Enhancing the capture efficiency and homogeneity of single-layer flow-through trapping microfluidic devices using oblique hydrodynamic streams

Abstract

With the aim to parallelize and monitor biological or biochemical phenomena, trapping and immobilization of objects such as particles, droplets or cells in microfluidic devices has been an intense area of research and engineering so far. Either being passive or active, these microfluidic devices are usually composed of arrays of elementary traps with various levels of sophistication. For a given array, it is important to have an efficient and fast immobilization of the highest number of objects, while optimizing the spatial homogeneity of the trapping over the whole chip. For passive devices, this has been achieved with two-layers structures, making the fabrication process more complex.In this work, we designed small microfluidic traps by single-layer direct laser writing into a photoresist, and we show that even in this simplest case, the orientation of the main flow of particles with respect to the traps have a drastic effect on the trapping efficiency and homogeneity. To better understand this phenomenon, we have considered two different flow geometries: parallel and oblique with respect to the traps array, and compared quantitatively the immobilization of particles with various sizes and densities. Using image analysis, we show that diagonal flows gives a spatial distribution of the trap loading that is more homogeneous over the whole chip as compared to the straight ones, and by performing FEM and trapping simulation, we propose a qualitative explanation of this phenomenon.

Microtubules restrict F-actin polymerization to the immune synapse via GEF-H1 to maintain polarity in lymphocytes

“…Microfluidic chips were made using an original design from the team of Jacques Fattaccioli (ENS Paris, IPGG) ( Mesdjian et al, 2021 ). RTV PDMS was mixed at a ratio 1:9, poured in epoxy cast replicates of the microfluidic chips, and cooked until fully polymerized.…”

Microtubules restrict F-actin polymerization to the immune synapse via GEF-H1 to maintain polarity in lymphocytes

“…Microfluidic chips were made using an original design from the team of Jacques Fattaccioli (ENS Paris, IPGG) (47). RTV PDMS was mixed at a ratio 1:10, and poured in epoxy cast replicates of the microfluidic chips, and cooked until fully polymerized.…”

Phenotyping polarization dynamics of immune cells using a lipid droplet-cell pairing microfluidic platform

“… 29 We first developed a two-dimensional depth-averaged computational fluid dynamics - finite element model of the microfluidic chamber with exactly the same approach that the one proposed in. 71 The numerical simulations are performed with COMSOL Multiphysics (version 5.3). We consider a planar and incompressible flow, at steady state, and a Newtonian fluid with a dynamic viscosity of Pa.s.…”