Development of a non-invasive transcutaneous blood glucose monitoring method using an ISFET biosensor

A transcutaneous blood glucose monitoring method has been developed by combining an SOS/ISFET (silicone-on-sapphire/ion sensitive field effect transistor) biosensor with an SEF (suction effusion fluid) collecting technique. The SEF collecting cell has a stainless steel mesh at its bottom which is kept in a weak vacuum condition so as to suck up transcutaneous SEF and deposit it in a reservoir above. An ISFET biosensor, consisting of immobilized enzyme membranes, enables the detection of glucose concentrations in very small samples. The method has been successfully applied to non-invasive monitoring of human blood glucose levels during tests involving 75 g OGTT (oral glucose tolerance test). Glucose concentrations measured with SEF showed good correlation with those obtained directly from serum. Results suggest the feasibility of a portable blood monitoring system.