The Eyes Tell All

A holographic contact lens sees trouble brewing inside the body

Kaleidoscopic holograms like the ones stamped on your credit cards could soon wind up in the eyes of diabetics. Researchers at Smart Holograms in Cambridge, England, have devised a contact lens that changes shape in response to glucose found in tears--a direct indicator of blood sugar. To find out whether it´s time for an insulin shot, the wearer would simply snap a picture of his eye with a handheld infrared camera that would then analyze changes in the hologram and display the results.

Since nearly half of all diabetics wear contacts, the hologram lens--set to enter clinical trials next year--could be a convenient, painless alternative to traditional finger-prick tests. Early results show that it´s at least 50 percent more accurate.

The lens contains your basic hologram: a clear, 10-micron-thick polymer film imprinted with a layer of dots that reflect light. What gives the hologram its sensitivity, and sets it apart from typical holograms, is a coat of synthetic receptors that bind to sugar molecules. The reaction causes the hologram to absorb water and swell (imperceptibly to the wearer), changing the length of the light waves reflected off the patterned film.

Also in the works is a portable iPod-shaped device that uses shape-shifting holograms to detect microbes such as anthrax and smallpox.