Sensing nitric oxide neuronal messengers using screen-printed carbon micro-electrode arrays

This paper presents the development of a microfabricated electrochemical sensor for measuring neurotransmitter activity in brain tissue. Electrochemical sensing is used to detect neuronal messengers such as nitric oxide (NO). Sensing is accomplished using the principle of an oxidation-reduction (redox) reaction at the carbon electrode surface that produces a current signal proportional to the NO concentration. The carbon microsensors are patterned onto an array using a carbon polymer ink that is screen-printed onto electrically conductive traces. Thick SU-8 photoresist serves a dual-role, acting both as an insulating layer and also as a mold for the carbon ink. Surface profiling showed that our process produces mesa-shaped electrode structures. The electrochemical activity of the sensors is tested potentiostatically and NO sensitivity is demonstrated. Sensitivity to various interferents is also tested to determine electrode selectivity. Microfabricated sensor arrays would provide a novel experimental means to study the spatial and temporal neurochemical activity across brain tissue.