New Implantable Optical Glucose Sensor

If the ‘cure for diabetes‘ doesn’t pass successfully through clinical trials, at least diabetics wouldn’t have to prick themselves to check their blood sugar. That is, if professor Gerald Loeb and his team of researchers at the University of Southern California perfect their implantable optical glucose sensor.

Researchers led by Gerald Loeb, a biomedical-engineering professor at the University of Southern California, are now working on a glucose-sensor design based on optical technology. The design shows promise for making sensitive, affordable, and less invasive sensors.
The technique involves measuring the change in fluorescent emissions that occurs when glucose binds to certain molecules. The sensor is a tiny optical fiber that could be implanted in a patient’s skin. To read glucose concentrations, a portable analyzer will shine ultraviolet light into the free end of the fiber and measure the fluorescence, says Loeb.
Attached to the end of the fiber inside the skin is a polyethylene-glycol polymer matrix interspersed with pairs of tightly bound chemicals, each tagged with a different fluorescent molecule. Under ultraviolet light, the bound molecules shine at one wavelength. When the researchers place the matrix in a glucose solution, glucose molecules knock out and replace one of the chemicals, dextran. As a result, the chemical complex starts emitting at two different wavelengths. The ratio of the fluorescence intensities at the two wavelengths is in proportion to the glucose concentration.
According to Loeb, the sensor should be cheap and disposable. “Essentially, it’s a dot of polymerized goop on the end of an optical fiber,” he says. “A few-centimeters-long optical fiber is going to be pennies, and the dot of goop would be even less.”
It might also be more reliable than existing devices, because the chemistry doesn’t consume glucose. Commercially available implantable sensors measure the voltage caused by a chemical reaction that consumes glucose. If the concentration around the sensor goes down, and glucose from the surrounding tissue doesn’t flow in quickly enough, one could be measuring a value that is lower than the actual concentration in the body, Loeb says.

Full article at MIT’s Technology Review . . .