Nanostructured Photonic Hydrogels for Continuous Glucose Monitoring

Diabetes has become one of the top 10 causes worldwide, with ~6.7 million deaths recorded in 2021. The development of low-cost, simple, and reusable sensors can provide a potential platform for reducing diabetic complications, which can be fatal. Phenylboronic acid (PBA) based hydrogel sensors with imprinted Aztec nanostructures were demonstrated for rapid, real-time, and continuous glucose monitoring. A simple and rapid fabrication was carried out to imprint nanostructures. Aztecs are comprised of hexagonally packed ring shape pyramids with nano steps. Two sensor geometries were demonstrated: stand-alone (SA) and optical fiber (OF). The optical response of sensors was observed for the glucose concentration range of 0 – 50 mM in both transmission and reflection modes. Upon exposure to the glucose concentrations, the hydrogel matrix undergoes swelling. The swelling occurs due to cis-diol (present in glucose) binding with phenylboronic acid. A sensitivity of 3 and 1.5 µW/mM was documented for SA and OF sensors along with a fast response time of 20 s. The sensor response was also measured in the physiological glucose range for healthy and diabetic people. A smartphone readout was employed for practical use. The optical response of the sensor in different glucose concentrations was measured using a smartphone photodiode. The developed sensors may find their application for real-time, remote, and continuous glucose monitoring systems.