Portable, battery-less and wireless radio frequency sensing of salivary glucose based on nonenzymatic hydrogel

Purpose Current screening methods for diabetes mellitus rely on invasive blood collection, which causes significant discomfort and anxiety, particularly in pediatric and geriatric populations. This study aims to present a battery-less, wireless radio frequency (RF) resonator for noninvasive detection of salivary glucose. Design/methodology/approach The resonator consists of two spiral copper inductance coils encapsulated in polyimide for insulation treatment and a glucose-sensitive hydrogel based on phenylboronic acid serves as the dielectric layer between the two inductance coils. The glucose-sensitive hydrogel undergoes volumetric changes upon glucose stimulation, which are transduced into resonant frequency shifts of the RF resonator. This sensor enable wireless readout through near-field coupling. Besides, the detection of saliva samples and correlation analysis between blood glucose levels and salivary glucose levels further demonstrate the system’s capacity for detection of salivary glucose. Findings This method provides a noninvasive, cost-effective solution for diabetes prescreening and monitoring. Results align closely with the glucose oxidase-peroxidase assay and demonstrate the ability to predict blood glucose trends. Originality/value This work introduces a novel hydrogel-based RF sensor for salivary glucose detection, eliminating the need for enzymes, batteries or microelectronic components. Its simplicity and scalability highlight potential applications in point-of-care diagnostics.