Courses » Workshop 3

Prof. Thomas Gervais, Polytechnique Montréal
Étienne Boulais, Polytechnique Montréal
Pierre-Alexandre Goyette, Polytechnique Montréal
Prof. Mohammad Ameen Qasaimeh, New York University Abu Dhabi
Prof. Jean Berthier, University of Washington

Workshop Description:
In many emerging applications in chemistry and the life sciences, the traditional "closed-channel network" view of microfluidics fails to make a difference. This is the case whenever microfluidic systems must interface with the standards of the pharmaceutical industry: the pipette, the petri dish and the well plate. The whole subfield of open (or open-space) microfluidics has been developed to better serve applications in reagent delivery, surface processing and probing.

The laws of open space microfluidics depart from the simple quasi-1D flow in a serpentine channel. They can involve free surface flows, quasi 2D flow fields, and significantly more complex transport patterns which are nevertheless elegant and translatable into simple design rules for new microfluidic applications. On the fabrication level, open microfluidic systems are well suited for 3D printing, which can provide truly 3D channel networks, simple interfacing, and fast implementation with open-source model sharing.

In this workshop, which is a sequel to the excellent previous workshop at earlier microTAS conferences given by the IBM Research Zurich team, we hope to provide the attendee all the knowledge and a few tricks required to quickly design, fabricate and operate their own open microfluidic systems. A special focus will be given this year on modeling open-space flows and transport, 3D printing, and reconfigurable microfluidics system which offer whole new possibilities to process surfaces with reagents at low costs.

Overview of Material to Be Covered and What Attendees Can Expect to Take Away From the Workshop:
This workshop part contains 3 lectures:
  1. The first lecture will introduce the concept of the microfluidic probe, where the fluidics delivery is physically decoupled from the bottom sample. The microfluidic probe combines concepts of scanning probes and hydrodynamic flow confinement that is achieved with fluids push-pull configuration. Attendees will learn about the working concepts of the different flow regimes within the various probes' designs, including the microfluidic dipoles, quadruples, and heptapoles. Then, different biological and clinical applications of the probe will be discussed, including protein patterning, micro-immunohistochemistry, and cell chemotaxis. Further, attendees will be briefed with the potential of integrating the probe with other technologies for achieving sequential cell separation and patterning, multiplexed isolation of circulating tumor cells, and performing single cell biopsies.
  2. The second lecture will provide a framework and fabrication strategy to generalize open space systems with large number of flow apertures (Goyette et al, Nat. Commun., 2019). Attendees will learn the basic laws governing reagent transport in open-space systems and elegant mathematical tricks to characterize them. Using videos and examples, they will be walked through the CAD drawing, 3D printing, operation, and applications of microfluidic multipole devices. Applications will be showcased in immunoassays, roll-to-roll printing, and general surface processing.
  3. The third lecture gives an introduction to "Open-Channel Microfluidics". First, the spontaneous flow condition in arbitrary-shape open channels is presented using the concept of generalized Cassie angle. It is shown how this condition must be modified in open channels of non-uniform cross-sections. The case of slightly pressurized open capillary flows is also examined. Then, the dynamics of capillary flows in open channels is presented. It is shown that an "average friction length" replaces the (hydraulic) radius that appears in the Lucas-Washburn law. The determination of this friction length is investigated for arbitrary cross-sections. A special attention is given to case of open networks for which the Lucas-Washburn law does not apply. Third, an investigation of open-channel two-phase flows is examined. The different modes of motion of droplets and plugs are analyzed. Finally, some applications of open-channel capillary flows are presented and a list of useful references is suggested.
Who Should Attend:
The workshop is intended for a broad audience with interest in interfacing microfluidics with open surfaces for applications in the life sciences. It is particularly suited for engineers, chemists and physicists interested in transport phenomena, fluid dynamics, CAD, and fabrication and who seek to expand their knowledge to design their own open microfluidics applications.

Participants Will Need the Following:
No special requirements for attending. Matlab, Catia, COMSOL, are the softwares required to run the open-access codes afterwards.