Flexible, disposable, and portable self-powered glucose biosensors visible to the naked eye

Diabetic patients need to measure their blood glucose level ∼5 times a day using glucose sensor. However, typical glucose sensors require additional power supply and equipment to interpret glucose concentration. In this study, flexible, disposable, and portable self-powered glucose biosensor is suggested to quickly measure glucose concentration with the naked eye. The theory of enzymatic biofuel cell is adopted for its self-powered operation. This glucose biosensor includes glucose dehydrogenase (GDH) and Prussian blue (PB) as biocatalysts for anode and cathode, while glucose oxidation reaction and reduction reaction of PB are utilized as the main reactions. In electrochemical evaluations, maximum current density and onset potential of anodic and cathodic reactions are 0.39 and – 0.53 mA/cm², and 0 and 0.3 V vs. Ag/AgCl. Furthermore, when many interfering compounds are included, anodic catalyst is only sensitive to glucose, while this shows linearity even at a low glucose range of 0.5 – 10 mM (R² = 0.999). When 3, 5, and 10 mM glucose solutions corresponding to low, normal, and high glucose level are prepared and injected into glucose biosensor, each glucose is well recognized by the naked eye through the number of PB bars whose color is automatically changed after one min.