Leaky-Wave Antenna for Non-Invasive Continuous Glucose Monitoring

Abstract

Non-invasive continuous glucose monitoring requires sensing techniques capable of delivering stable, accurate, and real-time quantification of glucose-induced dielectric variations. This paper presents a microwave-based methodology that employs a leaky-wave antenna (LWA) to launch localized traveling electromagnetic waves and estimate glucose concentration through phase measurements at a fixed operating frequency. The LWA architecture enhances electromagnetic coupling with the material under test through controlled energy leakage, enabling strong linearity and high phase sensitivity within the physiological permittivity range (relative permittivity 68-70). In vitro measurements using fetal bovine serum-glucose samples demonstrate a total phase shift of 8.51 degree across glucose concentrations from 50 to 255 mg per liter. Preliminary in vivo experiments conducted on two human subjects show strong correlations between measured S11 phase and reference glucose levels (r=0.939 and r=0.906), confirming the potential of the LWA-based sensing mechanism to track dynamic glycemic variations in a proof-of-concept setting. These results highlight the potential of the proposed approach for practical, continuous, and non-invasive glucose monitoring.