An electrochromism-equipped enzymatic biofuel cell system combined with hollow microneedle array for self-powered...

A disposable, self-powered enzymatic biofuel cell (BFC) sensor integrated with a hollow microneedle array (HMNA) for glucose monitoring in interstitial fluid (ISF) is reported. The HMNA enables painless and minimally invasive ISF extraction. The BFC uses dehydrogenase (GDH) in conjunction with NAD⁺, diaphorase (DI), and vitamin K₃ (VK₃) serving as electron transfer mediators as the anode catalyst and Prussian blue (PB) as the electrochromic cathode. Glucose oxidation at the anode generates electrons that cause PB to change the color at the cathode, allowing for visual glucose concentration determination. The open-circuit potential (OCP) of the sensor is 0.14 V, with a maximum power density of 0.07 µW·cm^-2, at a glucose concentration of 14 mM. The sensor shows good performance in glucose sensing with a linear relationship between the R/B ratio and glucose concentrations ranging from 0 to 14 mM. This disposable device offers a promising approach for non-invasive and self-powered glucose sensing.