Biosensor monitors glucose from fluids other than blood

Technology that continuously monitors glucose levels from fluids other than blood could bring finger-pricking regimes to an end for diabetics.

Developed by researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS, the new body-worn biosensor overcomes the limitations of previous devices that were said to be too big, imprecise and consumed too much power.

According to a statement, the principle of measurement involves an electrochemical reaction that is activated with an enzyme. Glucose oxidase converts glucose into hydrogen peroxide and other chemicals whose concentration can be measured with a potentiostat. This measurement is used for calculating the glucose level.

A feature of the biosensor is a chip measuring 0.5 x 2.0mm, which contains the entire diagnostic system.

‘It even has an integrated analogue-digital converter that converts the electrochemical signals into digital data,’ said Tom Zimmermann, business unit manager at IMS.

The biosensor transmits data via a wireless interface, so a patient can monitor his or her glucose level via a mobile device.

‘In the past, you used to need a circuit board the size of a half-sheet of paper,’ said Zimmermann. ‘And you also had to have a driver. But even these things are no longer necessary with our new sensor.’

In addition, the sensor is said to consume substantially less power. Earlier systems required about 500µA at five volts; now, it is less than 100µA. That increases the durability of the system — allowing the patient to wear the sensor for many weeks.

The use of a passive system makes this durability possible; the sensor is able to send and receive data packages, but it can also be supplied with power through radio frequency.

According to Fraunhofer, a future development could see the biochip control an implanted miniature pump that, based on the glucose value measured, indicates the precise amount of insulin to administer.