Microfluidic In-Flow Decantation Technique Using Stepped Pillar Arrays and Hydraulic Resistance Tuners

Abstract

Separating the particles from the liquid component of sample solutions is important for several microfluidic-based sample preparations and/or sample handling techniques, such as plasma separation from whole blood, sheath-free flow focusing, particle enrichment etc. This paper presents a microfluidic in-flow decantation technique that provides the separation of particles from particle-free fluid while in-flow. The design involves the expansion of sample fluid channel in lateral and depth directions, thereby producing a particle-free layer towards the walls of the channel, followed by gradual extraction of this particle-free fluid through a series of tiny openings located towards one-end of the depth-direction. The latter part of this design is quite crucial in the functionality of this decantation technique and is based on the principle called wee-extraction. The design, theory, and simulations were presented to explain the principle-of-operation. To demonstrate the proof-of-principle, the experimental characterization was performed on beads, platelets, and blood samples at various hematocrits (2.5%–45%). The experiments revealed clog-free separation of particle-free fluid for at least an hour of operation of the device and demonstrated purities close to 100% and yields as high as 14%. The avenues to improve the yield are discussed along with several potential applications.

Editorial for the Special Issue on Particles Separation in Microfluidic Devices

“…In this Special Issue, 11 research papers, and two review articles are published. Five papers [1-5] and a review article [6] present (1) passive microfluidic techniques using inertial focusing [1,6], deterministic lateral displacement (DLD) [2,3], and hydrodynamic methods [4,5]. The remaining papers [7][8][9][10][11][12] and a review article [13] cover (2) active microfluidic techniques using electric [7][8][9], acoustic [10], magnetic [11,12], and optical forces [13].() Passive microfluidic technique: Bogseth et al proposed a co-flow inertial microfluidic device that is tunable in multiple ways for adaptation to different application requirements [1].…”

Microfluidic platform for multiple parameters readouts in a point-of-care

“…Blood plasma separation from undiluted blood without the help of external forces is essential to create a POC device. Most of these passive techniques suffered from clogging problems and low yield [84,85]. This issue limits the amount of plasma available for analysis and consequently the type of test that can be implemented using microchip filtration.…”