Microfluidic Fabrication Solutions for Tailor-Designed Fiber Suspensions

Abstract

Fibers are widely used in different industrial processes, for example in paper manufacturing or lost circulation problems in the oil industry. Recently, interest towards the use of fibers at the microscale has grown, driven by research in bio-medical applications or drug delivery systems. Microfluidic systems are not only directly relevant for lab-on-chip applications, but have also proven to be good model systems to tackle fundamental questions about the flow of fiber suspensions. It has therefore become necessary to provide fiber-like particles with an excellent control of their properties. We present here two complementary in situ methods to fabricate controlled micro-fibers allowing for an embedded fabrication and flow-on-a-chip platform. The first one, based on a photo-lithography principle, can be used to make isolated fibers and dilute fiber suspensions at specific locations of interest inside a microchannel. The self-assembly property of super-paramagnetic colloids is the principle of the second fabrication method, which enables the fabrication of concentrated suspensions of more flexible fibers. We propose a flow gallery with several examples of fiber flow illustrating the two methods' capabilities and a range of recent laminar flow results.

Dynamics of Flexible Fibers in Viscous Flows and Fluids

“…1ce). The presence of oxygen close to the PDMS walls prevents polymerization in these regions keeping the fabricated object free to flow in the microchannel ( [8,55]). Finally, self-assembly of colloids is a reliable technique that produces very flexible, high aspect-ratio particles but their sedimentation due to their high density can be limiting ( Fig.…”

“…Finally, self-assembly of colloids is a reliable technique that produces very flexible, high aspect-ratio particles but their sedimentation due to their high density can be limiting ( Fig. 1h) ( [8,47,151]).…”

“…Beam-bending measurements can be implemented in a microfluidic channel to perform in situ measurements (see fig.1k) ( [32]). [8]. (i) Electrospun fibers, [93].…”

Transport of flexible fibers in confined microchannels

“…Compared to other situations studied previously ( [28,29,34]), where the flexible fiber is held fixed in the channel, the fiber studied here is free and the deformations induced by the fluid are rather small. In order to obtain significant deformation we work with highly flexible fibers, i.e.…”

Microfluidic In-Situ Measurement of Poisson’s Ratio of Hydrogels

“…Slabs of hydrogel with controlled geometry and position were directly fabricated inside the micro-channel using microscope-based photolithography [13]. This method has been extensively detailed in previous works [13][14][15][16][17][18][19], and just the essential steps are detailed here and schematically represented in Figure 1. The channel, filled with an oligomer solution and a photo-initiator, is exposed to a pulse of UV light of controlled duration.…”