"To make the devices, silicon transistors about one millimeter long and 250 nanometers thick are collected on a stamp and then transferred to the surface of a thin film of silk. The silk holds each device in place, even after the array is implanted in an animal and wetted with saline, causing it to conform to the tissue surface. In a paper published in the journal Applied Physics Letters, the researchers report that these devices can be implanted in animals with no adverse effects. And the performance of the transistors on silk inside the body doesn’t suffer. [...] The biocompatibility of silicon is not as well established as that of silk, though all studies so far have shown the material to be safe. It seems to depend on the size and shape of the silicon pieces, so the group is working to minimize them. These devices also require electrical connections of gold and titanium, which are biocompatible but not biodegradable. Rogers is developing biodegradable electrical contacts so that all that would remain is the silicon." - Steven Perez from Bookmarklet