Low-cost micro valves based on electrolysis inside hydrogels

For a Lab-on-Chip platform for Point-of-Care use, integrated controlling of liquid flow at an affordable price is essential. Besides micro pumps, also valves may be required e.g. to form closed reaction chambers or to direct the flow of a liquid. Microfluidic valves based on electrochemical gas generation inside a hydrogel have therefore been fabricated. The valves are suitable for mass fabrication and are able to gas-tightly seal off a microfluidic channel. As the valve can be considered as tightly closed now, the resistance of the valve towards the applied pressure has to be evaluated. The pump pressure was therefore stepwise increased. After each step, the tightness of the valve was tested by closing the on/off valve. In all cases, the pressure kept stable at the level of the pressure applied by the pump before. The valves can withstand a pressure of more than 50mbar. Above this value, the valves still can be used to dramatically increase the flow resistance and thus the pressure drop of a channel, which is sufficient for flow direction in microfluidic systems