Microfluidic systems for chemical kinetics that rely on chaotic mixing in droplets

Abstract

This paper reviews work on a microfluidic system that relies on chaotic advection to rapidly mix multiple reagents isolated in droplets (plugs). Using a combination of turns and straight sections, winding microfluidic channels create unsteady fluid flows that rapidly mix the multiple reagents contained within plugs. The scaling of mixing for a range of channel widths, flow velocities and diffusion coefficients has been investigated. Due to rapid mixing, low sample consumption and transport of reagents with no dispersion, the system is particularly appropriate for chemical kinetics and biochemical assays. The mixing occurs by chaotic advection and is rapid (sub-millisecond), allowing for an accurate description of fast reaction kinetics. In addition, mixing has been characterized and explicitly incorporated into the kinetic model.

Ideal micromixing performance in packed microchannels

“…The mixing of multiple reagents was isolated in the liquid slugs by introducing the immiscible carrier phase in the winding microchannels, and the chaotic advection appeared in slugs by internal circulations, which could stretch and fold the fluids striation, eventually the intensification of the mixing in droplets could be obtained (Bringer et al, 2004). Reactions in slugs in microchannels have attracted many researchers due to the elimination of Taylor dispersion and the enhanced mixing performance by internal circulation, such as measurement of fast reaction kinetics parameters (Song and Ismagilov, 2003), protein crystallization (Zheng et al, 2004), synthesis of nanoparticles (Khan and Jensen, 2007), etc.…”

A microfluidic chip for controlled release of drugs from microcapsules

“…It should be noted that the DWlCs randomly move around in the droplet due to the local turbulence flow or advection of the liquid inside the droplet during the process of the droplet formation and being captured by a chamber at the beginning. 19 After a certain period of time, the DWlCs are eventually become stationary inside the droplet when the turbulence flow or advection of the solution inside the droplet becomes negligible, which has been observed as shown from Figs. 5(b) to 5(d).…”

Microfluidics-based systems biology

“…For a more detailed explanation, a thorough review on the theory behind performing droplet-based kinetic measurements is available in ref. 61.…”