Graphene-based glucose sensors with an attomolar limit of detection

Diabetes mellitus , a prevalent metabolic disorder affecting hundreds of millions worldwide, demands continuous glucose monitoring for effective management. Current blood glucose monitoring methods, such as commercial glucometers, though accurate, are invasive and uncomfortable, highlighting the need for non-invasive, ultra-sensitive alternatives. Here, we present a glucose sensing platform based on electrolyte-gated graphene field-effect transistors (EG-GFETs) functionalized with glucose oxidase enzymes for ultra-sensitive detection. Detailed material characterization by Raman and X-ray photoelectron spectroscopies confirms successful enzyme immobilization, with a marked increase in nitrogen content from 0.9% to 7.6% atomic concentration on the graphene surface, indicating substantial glucose oxidase coverage. Raman analysis reveals significant p-type doping and tensile strain on the graphene channel directly correlating with glucose concentration from 1 nanomolar to 1 millimolar. The EG-GFETs demonstrate an ultra-low limit-of-detection of 1 attomolar, with a consistent Dirac point voltage shift of +26 ± 4 mV and a linear response across six orders of magnitude (up to 1 picomolar, with a sensitivity of 10.6 mV/decade). The sensor maintains high selectivity in complex media, such as artificial tears (with a limit-of-detection of 100 attomolar), underscoring its potential for non-invasive continuous glucose monitoring applications, also in wearable format.