Programmable Graphene e-Nose Sensor Arrays for Fast, Sensitive and Label-Free Identification of Chemical Vapors

Conventional electrical chemical vapor sensors are mostly based on charge transfer mechanisms and have struggled with the trade-off between sensitivity and response time. To address this challenge, our groups previously demonstrated a new type of fast, sensitive, and broad-spectrum electronic vapor sensor by exploiting the fringing field capacitance effect in graphene transistors. The typically trivial fringing field capacitance change due to analyte absorption is greatly amplified by both the graphene transistor and a micro-flow channel covering the surface of graphene. In this work, we demonstrate programmable graphene e-nose sensor arrays toward true label-free sensing and identification of chemical vapors. Individual graphene sensors within the 1D sensor array (up to 1 x 9) are optimized to offer sensitive (down to picogram) and fast (sub-second) detection toward a variety of analytes. More importantly, its responsivity toward different analytes can be programmed by electrostatic gating on the graphene transistor. By combining with advanced data analysis tools, the graphene e-nose array has the potential to offer label-free chemical vapor sensing without the need to individually functionalize each sensor as in traditional e-nose devices. We will also discuss the integration of the graphene e-nose sensor array with a micro-gas chromatography chip and a smartphone-sized custom PCB board for electronic control and readout and Bluetooth data communication. The graphene e-nose sensor arrays offer a sensing platform for real-time rapid on-site monitoring of complex gas mixtures including polar, nonpolar, organic, and inorganic molecules. Furthermore, the result should pave the way for fast, sensitive, and true label-free chemical vapor sensing and identification using nanoelectronic sensors.