Distributed neurochemical sensing: in vitro experiments

Experimental results characterizing a very-large scale integration (VLSI) potentiostat sensor system for recording distributed neurotransmitter activity are presented. Neurotransmitter concentration is electrochemically transduced using an array of carbon electrodes. The resultant currents are then processed in parallel by eight integrated potentiostat channels consisting of a current amplification stage, current-mode delta-sigma A/D converter, and counting decimator. Electrical characterization has shown that the VLSI potentiostat is sensitive to picoampere levels of input current. Furthermore, both static and dynamic neurochemical measurements of dopamine are verified in vitro, proving the utility of the device for brain slice studies. Lastly, a biologically inspired experiment, whereby the catabolism of dopamine is mimicked with the addition of the COMT enzyme to modulate dopamine levels in vitro.