Dopamine sensing with robust carbon nanotube implanted polymer micropillar array electrodes fabricated by coupling micromolding and infiltration coating processes

Abstract

Flexible electrochemical sensors are preferred to monitor the levels of neurotransmitters which are important to understand human central nervous system and diagnose/treat many brain-related diseases. Robust conductive coating is essential for these neural sensors to promote their sensitivity and selectivity. By coupling micropattern molding and infiltration coating processes, we successfully fabricated composite electrodes with part of carbon nanotubes (CNT) exposed to the sample while the rest of it embedded in polymer micropillars and the sensor base. Together with the micropillar array pattern, the partial implantation configuration provides the electrodes a stable coating with minimal conductivity loss in a 7-day impedance test. Cyclic voltammetric studies indicate a quasi-reversible behavior of dopamine and a retention of 93% signal after a two-hour fouling experiment. When detecting dopamine via differential pulse voltammetry (DPV), it exhibits a detection limit of 0.77 nM, quantification limit of 2.34 nM, and sensitivity of 0.453 nA/nM. Well separated DPV peaks were observed when sensing dopamine without and with excess uric acid, ascorbic acid, and glucose, common interfering bioactive compounds. Given successful demonstration on both rigid and soft substrate surfaces, this new fabrication method and its sensor products could help advance important in vivo neurotransmitter sensing and other electrochemical applications.