Enhanced inertial focusing of microparticles and cells by integrating trapezoidal microchambers in spiral microfluidic channels

Abstract

In this work, manipulating width and equilibrium position of fluorescent microparticles in spiral microchannel fractionation devices by embedding microchambers along the last turn of a spiral is reported.

High-Efficiency Small Sample Microparticle Fractionation on a Femtosecond Laser-Machined Microfluidic Disc

“…There was no difference after changing the direction of rotation in these experiments, which means that Coriolis force had little to no effect on particle focusing, and since 5 and 10 µm particles have a c /D h ≥ 0.07, then lift forces are dominant and are responsible for particle focusing in the channel [52,57]. The trapezoidal microchambers contribute in shifting the focusing position towards them by gradual entry and exit, as optimized in a previous study [31]. The results were monitored after the experiment on an inverted microscope (Leica DM IL LED) equipped with a blue LED light source (Leica SFL 100, both Leica Microsystems GmbH, Wetzlar, Germany).…”

“…In principle, more than 20 channels could be realized in the case of a single disc-center-concentric source chamber. A design implemented in an earlier work [31] about integrating microchambers along spiral microfluidic channels was considered and returned promising results that will be discussed in a following section. The main focusing channels has a width of 120 µm and a depth of 50 µm (the drawing of the focusing channel is provided in the Supplementary Material Drawing S1).…”

“…In a previous work [31], microchambers were implemented to shift the particles from the center of a spiral channel to the inner wall by changing the velocity profile between consecutive microchambers. Different shapes of microchambers were tested and evaluated with fluorescent 2 µm particles to explore suitable designs in terms of focusing the line's width and distance from the inner wall.…”

“…New forces are introduced in rotational flow systems, such as Coriolis and centrifugal forces that can change the velocity profile inside the channel; hence changing particles equilibrium positions. Integrating trapezoidal microchambers along the channel's side wall is proven to benefit the focusing efficiency in terms of the focusing position and focusing line's width [31]. In this work, we study microfluidic discs with straight channels and integrated trapezoidal microchambers as a method for low sample isolation of 5 and 10 µm particles, resulting in a focusing efficiency of~92% for 5 µm particles and~98% for 10 µm particles.…”

Sheath-less high throughput inertial separation of small microparticles in spiral microchannels with trapezoidal cross-section

“…Several attempts have been made to focus and separate 2 mm in spiral channels, however, most designs used a sheath uid and worked at low ow rates due to the high pressure induced in the small channel geometry as reported by Bhagat et al and Lee et al 31,32 In a previous work, 33 2 mm particles were focused by implementing microchambers along the last turn of a spiral channel; that design produced thin focusing streams but could not separate microparticles since all sizes focused near the inner wall. In this paper, we study the trapezoidal microuidic channel's ability to separate small microparticles down to 2 mm in high throughput without utilizing a high-pressure pump and without adding a sheath uid that complicates the testing setup and might limit its use in low setup areas, achieving a separation between 2 and 5 mm, and 2 and 10 mm uorescent microparticles.…”