A Smartphone-Interfaced, Flexible Electrochemical Biosensor Based on Graphene Ink for Selective Detection of Dopamine
Ritvik Muralidharan, Vinay Chandrashekhar, Derrick Butler, Aida Ebrahimi
Abstract
This study reports the fabrication of flexible electrochemicaldopamine sensors using a facile, low temperature (300°C) process based on spin-coating of commercially available graphene ink onto a polyimide (PI) substrate. The electrochemical testing and surface characterization were achieved using cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The graphene-ink based biosensor demonstrated a limit of detection (LoD) of 100 nM of dopamine in PBS and a dynamic concentration range up to 1 mM, with excellent specificity against uric acid and ascorbic acid. The sensor is also resilient against mechanical deformation (<; 12% change in peak currents during maximum bending). Furthermore, we demonstrated that a subsequent solution-phase treatment of graphene ink in copper sulfate (CuSO4) followed by annealing in air at 200°C improves the sensor LoD from 1 μm to 5 nM in artificial sweat. Wireless data transfer via Wi-Fi in tandem with an on-chip sensor integrated with an in-house built potentiostat is also developed to demonstrate the applicability of the platform for point-of-care applications.