A Low-Temperature Thermopneumatic Actuation Principle for Gas Bubble Microvalves

We introduce a novel type of microfluidic actuator in which a trapped air bubble functions as the thermally controlled volume displacing element. The pressure of the trapped air pocket is controlled by the changing equilibrium gas composition for static operation and by thermal expansion for dynamic operation. The volume displacement is determined by the liquid surface tension and the valve geometry. A fully functional demonstrator device was successfully fabricated and tested. The absence of moving mechanical parts, the electrical control of the valve, and the limited required actuation temperature make the actuator suitable for control of large-scale integration fluidic networking in biotechnical applications.