There is a clear trend towards embedding of electronics everywhere (toys are a clear example, over 80% of them have some sort of electronics inside), including in our body. Just yesterday I mentioned the possibility of embedding electronics in a patch that can be glued on our skin, and in the past I reported on smart pills embedding electronics for a variety of purposes (from monitoring to releasing specific substances in specific environment or at specific times).
Today it is about a research carried out at Iowa State University that has found a way to create what why call "transient electronics" a set of electronic components that once have been used dissolves in the ambient, including the human body.
They have managed to create a special polymer composite that can be given a trigger to dissolve. It can be used as a temporary monitor inside our body, as an ambient sensor that can be washed away by rain once its job is done and, of course, as a military device that once used simply disappears.
The composite is a mixture of a gelatine with sucrose and a polyvinyl alcohol. By varying the percentage of gelatine/sucrose one can delay the dissolution.
Within this substance one can include resistors and capacitors. As we know transistors are so tiny that it is not really a problem to include them and having them disappearing once the polymer substrate dissolves. The researchers are working to be able to include also LED that can dissolve as well.
In perspective the researchers point out that there might be several areas where a transient electronics. Imagine using this type of material for credit cards. If you are losing the card (or it gets stolen) you can send a signal so that at the first attempt to use it receives the signal to dissolve!
Another example might be a transmitter programmed to work for a certain time or within a certain temperature range. You place it in a food package and when you buy the package you check for the signal. If it is not there it means that the food may no longer be good!