Beating Poisson stochastic particle encapsulation in flow-focusing microfluidic devices using viscoelastic liquids

Abstract

The encapsulation and co-encapsulation of particles in microfluidic flows is essential in applications related to single-cell analysis and material synthesis. However, the whole encapsulation process is stochastic in nature, and...

Viscoelastic particle encapsulation using a hyaluronic acid solution in a T-junction microfluidic device

“…A micromilling machine (Minitech CNC Mini-Mill) was used to fabricate the microfluidic device on a rigid polymethylmethacrylate (PMMA) substrate with a thickness of 1.2 mm, using the same approach employed in previous works. 16 Firstly, a 2-mm-wide tip was used to mill the substrate down to 300 µm to obtain a uniform surface. A 100 µm metal tip was used to mill the channel onto the PMAA substrate.…”

“…Span 80 (Sigma Aldrich, UK), a non-ionic surfactant, was added at a concentration of 1 wt % to the oil to stabilize the interface between HA and oil, in agreement with previous works. 15,16 The viscosity of the mineral oil taken from the same batch employed here was previously measured to be 29 mPa•s. 15,16 The interfacial tension values between 0.1 wt % HA in PBS and mineral oil was here measured using a force tensiometer (Sigma 702, Biolin Scientific) equipped with a du Nouy ring.…”

“…15,16 The viscosity of the mineral oil taken from the same batch employed here was previously measured to be 29 mPa•s. 15,16 The interfacial tension values between 0.1 wt % HA in PBS and mineral oil was here measured using a force tensiometer (Sigma 702, Biolin Scientific) equipped with a du Nouy ring. In this methodology, the du Nouy ring was first submerged in the HA solution (heavier phase), while mineral oil (lighter phase) was poured on top.…”

“…In this manuscript, we studied the encapsulation of particles in viscoelastic liquids in a T-junction microfluidic device, with the ultimate aim of identifying experimental conditions for which the encapsulation efficiency was larger than the Poisson limit. In analogy with previously published works on the topic, 15,16 we first studied the viscoelastic droplet formation phenomenon at various imposed flow rate ratios Q d /Q c , where Q d is the flow rate of the dispersed phase (i.e., either PBS or HA) and Q c is the flow rate of the continuous mineral oil phase (Figure 2). Under the qualitative point of view (Figure 2a), for the same set of imposed volumetric flow rate values, the droplet size did not differ significantly between Newtonian and non-Newtonian droplets, in agreement with previous finding on viscoelastic droplet microfluidics.…”

“…Very recently, the same principle originally introduced by Edd et al 9 was employed within the framework of particle encapsulation using non-Newtonian viscoelastic liquids. 15,16 In these works, the authors took advantage of the recently discovered viscoelastic particle ordering phenomenon 17,18 to demonstrate a viscoelastic particle encapsulation up to 2-folds larger than the Poisson limit. In one case, 15 the authors employed a commercial T-junction glass microfluidic devise together with an aqueous shear-thinning xanthan gum suspending liquid.…”