Fabrication and Experimental Study of Lab on a Chip with Electrochemical Sensor and Electrowetting on Dielectric by Screen Printing

This research introduces the development and experimental validation of a plastic lab-on-a-chip platform that seamlessly integrates electrowetting-on-dielectric (EWOD) technology with an embedded electrochemical sensor. The system is composed of two primary sections: an H-junction EWOD mechanism designed to combine buffer solutions with sample droplets, and a screen-printed graphene-carbon paste electrode (SPGE) serving as the electrochemical detection unit positioned at the junction’s terminus. Unlike conventional T-junction setups, the customized H-junction enables the concurrent fusion of four individual droplets, significantly improving analytical flexibility. Fabrication of the EWOD network employed screen-printed silver paste technology. The sensing assembly features a working electrode, a counter electrode fabricated from SPGE, and a reference electrode formed by screen-printed silver/silver chloride. Analytical performance was tested by monitoring enzymatic reactions via cyclic voltammetry, with hydrogen peroxide (H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) selected as the target analyte. The findings demonstrate that the SPGE-integrated EWOD chip performs reliably in detecting enzymatic activities related to H<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>.