by Kefeng Zeng

Diabetics are finger-prickers by necessity, but a reprieve may be in store for their sore digits. A bean-size sensor, slipped under the skin and read wirelessly, could take the pain and hassle out of blood-sugar monitoring. The system “listens to the vibrations of the sensor inside you” to measure glucose levels, says the inventor, Craig Grimes, an electrical engineer at Penn State University.

Grimes’s implant consists of a magnetic sensor (similar to those used in anti-shoplifting tags) that vibrates in response to specific radio frequencies. To turn the sensor into a sugar monitor, Grimes coated it with two unique polymers: One layer converts glucose into an acid, the other detects changes in pH. When acidity increases, the pH-sensitive polymer shrinks, causing the sensor’s mass to decrease and its resonance, or vibrational frequency, to increase.

A monitoring device worn on the wrist houses a magnetic coil that detects resonance changes. “You just wave whatever body part past [the monitor],” Grimes says, and a millisecond later, you have your glucose reading. The system is testing well in animals, and Grimes says clinical trials could begin within a year.