Investigation of particle movement in irregularly shaped channels in inertial fluidics for scale up applications in bioprocessing

Abstract

Particle separation is a vital step in many analytical chemistry, biomedical diagnosis, and environmental applications. Inertial microfluidics has emerged in recent years as a promising tool for a wide range of flow cytometric tasks including cell separation, cell counting and mechanical phenotyping. In inertial fluidics, a transverse inertia-induced lift force across streamlines is inherently accompanied with higher order of magnitude convection mass transfer (channel Reynolds number >10), in contrast to microdevices working mainly based on diffusion mass transport phenomenon (Stokes flow) or low-Re flows, increasing throughput significantly. Emerging inertial focusing technique as an alternative method to microfiltration has brought remarkable benefits such as a continuous and clog-free system with lower maintenance costs. These features along with its relative ease of scalability to reach a relevant industrial scale will facilitate its potential adoption in various industries such as waste water treatment and bioprocessing. Of particular interest, dealing with a broader range of particle sizes up to one order of magnitude larger than cell sizes (a > 50 µm) in bioprocessing requires scaled-up channels to avoid clogging. However, Dean-coupled inertial focusing has not been studied in detail when the channel hydraulic diameter is greater than DH ≈ 0.3 mm. Moreover, with the advancement of cell therapy industry in recent years, cell purification at downstream processing introduces some new challenges. While removing particulates from manufactured cell products, using routine membrane technologies similar to protein manufacturing industry do not work as well. This work focuses on the design and development of a membrane-less filtration and separation device using inertial focusing for a large range of particle sizes. To this end, inertial focusing is investigated in straight and mainly curved channels due to their scalability, throughput and efficiency. Inertial focusing is profoundly reliant on the cross-sectional shape of channel and it affects not only the shear field but also the wall-effect lift force near the wall region. The wall-effect lift force is known as a determining factor for cross-lateral migration that leads to a reduced number of equilibrium positions. In order to investigate this, a rectilinear channel with trapezoidal cross-section is designed to break down the symmetrical condition in conventional rectangular microchannels for a broad range of channel Re number (20 50). Finally, a trapezoidal straight channel along with a bifurcation was designed and used for continuous filtration of a…