Fully inkjet-printed graphene/gold nonenzymatic biosensor for glucose detection

Diabetes mellitus worldwide patients are expected to total 366 million by 2030. Continuous monitoring of blood glucose levels is essential for diabetic treatment. Inkjet printing is one of the promising inexpensive techniques for fabricating printed electronics with high accuracy, minimum waste, and a variety of substrates to print on. Here we demonstrated an inkjet printable graphene (IJPG) ink made from mechanically exfoliated water-based salt-mediated graphene. A stable (> 3 months) IJPG ink with a high concentration of ∼ 7.5 mg/ml was formulated and printed on a polyimide sheet, followed by the printing of gold nanoparticles (Au NPs) ink to form IJPG/AuNPs electrodes used as a nonenzymatic biosensor for glucose monitoring. The number of printing passes of graphene and AuNPs was studied and optimized, reaching 0.272 mg graphene and 0.00143 mg Au-NPs total weight for each electrode expressing the edge of drop-on-demand inkjet-printing systems, which can make the utilization of noble metals feasible. The sensor manipulated a sensitivity of 140 µA.cm−2mM−1 and a linear range of 0.1–10 mM glucose concentrations with a limit of detection of 0.09 mM. Additionally, the sensor featured excellent selectivity against interfering metabolites, stability of peak current over 21 days, repeatability, and flexibility, enabling it to be presented as a practical non-enzymatic glucose sensor for point-of-care (POC) applications.