Wearable Chemical Sensors May Soon Be Available

Aug. 16, 2001 -- New research involving liquid crystal technology similar to that used in digital watches and laptop computers may soon help you determine if the meat you buy is fresh or whether your kids are exposed to pesticides while playing in the garden.

The technology, developed by researchers at the University of Wisconsin, should allow the development of inexpensive personal sensors, which can be worn like badges to detect real-time exposure to certain chemical agents.

The findings were reported in the Aug. 17 issue of the journal Science. In a separate report, Harvard University researchers detailed the development of personal sensors designed to radically simplify the detection of certain cancer markers. Pending FDA approval, the medical advance could be commercially available within the decade.

Although techniques to detect chemical exposures already exist, they are too bulky and complex for personal use. In addition to measuring immediate exposure to certain synthetic organic chemicals, the sensors developed by University of Wisconsin researchers Nicholas L. Abbott, PhD, and Rahul R. Shah, can be designed to measure cumulative exposure over time.

"The badge could be worn by children or even agricultural workers to measure personal exposure to pesticides," Abbott tells WebMD.

"There are also potential applications for the Department of Defense in terms of chemical exposure," he says. "One of the problems the army has is keeping track of the useful life of protective clothing. With this they can easily tell, for example, if a protective mask is halfway through its useful life."

The sensors could also be used in food packaging, Abbott says, to monitor chemical markers of food spoilage. And the technology may one day allow simple detection of toxic nerve gases like sarin, the deadly, odorless gas that has been used by terrorists and in warfare. Badges incorporating the sensor technology should cost less than a dollar to produce.

The sensors consist of an ultrathin gold film with nanoscale corrugation. The surface of the gold film is dotted with chemical receptors that weakly anchor liquid crystal along the film's surface. Researcher Charles M. Lieber, PhD, and colleagues at Harvard used nanowire technology to develop chemical and biological sensors with the potential to detect a single protein molecule or piece of DNA.

"If you imagine a hair from your head next to a redwood tree, that is what a nanowire looks like next to your hair," Lieber tells WebMD. "They are incredibly tiny."

Lieber says the tiny sensors could lead to the first simple, immediate diagnostic test for protein markers of certain cancers, and may also simplify the screening of experimental drugs.

"One of the biggest problems with cancer recurrence is that right now people are tested every six months or every year, and if a tumor is found it might be too late," Lieber says. "There are proteins associated with certain cancers, like breast cancer and prostate cancer, but the tests for these proteins currently involve a lot of biology. This would be a real-time detector of these cancer markers."