Elastocapillary flow driven lab-on-a-membrane device based on differential wetting and sedimentation effect for blood plasma separation

Abstract

We report an elastocapillary flow—driven lab on a membrane device based on differential wetting and sedimentation effect for the separation of plasma from whole blood. Interaction between a thin polydimethylsiloxane (PDMS) membrane (thickness ~35 μm) bonded to the edge of a PDMS substrate and a sample blood drop (of volume ~70 μl) gives rise to deformation of the soft membrane due to the capillary forces providing a conduit and consequent elastocapillary flow of blood. The surface of the PDMS membrane is hydrophilic up to a certain length along the flow direction to support the elastocapillary flow and hydrophobic thereafter to impede the flow. In the hydrophobic region, owing to a much smaller sedimentation time scale (~100 s) as compared to the capillary flow time scale (~1000 s), sedimentation of blood cells occurs thus facilitating separation of plasma from the blood cells in the hydrophobic region. The role of differential wetting and sedimentation effects on the blood plasma separation is studied. The effects of membrane width and thickness, length of the hydrophilic region, erythrocyte sedimentation rate (ESR) on the separation of plasma were investigated. Using a membrane of width 3 mm, thickness 35 μm, total length 25 mm and hydrophilic length of 4 mm and 70 μl of whole blood with ESR varying in the range 4 mm h−1 to 40 mm h−1, the volume of plasma was in the range of 7.5 μl to 20 μl, respectively, which corresponds to a plasma recovery of 22%–49%, respectively. Purity of the plasma from the proposed device was compared with that obtained from centrifugation which showed a good match. The device was integrated with a commercially available detection strip to detect the level of glucose present in the plasma from blood samples of healthy and diabetic patients which are in qualitative agreement with that obtained from conventional tests.

Ultralow-Fouling Zwitterionic Polyurethane-Modified Membranes for Rapid Separation of Plasma from Whole Blood

“…Various microfluidic-based plasma separation devices have been developed for on-site testing and point-of-care diagnostics. These devices can be classified into different categories based on the separation mechanism, including asymmetric capillary, , blood cell sedimentation, − crossflow filtration, − inertial force, , erythrocyte capture, and size-selective − separation. However, microfluidic-based devices require either highly diluted blood or yield only a small amount of plasma, ranging from a few to tens of microliters.…”

Moving contact lines and dynamic contact angles: a ‘litmus test’ for mathematical models, accomplishments and new challenges

“…The role of the substrate beyond providing a geometric constraint and, implicitly, the surface tension featuring in the Young equation until recently received relatively little attention albeit from prominent researchers [145][146][147][148][149] who used a variety of approaches and mainly highlighted the issues arising when deformation of the solid substrate is to be taken into account. However, the reversal of dynamic properties of the liquids and solids in an increasing number of applications [150] and, especially, the increasing importance of modelling biological systems with their ubiquitous membranes and soft tissues [151] are now placing elasticity of the solid substrate in static and dynamic wetting on the research agenda, primarily experimental [152,153]; see also a recent review [73] for a list of references. In this area, experiments have almost invariably used only one setup, namely a liquid drop placed on a deformable substrate, so that fishing out information about wetting from the overall picture of the drop's statics and dynamics is not always possible.…”

Self‐Folding Using Capillary Forces

“…Conventional micro‐ and nano‐fluidic devices are fabricated by soft‐lithography, molding and bonding PDMS, resulting in inherently planar geometries and channels with rectangular cross‐sections. Nevertheless, channels with circular cross‐section more accurately mimic biological fluidic channels and enable uniform fluid flow . Capillary assembly can provide a means to roll up films and create microfluidic channels with circular cross‐sections.…”

“…Nevertheless, channels with circular crosssection more accurately mimic biological fluidic channels and enable uniform fluid flow. [145] Capillary assembly can provide a means to roll up films and create microfluidic channels with circular cross-sections. For example, Mirsaidov et al prepared graphene nanotubes using capillary force self-assembly of suspended graphene on grids using water (Figure 7a).…”