A Wireless Implant for Diabetics
July 27, 2004 -- For people with advanced cases of diabetes, monitoring the levels of glucose in their blood is a routine hassle of needles and electronic measuring devices. But soon, diabetics may be able to wave it all goodbye. Literally.
Researchers at Penn State University have been working on developing a tiny sensor that could be implanted under a patient's skin to monitor the blood's chemistry and wirelessly report back its findings.
And as reported in a recent issue of Analytical Chemistry, Craig Grimes, a professor of electrical engineering and his team took a unique approach to developing this new sensor.
Grimes says the basic research began about four years ago as he thought about how to create a sensor that would work without requiring a power source or a physical connection with monitoring equipment. And the answer, he says, was in the technology most consumers are familiar with at retail stores: those tiny anti-theft tags hidden in merchandise.
"I was thinking about how those anti-theft markers work," says Grimes. "Effectively what you have there is a passive sensor that costs about next to nothing to produce, yet can be monitored over a large area."
Specifically, the markers — or "magnetoelastic tags" — are thin ribbons of plastic that vibrate when passed through a magnetic field. Radio scanners tuned to the correct frequencies can pick up the vibrations which occur too fast to be felt or heard.
To make their experimental glucose sensor, Grimes and his team modified these magnetoelastic tags with special chemical compositions.
The plastic threads are first coated with a material that reacts to changes in acidity. Added to that is a layer of glucose oxidase, a chemical that reacts with blood glucose.
When the sensor encounters glucose, the oxidase produces an acid which reacts with the undercoating and causes the sensor to swell. The tiny change in the sensor's shape varies the frequency of vibrations.
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