Control of pressure-driven components in integrated microfluidic devices using an on-chip electrostatic microvalve

Pressure-driven actuators play a critical role in many microfluidic technologies, but the ancillary equipment needed to operate pneumatic and hydraulic platforms has limited their portability. To address this issue, we created an electrostatic microvalve used to regulate pressures in hydraulic control lines. In turn, these control lines are able to actuate pressure-driven components, e.g., microvalves. The electrostatic microvalve is fabricated exclusively with soft-lithographic techniques, allowing it to be directly integrated in a microfluidic chip. The electrostatic microvalve also contains a passive structural element that balances the pressure on the top and bottom sides of the actuating membrane. This feature enables the microvalve to induce pressure changes up to 20 kPa with electric potentials less than 320 V. When the microvalve is integrated into a microfluidic “pressure amplifier” circuit, the pressure output of the circuit can be tuned with the voltage applied to the microvalve. This integration allows for different types of pressure-driven components to be actuated with variable pressures, and thus eliminates the need for off-chip pressure regulation. In the example reported here, only one actuator is required to adjust the pressure of a single hydraulic line.