Automatic processing of solutions for chemical analyses using an electrowetting-based valve and an integrated cell

A concept and a device for automatic handling of solutions using an electrochemical cell integrated in a microflow channel are proposed. An electrowetting-based valve was formed in a flow channel of poly(dimethylsiloxane) (PDMS) to separate two solutions in a mixing area. Another flow channel with a cell was formed to transport an electrolyte solution and activate the cell. Since the cell was electrically connected to the valve, the valve opened when the electrolyte solution reached the cell and activated it. To demonstrate the applicability to chemical analyses, a solution containing glucose, and another solution containing glucose oxidase (GOD), horseradish peroxidase (HRP), and amplex red were mixed by the automatic operation, and the enzymatic reactions were allowed to proceed. Fluorometric detection of a product (resorufin) showed clear relation between the fluorescence intensity and the concentration of glucose.