A flexible electrochemical glucose sensor with composite nanostructured surface of the working electrode

• A flexible electrochemical sensor was fabricated into the ISF extraction chip to build a wearable micro device for continuous glucose monitoring.
• Composite nanostructured surface with graphene and AuNPs was constructed on the WE to enable accurate measurement of low levels of glucose.
• Graphene was directly written onto the tiny-sized WE surface by inkjet printing method without complicated CVD deposition and transferring process.
• AuNPs and GOD were electrodeposited onto the WE surface without any protection for the other parts that did not need the modification.

Detecting hypoglycemia remains a great challenge with regard to continuous glucose monitoring in clinical settings. This paper investigates a novel, flexible three-electrode electrochemical sensor with a composite nanostructured working electrode surface that has been modified by graphene and gold nanoparticles in order to detect low levels of glucose with high accuracy. The sensor electrodes were fabricated on a polyimide substrate using the flexible printed circuit board (PCB) method. Graphene was modified directly onto the working electrode surface via inkjet printing, an emerging method for micro-scale fabrications, to enable glucose detection at low levels. Gold nanoparticles were electrodeposited directly onto the graphene layer to enhance the sensitivity of the sensor. The experimental results demonstrate that the proposed sensor can precisely measure glucose with a linear range of 0–40 mg/dL and a detection limit of 0.3 mg/dL (S/N = 3), thereby demonstrating potential for hypoglycemia detection. Moreover, this flexible sensor was suitable for integration within a microfluidic chip, which could be used to transdermally extract and collect ISF, such that a wearable device could be developed for continuous glucose monitoring.