Wearable Biosensors for Continuous Glucose Monitoring

Abstract

Continuous glucose monitoring (CGM) systems have transformed diabetes management by providing real-time interstitial glucose data, replacing intermittent self-monitoring finger-prick testing and enabling closed-loop insulin delivery. This study developed and characterised three wearable electrochemical biosensor architectures -- enzymatic amperometric (glucose oxidase, GOx), non-enzymatic molecularly imprinted polymer (MIP), and near-infrared (NIR) optical photoplethysmography -- for transcutaneous and interstitial glucose detection, evaluating sensitivity, selectivity, stability, and clinical accuracy against ISO 15197:2013 CGM standards. The GOx-based flexible microneedle array sensor, fabricated on polyimide substrate with Pt electrode arrays and Nafion/GOx/polyurethane functional layers, achieved sensitivity of 14.84 +- 0.84 µA/mM in the 2-20 mM glucose range with a detection limit of 0.18 mM. The MIP polymer sensor on screen-printed carbon electrodes demonstrated 92.4% selectivity against major interferents (ascorbic acid, uric acid, acetaminophen) and 4-week operational stability (< 8% response decay). NIR optical sensors achieved glucose prediction with RMSEP = 0.84 mM using a 10-component PLS regression model across 80 calibration samples. Clinical accuracy evaluation against YSI glucose analyser reference (n = 240 paired measurements in 30 type 1 diabetic volunteers over 7 days) showed 96.8% of GOx sensor readings within Zone A+B of the Clarke Error Grid and 97.2% within +-15% of reference for the MIP sensor above 4.2 mM. These findings establish the enzymatic GOx microneedle array as the most clinically accurate CGM platform and identify the MIP sensor as a viable calibration-free alternative with extended shelf stability.