Painless diabetes test

A daily regimen of pricked fingers and blood tests is an essential part of life for someone living with diabetes.

But perhaps not for much longer, thanks to efforts by Dr Mak Paranjape and Dr John Currie, researchers at Georgetown Advanced Electronics Laboratory (GAEL) at Georgetown University, Washington DC who are aiming to make such painful procedures a thing of the past.

For the past few years, the Georgetown team has been developing and testing a new biosensor device for blood glucose monitoring. The size of a small bandaid plaster, it is designed to be worn anywhere on the body, where it samples tiny amounts of fluids that lie just beneath the skin.

The device is small and convenient, and makes measuring glucose levels pain-free and non-invasive.

Traditional blood monitoring techniques use a needle to make a relatively large, deep hole to extract blood droplets from the capillaries, which lie deeper under the surface of the skin.

Instead of puncturing a 'big' hole into the skin, the new biosensor works by making a tiny pore in the skin, through which interstitial fluid can rise.

It does this by painlessly removing a patient's outer-dermis, or dead-skin layer, by using a 'micro-hotplate' (or micro-heater), which measures about 50 microns square.

For 30 milliseconds, the hotplate is turned on to a temperature of 130^oC. It might sound hot, but in such a small spot, and for such a short time, a person cannot even detect the heat, or feel any pain, as it is applied to the outer layers of skin.

This hotplate causes a tiny micro-pore to form through which a little bubble of fluid passively emerges. The biosensor then reads the glucose levels in the sample fluid through tiny electrodes coated with a substance that reacts specifically to the glucose.

The biosensor project initially began through funding from the military, with the intention of developing a miniature device to remotely monitor the health status of soldiers in a battlefield.

The researchers'  tiny prototype chip, which acts as a patch on the skin and is called the B-FIT (Bio-Flips Integrable Transdermal MicroSystem), can obtain samples of fluid from under the skin one time every hour for a 24-hour period.

To support the design and development of the device, Dr Currie and Dr Paranjape received a Department of Defense contract for $3m over three years from DARPA, the US Defense Advanced Research Projects Agency.