Integrated Microfluidic System Based on Electrowetting and its Application to Amino Acid Sensing Based on Electrochemiluminescence

Abstract

A microfluidic system to transport and mix solutions was fabricated and used for the detection of amino acids. A solution filled in the injection port was transported through a space between an elongated gold working electrode and a protruding structure of polydimethylsiloxane (PDMS). The transport was possible because the electrode surface was made hydrophilic by changing the potential of the gold working electrode. The same principle was used to mix two solutions. To demonstrate the system's applicability, optical biosensing based on electrochemiluminescence (ECL) was conducted on the chip. A necessary reagent solution (Ru(bpy)₃²⁺) and a sample solution (amino acid) were transported and mixed. ECL was observed on a platinum working electrode by applying a positive potential. Linear relationships were observed between the ECL intensity and the amino acid concentration.