High‐Performance Flexible and Printed Graphene‐Field Effect Biosensor for Ferritin Detection

Abstract A flexible and printed field‐effect biosensor with a graphene channel (Gr‐FET biosensor) is designed and characterized to detect ferritin. The biosensor offers an onboard Ag/AgCl gate to give stable transfer characteristics with a significantly low gate leakage current of 0.06% of the minimum drain current. Further, the proposed Gr‐FET shows 1.5–3 times higher transconductance (g_m) with a value of g_m,hole up to 400 µS and g_m,electron up to 250 µS, compared to the reported printed electrolyte‐gated Gr‐FET on flexible substrates. The Gr‐FET operation is also optimized to have a minimal hysteresis effect for reliable sensing operation. The Gr‐FET shows fairly linear characteristics at a low ferritin concentration (0.05–0.5 µg L⁻¹) with sensitivity as high as ≈230 mV/(µg L⁻¹) and a very low limit of detection (LOD) ≈27 ng L⁻¹. Given the cost‐effective fabrication process and scalability, the proposed printed Gr‐FET biosensor can be deployed on a large scale for early diagnosis of iron deficiency anemia.