Screen printed electrochemical detector combine with digital microfluidic microchip

In this work, a screen-printed electrochemical detector with electrowetting on dielectric (EWOD) digital microfluidics lab on a chip was designed, fabricated, and experimental studied for biological, biomedical, and chemical analysis. For the design, the electrochemical EWOD digital microfluidics system consists of T-junction EWOD microchip for merging buffer reagent and analyte droplets and three screen-printed electrochemical detectors at the end of T-junction. The detectors consist of three electrodes: carbon working electrode, carbon counter electrode and silver/silver chloride reference electrode with minimal reagent consumption and rapid analysis. The systems has been successfully fabricated and tested for rapid analysis. In experiment, the electrochemical detector with EWOD microchip was fabricated and tested to control moving (merging and transporting) droplet on the microchip to analyte at three electrochemical detector. For analysis, the electrochemical detectors was demonstrated for minimal reagent consumption which were potassium ferricyanide and L-ascorbic. The concentration of the reagent were varied from 1, 2, 3, 5, 7 and 10 mM for analysis. Microdroplets of buffer reagent and analyte droplet solution was mixed and detected by cyclic voltammetry. The total analysis time including droplet mixing and measurement was less than 20 seconds.