Lane is deputy division leader for the Laboratory's Medical Physics and Biophysics Division and Grant's former colleague. "Livermore offers excellent research grant opportunities, especially for younger researchers. Sheila was involved in a number of those collaborative projects, notably a glucose sensor project. She's very talented," he says, "and we miss her."

She misses them too. "I was at Livermore for four years and had a chance to develop a variety of sensors -- optical base, chemical base, and electrochemical. These sensors did everything from looking at the gases coming from stock-piled nuclear weapons to developing different ways of detecting glucose levels in diabetics," she says.

An Iowa native, Grant left Livermore only because she wanted to live closer to home. She first accepted a faculty position at Michigan Technological University, then came to MU three years ago.

At MU, Grant's focus has been on chemical sensors, specifically optical base sensors. These are characterized chiefly by their use of a tiny glass fiber probe equipped with an element, called a biorecognition element, that interacts with the virus or organism being detected.

This biorecognition element, Grant explains, can be an enzyme, antibody, or bacteria that, when introduced into the body, will bind or react to the substance being analyzed (the "analyte"). These reactions take place at a miniscule scale and are visible only with a microscope. Changes are typically detected by labeling the biorecognition elements with fluorescent dyes which, after interacting with the analyte, are converted into a detectable signal.

Biosensors have two jobs: they must recognize a specific biological event -- such as a change in a diabetic's glucose level, or the viral activity of someone with HIV-- and they must convert that event into a useful signal that people can read. The promise of biosensor technology is that one day this will happen accurately, inexpensively, and on the spot with unobtrusive and easy-to-use devices.

"A sensor is basically a sensor no matter what you're trying to detect. A person can use the same sensor design, but by changing the biological agents, that is, the antibodies, peptides or whole cells, different analytes can be detected," explains Grant.

"We take an optical fiber, which is a glass fiber, and immobilize our biological sensing agents onto the surface tip of that fiber. To that agent we add fluorescent dyes. Here comes your antigen -- whatever it is we're trying to sense--Troponin-T, for example, which is an early marker of heart attacks, and it interacts with our immobilized sensing agents. When it interacts, the dye changes its fluorescence and we capture this light."

The technique Grant refers to is called Fluorescence Resonance Energy Transfer, or FRET. It involves the use of different dyes to mark different antibodies. Grant says she has the option of using several available pairs of dyes. Choosing which ones will work best with which antibodies is often the first step when designing a sensor.

Once the antibody encounters what it is "looking" for and the fluorescence changes, the light travels through the fiber and is read by photo multiplying tubes, converted into an electrical measurement, and interfaced with a computer. The results are hard numbers that researchers, doctors and, ultimately, patients, can use. "It's a bench-top system right now, but what's exciting is that I'm also working with a group of people who are researching ways to miniaturize these devices," she says.