Tiny biosensor measures glucose without needle pricks

Engineered by a team at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS, the biosensor combines measurement and digital analysis, and can transmit data wirelessly to a mobile device. Located on the patient's body, it measures glucose levels continuously using tissue fluids such as sweat and tears instead of blood. Measurement involves an electrochemical reaction that is activated with the aid of an enzyme. Glucose oxidase converts glucose into hydrogen peroxide (H2O2) and other chemicals whose concentration can be measured with a potentiostat. This measurement is used for calculating the glucose level. The chip, measuring 0.5 x 2.0mm, includes the nanopotentiostat as well as the diagnostic system. "It even has an integrated analogue digital converter that converts the electrochemical signals into digital data," explained Tom Zimmermann, IMS business unit manager. "In the past, you used to need a circuit board the size of a half sheet of paper. And you also had to have a driver. But even these things are no longer necessary with our new sensor." According to the researchers, earlier systems required about 500µA at 5V. The new device needs less than 100µA. This would allow a patient to wear the sensor for weeks, or potentially even months.