Rapid Selective Detection of Ascorbic Acid Using Graphene-Based Microfluidic Platform

In this paper, we present a compact microfluidic platform for selective detection of ascorbic acid. The microfluidic chip was fabricated by xurography technique with microfluidic channel placed between the silver electrodes. To increase the conductivity of the platform and enhance electron transfer process, a graphene sheet was deposited in the gap between the electrodes. The suspension of tablets with ascorbic acid and a mixture of ascorbic acid and isomalt, a sugar substitute, were injected in the microfluidic channel. Measuring electrical parameters at the silver contacts, it was possible to successfully differentiate ascorbic acid from isomalt. The sensing mechanism of the developed microfluidic platform is based on the increase of the overall conductivity with the increase of the concentration of ascorbic acid, resulting in the decrease of the resistive parameters and increase of the capacitive parameters of the proposed equivalent electrical circuit. The addition of graphene was found to improve the response linearity by 5.28% and lower the limit of detection and quantification by 12%, compared to the reference structure without graphene.