Interesting item from John Rogers and co-workers at the University of Illinois Urbana-Champaign, as reported in AAAS ScienceNow:
The new technology is the product of advances in several areas. One is in the active circuit components—transistors, diodes, and other inherently stiff semiconductors—which Rogers’s group has flattened and shrunk to the size of the tiniest bumps and wrinkles on the skin. Another is in the material on which these components are arranged: a sheet of rubbery “elastomer” that mimics the mass, thickness, and elasticity of the skin. Like an extra-clingy plastic wrap, the elastomer sticks to the skin naturally, using only the weak, short-range, attractive forces that always exist between neighboring molecules for adhesion. It can stay attached for over 24 hours almost anywhere on the body.
The full paper is behind Science‘s paywall, but it looks like the circuit is applied to a sheet of BASF’s Ecoflex biodegradable polymer film which, like a common temporary tattoo, is backed with glue. The circuit is applied with water which dissolves the glue and leaves the polymer-bound circuit closely bonded to the skin. [Thanks, Alan Dove!]
Update:Though the paper requires subscription, the supporting information (including some telling fabrication procedures) is freely available. The circuit itself is produced by more-or-less conventional photolithography (with some novel geometry to maximize flexibility), then transfer-printed onto the glue-backed Ecoflex I mentioned above.