Orateur
Description
Microfluidic devices have revolutionized flow control at small scales. Programming localized flow patterns remains challenging. Here, we introduce a new approach to generate programmable and localized flow in microfluidic chips: We use a deformable chip, whose flexible ceiling of the microfluidic channel deforms downward. We leverage this system to break the temporal and spatial symmetries of the periodic flow in the microfluidic channel and produce a net fluid flow.
We investigate the influence of a cylindrical obstacle in this configuration. The vertical ceiling displacement generates a circumferential flow localized around the obstacle. Flow velocity and direction can be tuned by adjusting the phase delay of the actuators, or actuation frequency or amplitude. The flow can be described using an unsteady Hele-Shaw cell model.
This phenomenon represents a form of Stokes drift in which the obstacle converts sequential ceiling deformations into rotational flow. Finally, we show that this principle may be extended to more complex flow patterns by varying further the shape or number of the obstacles, or by combining this flow with an externally-controlled Poiseuille flow.