Ethanol fermentation bioreactor for microfluidic actuation

We present a concept for autonomous, long-term and high-pressure fluid transport on microfluidic chips, which is fully bio-compatible and, in principle, also compostable. The actuation principle is based on ethanol fermentation, a well-known biological process in which microorganisms such as yeast cells convert sugar molecules into cellular energy and thereby produce ethanol and carbon dioxide (CO2) as metabolic waste products. A two-chamber fluidic system separated by a flexible membrane is proposed for active fluid transport utilizing a bio-reactor. One chamber, connected to the outside via a pressure-sensitive valve, contains the fluid to be actuated, the other one the culture medium for the yeast cells. Once the yeast cells are injected into the culture medium, ethanol fermentation and thus the production of CO2 starts, which builds up pressure on the membrane and hence also on the fluid chamber. As soon as the switching point of the pressure sensitive valve is reached, fluid transport at a predefined and constant flow rate starts.