Printable FET sensors with using GNH/MnO2 as channel material for non-enzymatic detection of bilirubin

Abstract

The accurate detection of bilirubin biomarker is vital for diagnosis of liver diseases. In this study, a novel field-effect-transistor sensor (FET) using aminated reduced graphene oxide flakes (GNH) decorated with manganese dioxide (MnO₂) as channel material has been introduced. The channel material (GNH/MnO₂) was first prepared via in-situ chemical reduction of Mn ions on the aminated reduced graphene oxide flakes, then formulated in ink solution, and finally printed on the channel of the device using extrusion printing method. The results showed the growth of needle-like MnO₂ nanostructure (firmly anchored on graphite flakes) which can act as an excellent catalyst for the oxidation reaction of bilirubin in the later sensing tests. Upon the addition of the targeted molecule (bilirubin), the charge neutrality point was significantly shifted when GNH/MnO₂ was used as the channel material (+25 mV) whereas this point was just slightly shifted (+0.1 mV) when MnO₂ was not introduced. The use of extrusion printing technique has also provided us with a conventional approach to produce low-cost devices with good reproducibility. The as-prepared FET sensors were able to detect bilirubin with a limit of detection (LOD) as low as 10⁻¹¹ M with good repeatability (relative standard deviation, RSD = 2.64 %). This research has demonstrated the potential application of printable sensing devices integrated with functional nanomaterials as advanced diagnostic tools.