Droplet based microfluidic device integrated with ink jet printed three electrode system for electrochemical detection of ascorbic acid

Abstract

Droplet based microfluidics expands its applications in various fields including biological, pharmaceutical, chemical and cosmetic industries. However, the detection of droplets and its content is one of the major challenging tasks necessitating an urgent attention. Electrochemical detection holds a promising technique for analyzing the droplet velocity, size and content. However, fabrication of an effective, low-cost and reliable droplet based electrochemical device for detection of biological analytes have not been explored to the full extent. In this work, a droplet based microfluidic electrochemical device has been fabricated using inexpensive fabrication technique with numerous benefits such as high throughput, low sample volumes, minimum cross contamination, lower energy demands and shorter analysis times. A microfluidic T junction was fabricated and integrated with a three electrode system fabricated using inkjet printing method. Droplets were generated in the integrated device at varying flow rates, 1 μL/min, 2.5 μL/min and 5 μL/min, with ascorbic acid as dispersed phase and hexadecane oil as continuous phase. Cyclic voltammetry was performed in the integrated device to detect ascorbic acid. Parameters like scan rates (25 mV/s, 50 mV/s and 75 mV/s), flow rates and different concentrations (2 mM, 3 mM and 4 mM) on the electrochemical detection of ascorbic acid in the integrated device were investigated. It was observed that at lower flow rate conditions i.e., 1 μL/min and a combination of 2 mM concentration at 50 mV/s, proper oxidation peaks were obtained with a sharp peak at a potential of 0.28 V. As a whole, in the integrated device, cyclic voltammetry technique was successfully implemented for the first time in a droplet based electrochemical device.