An electronic Venturi-based pressure microregulator

Microfluidic systems often use pressure-driven flow to induce fluidic motion, but control of pumps and valves can necessitate numerous external connections or an extensive external control infrastructure. Here, we describe an electronically controlled pressure microregulator that can output pressures both greater and less than atmospheric pressure over a range of 2 kPa from a single pressurized air input of 110 kPa. Multiple independently controlled microregulators integrated in one device can potentially share the same air input. The microregulator operates by using embedded resistive heaters to vary the temperature of a gas flowing through a converging–diverging Venturi nozzle between 25 °C and 85 °C with a resolution of 33 Pa °C⁻¹. We established the switching speed of the microregulator by accurately moving 1 μL droplets of water in a microchannel via pneumatic propulsion. Droplet deceleration from approximately 1 cm s⁻¹ to zero velocity required less than 0.8 s. The component is readily integrable into most device designs containing fluidic channels and electronics without introducing additional fabrication complexity.