Strap yourself in for the next wave of smart devices: jewelry that emits aromas to match your mood, televisions that give off a cheese smell during a pizza commercial, and pills and implants that dispense drugs in carefully measured doses.
An experimental microchip from the Massachusetts Institute of Technology in Cambridge promises all that and more. The new chip is the first silicon semiconductor to be able to store and release a variety of different chemicals in precise amounts at specific times from tiny, built-in reservoirs. And it has no moving parts: the chemicals are released when a small electric current dissolves a thin gold cap covering each reservoir. Future versions might be made of new, biodegradable materials with biosensors.
"The applications are almost unlimited," said Robert Langer, co-developer of the chip and professor of chemical and biomedical engineering at MIT. "The chips can be made larger or smaller. They can have all kinds of chemicals in them. And they can be integrated with microprocessors to make them smart."
Professor Langer, Michael Cima, a ceramic processing professor at MIT, and John Santini, a chemical engineering graduate student at MIT, spent five years developing the chip. Their research, funded in part by the National Science Foundation, appears in today's issue of Nature.
The first products using MIT's controlled-release chemical microchip technology could appear in a few years, Langer says. The manufacturing technology already exists, but the chip is only in prototype form now. It needs to be improved and refined for particular applications.
Langer and his colleagues become animated when they talk about future uses of the chip, spouting a new application with each sentence. They envision more life-like entertainment systems that can unleash an almost unprecedented assault on the senses.
Imagine a movie theater screen that sprays pine scent during a nature film to complement the stereo surround-sound crackling of brush in the forest and the digital video variations of green in fir tree branches. New cars will waft lemon to enliven stale air. And chemists will use hand-held probes with reagent-laden chips for medical diagnostics or detection of polluting chemicals.
Graduate student Santini said other scientists are experimenting with a similar idea: integrating smell into virtual-reality goggles via tubes carrying scents.