Abstract

Microscale Flow Patterning

Moran Bercovici, Assistant Professor, Technion – Israel Institute of Technology

The ability to manipulate fluids at the microscale is a key element of any lab-on-a-chip platform, enabling core functionalities such as liquid mixing, splitting and transport of molecules and particles. Lab-on-a-chip devices are commonly divided in two main families: continuous phase devices, and discrete phase (droplets) devices. While a large number of mechanisms are available for precise control of droplets on a large scale, microscale control of continuous phases remains a substantial challenge. In a traditional continuous-flow microfluidic device, fluids are pumped actively (e.g. by pressure gradients, electro-osmotic flow) or passively (e.g. capillary driven) through a fixed microfluidic network, making the device geometry and functionality intimately dependent on one another (e.g. DLD, inertial mixer, H-separator, etc.). The advent of on-chip microfluidic valves brought more flexibility in routing fluids through microfluidic networks, adding a dynamic dimension to the static geometrical network. However, the number of degrees of freedom of valve-based systems is restricted by their dependence on bulky pneumatic lines (regulators, pressure systems, controllers), which are difficult to scale down in size and cost. In this talk I will present our ongoing work leveraging non-uniform EOF and thermocapillary flows to control flow patterns in microfluidic chambers.  By setting the spatial distribution of surface potential or a spatial temperature distribution, we demonstrate the ability to dictate desired flow patterns without the use of physical walls. We believe that such flow control concepts will help break the existing link between geometry and functionality, bringing new capabilities to on-chip analytical methods.