Suspended Graphene-Based Electrochemical Sensor for Ultra-Sensitive Detection of Electroactive Dopamine (neurotransmitter) Signals

Abstract

Graphene – a single atom thick 2D material, has demonstrated extraordinary potential as ultrasensitive and specific biological and chemical sensors1,2. This is because every carbon atom in suspended graphene is a surface atom which can be covalently/non-covalently interfaced with a wide range of chemical/biological species3 for detection at the single molecule level. Additionally, the charge transport through graphene can be modified via liquid gating, which forms a sensitive electrochemical method of detecting signals from charged species bonded to the graphene surface. Recently, graphene has demonstrated selective detection of electroactive signals from dopamine-a catecholamine neurotransmitters, which are found in the mammalian central nervous system4. Pristine graphene’s superior electronic and electrochemical properties can be exploited as analytical electrochemical sensors for measuring exocytosis during communication between cells under in vitro conditions, thereby monitoring cognitive and behavioural functions of living organisms We have developed a 3 mm X 3 mm graphene chip with an array of two terminal devices, connected in parallel, in which each individual device consists of a monolayer graphene suspended over multiple cavities and clamped by two metal contacts. Suspended graphene, as opposed to substrate-based graphene, significantly reduces the surface charge hindrances and allows for ultrasensitive detection of electroactive signals. The fabricated graphene chip has been successfully tested as a VOC and electrochemical sensor. Currently, testing is underway to use the device as an electrochemical dopamine sensor. We intend to discuss initial electrochemical dopamine sensing results as well as to explore possible collaborations with research groups for testing the graphene chip as an in-vitro neurotransmitter sensor.