Sensors and Actuators B xxx (2003) xxx–xxx Integrated microfluidic system with electrochemically actuated on-chip pumps and valves

A microfluidic system was constructed by integrating on-chip micropumps and check valves that function by means of a hydrogen bubble that is generated or extinguished electrochemically. Essential elements consisted of thin-film three-electrode systems, including a platinum black working electrode. Micro flow channels and containers for electrolyte solutions were formed on a polydimethylsilixane (PDMS) substrate. The growth and shrinkage of the bubble were controlled reproducibly by setting the working electrode potential at a constant value. The elastic nature of the bubble clogged in a valve compartment in the middle of the flow channel hindered the effective passage of the solution. The bubble was also effective in separating two different solutions. By making the valves open and close cooperatively, a solution could be introduced into the system and transported in the flow channel. When two dye solutions were transported and merged in a flow channel, sheath flows were observed, reflecting a low Reynolds number. As a model system, two solutions containing luciferin and luciferase were introduced separately, transported, and mixed. Chemiluminescence originating from the enzymatic reaction was observed