Microstrip line-based microfluidic sensors for glucose monitoring using microwave approach: a review

Abstract

Glucose monitoring is critical for diabetes management, yet traditional invasive methods remain fraught with discomfort and logistical challenges. Recent advancements in microwave-based microstrip line sensors offer a transformative alternative, leveraging electromagnetic interactions with biological tissues to detect glucose-induced dielectric changes non-invasively. This review examines the evolution of microstrip line-based sensors, emphasizing their design principles, operational mechanisms, and clinical applicability. Current challenges, such as environmental interference, tissue heterogeneity, and signal stability, hinder widespread adoption. Among the diverse technologies evaluated, resonator-based sensors, particularly split-ring (SRR) and swastika-shaped geometries that demonstrate superior performance due to their multi-parameter sensing capabilities, high sensitivity (e.g., 148.367 Ω/(mg/mL)), and compact design. These sensors integrate reflection coefficient phase, magnitude, and impedance measurements, enhancing robustness against noise and biological variability. While metamaterial and implantable antennas show promise, their limitations in scalability or biocompatibility underscore the practicality of resonator-based systems. Future efforts must prioritize clinical validation and integration with machine learning to address individual variability. In conclusion, resonator-based microstrip sensors represent the most viable path toward reliable, continuous glucose monitoring, combining innovation with practicality to redefine diabetes care.