are easier to light as they use about one tenth the current of an incandescent bulb.) Just how much more voltage might me needed would probably be a matter or trial and error. As a safety note working with conductive fluids and wet hands can get you a pretty severe (possibly even fatal) shock even with a 6 or 12 Volt car battery. Use your rubber gloves and disconnect power sources. This sounds like fun but do be careful.
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