Abstract
The rapid detection of postprandial hyperglycaemia (PPHG) is imperative for the diagnosis of diabetes and the assessment of health risks for nondiabetics. Battery-free flexible glucose sensors are a promising tool for glucose sensing with a relatively low burden on biological tissues and living bodies because they are more lightweight and flexible than conventional battery-driven glucose sensors. However, existing battery-free glucose sensors are unsuitable for the practical detection of hyperglycaemia because of their long response time (>1 h) and response fluctuation. In this research, we demonstrated a unique combination of materials and device design-phenylboronic acid (PBA) hydrogel integrated with an inkjet-printed interdigitated capacitor (IDC)-that enabled rapid response to the change in the glucose concentration. In particular, the following three essential capabilities have been demonstrated: (1) quick response time (<5 min) to mouse serum under hyperglycaemia in a battery-free setting, (2) conformability of soft PBA hydrogel suitable for use on biological surfaces, and (3) controlled design of the signal transducer enabled by digital fabrication. We believe that these capabilities serve as core technologies toward the development of tissue-interfaced battery-free glucose sensors with improved response time.