Biological sample preparation is an important component for use in diagnostic testing and health monitoring with biosensors. Currently there is a push to make portable biosensors for Point of Care (POC) diagnostics as well as remote health care monitoring. As biosensors become more portable, biosample preparation needs to become more portable or integrate with biosensors to ensure that the testing process is not bottlenecked by the need for large scale sample preparation equipment.  The microfluidic-based techniques provide numerous advantages over conventional methods by miniaturization of necessary equipment and integration of complex protocols commonly associated with biosample preparation. Additionally, microfluidic techniques provide the ability for lower reagent use and faster process times. Specifically, deterministic lateral displacement (DLD) is a size-based separation technique with a strong potential for biosample preparation DLD uses an array of pillars to separate particles based on their critical diameter. Recently, it has been shown that symmetric airfoil shaped pillars with neutral angle-of-attack (AoA) can be used for high-throughput design of DLD devices due to their mitigation of pressure drop and preservation of flow symmetry under high Reynolds conditions. Increasing the flow velocity lowers the critical shift diameter of the system allowing for a variation of particle sizes to be separated based off the Reynolds number. The ability to change the critical shift diameter of the system by changing flow velocity, provides feasibility of DLD cell separation for multiple target biomarkers in one design.  Initial testing has been done in order to characterize particle trajectory in Deionized water particle solution at various Reynolds number. However, most biological fluids, such as blood, are non-Newtonian, and therefore the viscosity of the fluid is subject to change. In order to design a DLD device for use with biological fluids, particle trajectory at a range of viscosities needs to be characterized. We have tested two DLD models with polystyrene particles at various viscosities and Reynolds numbers to characterize particle trajectories. Both devices use airfoils, one with a negative AoA, and the other with Neutral AoA relative to direction of liquid flow. Variations in Particle suspension viscosities are created by mixing glycerol with DI water and altering the solution ratio between tests. The data shows that particles in the glycerol DI water suspension are following the same trend based off Reynolds number as the particles tested in a DI water suspension. Additionally, the negative AoA provides increased negative particle trajectory at lower flow rates and can help negate device failure due to the higher pressure with an increase in viscosity.


Airfoil Deterministic Lateral Displacement for High-Throughput Particle Separation in Viscous Fluids

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

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