Graphene Nanosensor for the Detection of Small Organic Compounds Using an Insect Olfactory Receptor

Insect olfactory receptors have evolved to detect a wide range of chemicals and biomolecules, offering a promising foundation for next‐generation chemical sensors. We report the first direct integration of the odorant receptor MhOR5 from Machilis hrabei onto a graphene field‐effect transistor (gFET) for selective, label‐free detection of small organic compounds (SOCs). Large scale production of MhOR5 was achieved for the first time, yielding a stable tetrameric protein (80% purity) with up to 3‐month stability. High‐quality gFETs were fabricated at the wafer scale and quality controlled before utilization, demonstrating highly reproducible chips. The MhOR5‐functionalized gFETs were tested against sixteen chemically diverse SOCs, including eugenol, DEET, hexanol, and octanol, across a concentration range of 200 n m to 10 m m . Each analyte induced a concentration‐dependent response in the sensor. Binding analysis within the tested SOCs revealed the strongest affinity for acetophenone (logK D = 0.28), and the weakest for sulcatone (logK D = 4.4). Notably, the sensor distinguished eugenol from its structural isomer, isoeugenol, an achievement difficult to detect using conventional sensors. This work establishes a modular biosensing platform that couples the molecular selectivity of insect olfactory receptors with the exceptional sensitivity of graphene‐based sensors. The MhOR5‐gFET biosensor demonstrates significant potential for applications in biotechnology, diagnostics, and biosurveillance.