Mid-infrared photoacoustic sensing of glucose in keratinocyte solutions

This study is aimed to develop a non-invasive laser-based photoacoustic (PA) glucose sensor, which can track variations of glucose concentration in vitro and in vivo at a level of physiological interest (i.e. 30-500 mg/dl). Unlike many other optical attempts which use NIR light, we employ light from the mid-infrared spectral region, where glucose shows strong characteristic absorption and has less interference with other tissue components. Using mid-infrared light limits the penetration into human skin to less than 100 μm as a consequence glucose has to be sensed within the interstitial fluid of the epidermis since blood capillaries are not reached.