Chinese hamster ovary (CHO) cell is the most widely used mammalian cell line for commercial production of therapeutic protein. Any presence of nonviable cells in culture medium may adversely affect subsequent functionality of these proteins. Therefore, separation of nonviable cells from suspending medium is critical in biopharmaceutical and biomedical sectors.  One such method termed Deterministic Lateral Displacement has already shown promising capabilities in separating cells based on the cell size difference by taking advantage of the predictable flow laminae. This passive separation system is generally composed of a set of micropost arrays within a microfluidic chamber that produce a force field at an angle (migration) to the flow direction. Separation occurs as a cell above a critical size but significantly less than the post gap size moves at a migration angle relative to fluid flow. However, in cases where size overlaps between viable and nonviable cells are present, separation based solely on size suffers and high resolution separation techniques are required. Dielectrophoresis, one of the most widely used nonlinear electro kinetic mechanism, has the potential to manipulate the same size cells depending on the dielectric properties of individual cells. When an inhomogeneous alternating electric field is applied to a cell, dielectrophoretic (DEP) force arises that depends on both the field frequency and cell dielectric properties. Therefore, cells with different dielectric characteristics will experience different DEP forces when subjected to such a field. By using suitable size post arrays, cells can be trapped or moved/redistributed between regions of high or low electric fields. In this work, a label-free CHO cell sorting is investigated based on the combination of DLD and dielectrophoresis approaches. We demonstrated that a DLD device can be combined with a frequency-based AC electric field to perform high resolution sorting of cells with different dielectric property even with overlapping sizes. Here, our proposed deterministic DEP device takes advantage of frequency-dependent AC electric field for continuous separation of nonviable CHO cells from the viable or productive cells. The behavior of the coupled DLD-DEP device is further investigated by employing numerical simulation to check the effect of geometrical parameters of the DLD arrays, velocities of the flow field and required applied voltages. A moderate row shift fraction with velocity 300µm/s provided a good separation behavior without any trapping. The cell viability was also ensured by maintaining proper electric field which otherwise may cause cell loss due to ion leakage. Our developed numerical model and presented results lay the groundwork for design and fabrication of high resolution DLD-DEP microchips for enhanced separation of viable and nonviable cells. 


Separation of Non-Viable Chinese Hamster Ovary (CHO) Cells Using Dielectrophoresis in a Deterministic Lateral Displacement Ratchet

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

IMECE2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.