title: Sub-micrometer-precision, three-dimensional (3D) hydrodynamic focusing via "microfluidic drifting".
abstract: In this article, we demonstrate single-layered, "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing devices with particle/cell focal positioning approaching submicron precision along both lateral and vertical directions. By systematically optimizing channel geometries and sample/sheath flow rates, a series of "microfluidic drifting" based 3D hydrodynamic focusing devices with different curvature angles are designed and fabricated. Their performances are then evaluated using confocal microscopy, fast camera imaging, and side-view imaging techniques. Using a device with a curvature angle of 180°, we have achieved a standard deviation of ±0.45 μm in particle focal position and a coefficient of variation (CV) of 2.37% in flow cytometric measurements. To the best of our knowledge, this is the best CV that has been achieved using a microfluidic flow cytometry device. Moreover, the device showed the capability to distinguish 8 peaks when subjected to a stringent 8-peak rainbow calibration test, signifying the ability to perform sensitive, accurate tests similar to commercial flow cytometers. We have further tested and validated our device by detection of HEK-293 cells. With its advantages in simple fabrication (i.e., single-layered device), precise 3D hydrodynamic focusing (i.e., submicrometer precision along both lateral and vertical directions), and high detection resolution (i.e., low CV), our method could serve as an important basis for high-performance, mass-producible microfluidic flow cytometry.
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA. junhuang@psu.edu.
authors.forename: Ahmad Ahsan
authors.initials: AA
authors.lastname: Nawaz
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaole
authors.initials: X
authors.lastname: Mao
authors.forename: Joseph
authors.initials: J
authors.lastname: Rufo
authors.forename: Sz-Chin Steven
authors.initials: SC
authors.lastname: Lin
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Zhao
authors.forename: Michael
authors.initials: M
authors.lastname: Lapsley
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: J Philip
authors.initials: JP
authors.lastname: McCoy
authors.forename: Stewart J
authors.initials: SJ
authors.lastname: Levine
authors.forename: Tony Jun
authors.initials: TJ
authors.lastname: Huang
mesh_terms: D005434:Flow Cytometry; D019793:Fluorescein / Q000737:chemistry; D057809:HEK293 Cells; D006801:Humans; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional; D044085:Microfluidics / Q000379:methods*
chemical_list: D019793:Fluorescein