A new, non-invasive skin patch made from thin-film graphene could measure glucose levels without the need for a finger-prick blood test. The device works by drawing out glucose from the fluid between cells across hair follicles, which are individually accessed via a miniaturized pixel array platform using a small electric current, in a process called electroosmotic extraction. Readings can be taken every 10 to 15 minutes over several hours and the data wirelessly transmitted to a mobile device, such as a smartphone or watch.
Diabetes is a serious worldwide health problem that is set to become even worse. The World Health Organization estimates that the number of people suffering from diabetes will increase to 366 million in 2030. This number was 171 million in 2000.
Diabetics regularly need to monitor their blood glucose levels, and they usually do this with a finger-prick test, which is uncomfortable to say the least. Researchers have recently developed a variety of non-invasive alternatives based on detecting glucose in sweat, tears or saliva but these techniques have their limits. For one, the levels of glucose detected can vary significantly, and secondly, many still require calibration with a conventional finger-stick.
Until now, the only technology to provide non-invasive, continuous glucose monitoring was the Gluco Watch Biographer, which received Food and Drug Administration approval in 2001. This watch works using reverse iontophoresis to extract interstitial fluid through the skin via electroosmosis. In this technique, a small electric field is applied across the skin, causing ions to flow. Since the skin has a net negative charge under normal physiological conditions, interstitial fluid flows from within the skin towards a cathode on the skin surface, where glucose is then detected and analysed.
