Time-resolved mapping of neurotransmitter fluctuations by arrays of nanocavity redox-cycling sensors

We introduce a novel device for the spatiotemporal detection of neurotransmitters on-chip. Our device features an array of individually addressable nanocavity sensors that utilize redox-cycling for the localized electrochemical determination of neurotransmitter concentrations. This effect is based on rapid, repeated redox-reactions between two closely spaced electrodes and results in a high amplification of the electrochemical signal of individual molecules. Each sensor is equipped with two independently biased electrodes that are separated by an ∼65 nm wide cavity, thus enabling efficient redox-cycling amplification. The sensors feature entry ports in the micrometer regime and can be closely packed for the chemical mapping at high spatial resolutions. In this paper, we present the devices capabilities in neurotransmitter detection. The sensors are electrochemically characterized and their functionality is demonstrated by measuring localized dopamine fluctuations in a microfluidic channel.