Fabrication of Screen-Printed Carbon Electrode Arrays for Sensing Neuronal Messengers

Deciphering the methods of communication between neurons and ensembles of neurons in the brain is a major area of interest in the field of neuroscience. An array of sensors designed to sense specific neuronal messengers or neurotransmitters should provide a better method to study their spatial and temporal activity across a tissue. Screen-printing is a simple and inexpensive technique for fabricating arrays of sensors that can be used to monitor neurotransmitter activity in the brain. One important neuronal messenger known to actively modulate neuronal excitability is nitric oxide (NO). Carbon has been shown to interact with NO in an oxidation-reduction reaction that produces a current proportional to the amount of NO present. The proposed design uses carbon polymer inks screen printed onto aluminum traces to form the sensors. A thick, photodefineable epoxy resin, known as SU-8, serves as an insulator and a mold for the carbon ink. A potentiostat is used to apply a 900 mV voltage between the carbon sensor and a reference electrode positioned in the bath of the experimental setup. The current produced indicates the concentration of NO in close proximity to the carbon site. The screen-printing technique provides an elegant way to produce an array of individual carbon sensors. The carbon sensor array promises a novel approach to mapping the distribution of neurotransmitters in brain tissue.