The idea of a circuit board that dissolves the moment it is cooled totally sounds like something out of the Mission: Impossible movies, or maybe a mystery heist flick where a rare computer disappears after being removed from its air-conditioned safe.
In fact, it sums up the work being done by researchers at Vanderbilt University, described in a new paper published in the journal ACS Applied Materials and Interfaces. What they have been working on is a way of building transient electronics that come apart when you stop heating them.
“What we have done is produce a composite system that behaves like a regular circuit board when immersed in warm water, but if the water cools below a threshold temperature, the entire system disintegrates, dissolves, and stops working,” Dr. Leon Bellan, assistant professor of mechanical and biomedical engineering at Vanderbilt, told Digital Trends. “We have achieved this behavior by coupling two separate materials: networks of silver nanowires, and a polymer that exhibits the odd behavior of being insoluble in warm water, but soluble in cold water.”
These nanowires are embedded in the polymer, which holds the network together so that they are touching one another and therefore produce a path to conduct electricity. Should the polymer dissolve, there is nothing to hold the nanowires together. As a result, the network falls apart, the nanowires do the same, and the conductive path is lost as the entire system disintegrates.
So far, so intriguing. But why on earth would you want a dissolving circuit board? As suggested earlier, secretive operations could be a legitimate use. The heat supply could be a battery powering a heater, or even the body temperature of a soldier on whose body a top-secret circuit has been implanted. If the battery is lost, or the body heat is no longer available, the circuit vanishes.
“Some possible applications that are less in the realm of James Bond would [also] be tracking tags (RFID) implanted in hospital patients,” Bellan said. “These could be triggered to disintegrate and stop functioning by local application of a cooling stimulus, such as ice, instead of requiring surgery to remove them.”
We guess the second one makes good sense. We still dig the Mission: Impossible one the most, though!
