by the Defense Advanced Research Projects Agency (DARPA) are developing small, lightweight, easy-to-use MEMS-based biofluidic microprocessors capable of monitoring a person’s blood and interstitial fluid and comparing readings with an assay reference chip. Such devices could not only give early warning of exposure to chemicals or biological agents but also monitor general health, medication usage, and psychological stress.

The coming decade should see other significant advances in medical microsensors. For example, English scientists are developing a camera-in-a-pill that can be swallowed to examine the gastrointestinal tract. The device, currently 11 × 30 millimeters, contains an image sensor, a light-emitting diode, telemetry transmitter, and battery. Several improvements are needed before it can complement or replace current endoscopy tools, including orientation control and a more powerful battery that will enable it to image the entire gastrointestinal tract, from ingestion to elimination. And a Michigan company, a winner in the 2000 Advanced Technology Program competition, is trying to commercialize technologies developed at the University of Michigan. It hopes to create implantable wireless, batteryless pressure sensors to continuously monitor fluids in the body. Potential beneficiaries include patients with glaucoma, hydrocephalus, chronic heart disease, or urinary incontinence.

Artificial or electronic noses are starting to find a home in industry. These devices typically consist of an array of polymers that react with specific odors and a pattern-recognition system to identify an odor by the change it produces in a polymer. To date, artificial noses have been used mainly in the food industry to augment or replace existing means of quality control, but potential uses include quality control in the pharmaceutical, cosmetic, and fragrance industries. Expanding the uses of electronic noses will require sensors with greater sensitivity and specificity and more advanced algorithms to improve performance.

Photonics

Photonics underpins optical communications. Because photons are more effective carriers of information than electrons, the demand for new ways to harness light to communicate and store data will intensify, driven by the worldwide need for greater bandwidth. The development of wavelength division multiplexing has opened a progressive revolution in data transmission, storage, and processing that could match that of electronics in the 20th century. Although most photonic circuits today are analog, the development of low-cost photonic integrated systems will enable uses beyond communications, including signal processing and exquisite sensors.

Photons travel at the speed of light and do not interact with one another, which all but eliminates cross talk and inference. However, logic functions require some interaction, and researchers have sought ways to process information electronically and transmit it optically. One promising approach to integration is



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