Researchers publish inertial microfluidics papers in top biomedical engineering journals
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A team of researchers from the University of Illinois Chicago’s Richard and Loan Hill Department of Biomedical Engineering has published two significant studies in leading biomedical engineering journals, advancing the understanding of inertial microfluidics, a field which explores how cells and particles behave in fluid flows.
The research team includes Richard and Loan Hill Professor Ian Papautsky, Associate Professor Zhangli Peng, postdoctoral associate Moein Naderi, and former graduate student Giuseppe Lauricella. In one study, published in Lab on a Chip, the team investigated how the tail of a sperm cell influences its movement through microfluidic channels. Their findings shed light on the physical forces that guide sperm migration, offering new insights into reproductive biology and fluid dynamics. In a second paper, published in Microsystems & Nanoengineering, the researchers reviewed computational methods used to model inertial microfluidic systems. This comprehensive overview highlights the growing role of simulation and modeling in designing next-generation biomedical devices.
Paper explains mechanisms, behavior of sperm cells with tail
Naderi, the first author on the Lab on a Chip paper, developed a numerical model to explore the inertial focusing behavior of sperm cells. The goal was to understand how these cells align and migrate within fluid flows.
“We now have a better understanding of what role the tail plays, and this is the first time that these impacts have been explored numerically in such detail,” Naderi said. “The tail impedes the rotation of the cells, which changes the way these asymmetric cells interact with the flow field. Therefore, we see them focusing in unexpected positions, near the channel outer wall.”
In this model, Naderi and his team incorporatedthe effects of the sperm tail and its oval shape on the inertial migration.
“We tried to explain the mechanisms behind the observed inertial focusing,” Naderi said.
“Our results revealed that the tail rather than the shape is the determining factor for the inertial migration behavior. We explain why this leads to very different behavior in sperm cells compared to other cell types, such as red blood cells.”
Papautsky’s lab led experimental investigations, while Peng’s lab developed numerical models. Former PhD candidate in Papautsky’s lab, Hua Gao, conducted some of the microfluidic experiments featured in the paper.
Previous studies often simplified sperm cells as spherical particles, overlooking the tail influence. This new model challenges that assumption and lays the groundwork for future research. The team has submitted a proposal to the National Science Foundation to continue developing technologies that explore how asymmetric and deformable cells interact with microfluidic flows.
Papautsky noted this research originated from work with the National Science Foundation Center for Advanced Design & Manufacturing of Integrated Microfluidics (CADMIM), where he serves as co-director with Abraham Lee of the University of California at Irvine.
“The focus of this paper was on bovine sperm because of the industrial partner collaboration,” Papautsky said. “There are other groups that are exploring using microfluidic devices for human in vitro fertilization applications, and this type of research could inform technologies for isolation or manipulation of human sperm in microfluidic devices.”
He added that the modeling approach developed by Naderi could be applied to other cells that have flagella, such as algae or bacteria, offering broader implications for biomedical device design. The other aspect of this paper is a clever modeling mechanism that Naderi developed, which combines essentially two different methods, and the same approach could be used to model other microorganisms or small particles.
Review paper explores computational advances in inertial microfluidics
Building on their experimental work, Lauricella, Papautsky, Naderi, and Peng wrote a review paper of computational methods in inertial microfluidics. Lauricella is the first author on this review paper.
“Microfluidic devices are increasingly used in biomedical applications, especially when cells are involved and exhibit very complex behaviors,” Papautsky said. “Unlike rigid particles, cells are often deformable, and the fluid itself can exhibit viscoelastic properties, making the dynamics far more intricate.”
To address these complexities, the team explored advanced computational techniques that go beyond traditional modeling approaches. Their review highlights methods such as Smoothed Particle Hydrodynamics (SPH), the Finite Element Method (FEM), and the Lattice Boltzmann Method (LBM), a computational fluid dynamics technique that is used to simulate fluid behavior.