Rail induced lateral migration of particles across intact co-flowing liquids

Abstract

This paper presents a rail guided method to apply a Layer-by-Layer (LbL) coating on particles in a microfluidic device. The passive microfluidic approach allows handling suspensions of particles to be coated in the system. The trajectory of the particles is controlled using engraved rails, inducing lateral movement of particles while keeping the axially oriented liquid flow (and the interface of different liquids) undisturbed. The depth and angle of the rails together with the liquid velocity were studied to determine a workable geometry of the device. A discontinuous LbL coating procedure was converted into one continuous process, demonstrating that the chip can perform seven consecutive steps normally conducted in batch operation, further easily extendable to larger cycle numbers. Coating of the particles with two bilayers was confirmed by fluorescence microscopy.

Rail configuration for lateral particle transport across intact co-flows: effect of wall and rail geometry on liquid and particle transport

“…Although this chip shows the best color conservation, it has a technical limitation (the requirement for an envisioned LbL coating is that the rail depth is below 150 μm, because only then the liquid above the rail is of the same nature as the liquid in the rail 18 ).…”

“…9). Three types of behavior were observed: (i) particles follow the rail, (ii) particles escape the rail (see also 18 ) or (iii) particles get stuck in the rail. We consider that the particles “follow the rail” when 100% of the same size particles remain in the rail, since we want to ensure equal coating of all the particles in the chip.…”

“…Previously, 18 we introduced the concept of the rail, defined the conditions for the liquid flow rate and depth of the rail required to keep the same liquid in the rail as above the rail, what is the necessary condition for the coating reaction to occur. We also presented the proof of concept of LbL particle coating.…”

Layer-by-Layer Nanoparticle Assembly for Biomedicine: Mechanisms, Technologies, and Advancement via Acoustofluidics

“…The schematic illustration of this process can be seen in Figure 12C. 152 3.6.3. Inertial Microfluidics.…”

“…C) Images from optical microscopy of the channel at different distances along the flow profile where a) no particles flowing and b) two particles seen following the guided rail path, through different coating materials. Reproduced from ref ( 152 ). Available under a CC-BY 4.0 license.…”