Optimization of a Ferrocene Carboxylic Acid-Based Enzymatic Glucose Sensor for Continuous Glucose Monitoring

Continuous glucose monitoring (CGM) systems are indispensable for managing diabetes, providing real-time glucose trends for effective therapeutic decision-making. The present work focuses on designing and developing an enzymatic electrochemical sensor with a three-electrode configuration for CGM applications. We designed, fabricated, and tested the metal electrodes on silicon/silicon oxide (Si/SiO2) as well as polyethylene terephthalate (PET) substrates. The sensor performance is optimized with respect to variables, such as area of electrodes, type of electrodes, and enzyme-mediator ratio for continuous glucose detection. A flow setup is also developed for in vitro testing by a controlled supply of glucose. The fabricated sensor exhibits a detection range of 50–400 mg/dL and a sensitivity of 34 nA/mgdL $^{-{1}}$ /mm2 at an operating potential of 0.35 V with minimal susceptibility to common interference molecules. The continuous glucose measurements in vitro show a retention of 88% of the sensor’s initial response after seven days of operation. The simplified microfabrication process combined with the use of stable, readily available mediator molecule and a simple immobilization technique, eliminating the need for elaborate synthesis procedures, offers a scalable and cost-effective approach to develop an indigenous CGM system.