Sensitive detection of glucose enantiomers using open-ring resonator-based metamaterial sensor

Abstract

Glucose, as the core substance of energy metabolism in living organisms, exhibits significant differences in bioavailability, metabolic pathways, and physiological functions between its d- and l-enantiomers. Specifically, d-glucose serves as a key substrate in the cellular tricarboxylic acid cycle, while the l-enantiomer cannot be metabolized due to the absence of glucokinase, making it a non-caloric, diabetic friendly sweetener. The stark contrast in their bioactivity and application scenarios highlights the critical importance of developing rapid, label-free, and highly sensitive enantiomer discrimination technology for precision medical diagnostics and functional food development. This study innovatively proposes and validates a terahertz metamaterial sensor based on an open-ring resonator for precise identification of glucose enantiomers. Operating under a TE (transverse-electric) mode, the sensor demonstrates dual-resonance responses at 0.409 and 0.652 THz. Through full-wave simulation optimization using CST Microwave Studio®, the device was fabricated via UV photolithography and characterized with a terahertz frequency-domain spectroscopy system. Simulation results predict a high refractive index sensitivity of up to 222.3 GHz/RIU, while experimental measurements demonstrate the sensor’s capability for specific discrimination between d-glucose and l-glucose at concentrations as low as 2 mmol/l. At 8 mmol/l glucose concentration, the transmission peak intensity increase for l-glucose was 1.96 times greater than that of d-glucose. This sensor provides an innovative tool for real-time blood glucose monitoring and personalized diabetes treatment, demonstrating the unique technical advantages of terahertz metamaterials in the field of biological chiral recognition.