Biosensor Measures Glucose Levels without Needle
A biosensor of the size of a few nanometers can measure glucose levels of patients suffering from diabetes. Daily finger pricking is a routine part of their lives, but the new biosensor can measure glucose levels with the fluid from tears could soon free them from the pain of pin pricks.
At present, patients with type 1 diabetes must place a tiny drop of blood on a test strip; this is the only way they can ascertain the blood glucose value, in order to inject the correct amount of insulin needed. As well as being an unpleasant and often painful hassle that must be carried out several times a day, pricking may also cause inflammation or cornification of the skin.
The new non-invasive measurement approach, engineered by a team of German researchers from Fraunhofer-Gesellschaft in Munich, contains a tiny chip that combines measurement and digital analysis. Information gathered from the chip is in turn radioed to a mobile device that allows patients to keep a steady eye on their glucose levels.
Could the German team's new diagnostic system consign pricking to the history books, and result in widespread use of remote measurement devices? The innovative biosensor, which must be located on the patient's body, can measure glucose levels continuously using tissue fluids other than blood, such as in sweat or tears.
Measurement of the Glucose Level
The principle of 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.
Tom Zimmermann, from Fraunhofer-Gesellschaft, comments: '[The chip] even has an integrated analogue digital converter that converts the electrochemical signals into digital data.
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.'
This sensor also consumes significantly less power than earlier attempts at developing such systems. Whereas before, 500 microamperes at 5 volts was required, now less than 100 microamperes are required, meaning the system is much more durable, allowing the patient to wear the sensor for weeks, or even months.