A flexible microneedle sensor for long-term, enzyme-free glucose monitoring with high sensitivity and stability

Blood glucose monitoring is of paramount importance for patients with diabetes. However, conventional glucose meters exhibit limited accuracy and present challenges for prolonged use, primarily due to the high consumption of glucose oxidase (GOD) and their sensitivity to temperature and environmental factors. phenylboronic acid (PBA), benefiting from its reversible reaction with glucose and superior stability, holds potential as a promising medium for long-term glucose monitoring.

In this study, a microneedle substrate with low solubilization loss was obtained for the detection of glucose levels in interstitial fluids (ISF) by co-mixing silk fibroin and proline (Pro) as a PBA carrier. This microneedle sensor demonstrated a sensitive and linear response to glucose concentrations ranging from 1 to 20 mM in vitro, exhibiting correlation coefficients of 0.999 for the range of 1-12 mM and 0.997 for 12-20 mM. It displayed enhanced stability and a prolonged monitoring duration when compared to GOD-based commercial glucose meters. Additionally, it was unaffected by environmental factors such as temperature and pH, and demonstrated strong interference resistance. It successfully achieved real-time, long-term glucose concentration monitoring for up to 21 days (only ∼14 days for GOD-based measurement).

This study presents a novel approach to the development of wearable glucose monitoring devices characterized by extended duration and enhanced stability. We believe that this work makes an exciting and important contribution to the development of stable, highly sensitive and long-term glucose monitoring devices with the potential to significantly improve diabetes management.