Continuous flow two-dimensional acoustic orientation of nonspherical cells

Area of Science:

• Biomedical Engineering
• Cell Biology
• Analytical Chemistry

Background:

• Flow cytometry is crucial for cell analysis but struggles with nonspherical cells like red blood cells.
• Nonspherical cell orientation affects light scatter measurements, reducing analysis precision.
• Current methods lack precise control over nonspherical cell orientation.

Purpose of the Study:

• To develop a microfluidic chip for precise 2D focusing and orientation of red blood cells.
• To demonstrate controlled orientation of red blood cells using acoustophoresis.
• To improve the accuracy of flow and image cytometry for nonspherical cell populations.

Main Methods:

• A microfluidic chip utilizing ultrasonic standing waves for acoustophoresis.
• Two-dimensional focusing and orientation of red blood cells in the channel center.
• Controlled manipulation of cell orientation by adjusting acoustic energy in horizontal or vertical resonance modes.

Main Results:

• Achieved precise 2D focusing of red blood cells in the channel center.
• Demonstrated controlled orientation of red blood cells, with 87.8 ± 3.8% horizontally oriented and 98.7 ± 0.3% vertically oriented.
• Showcased the ability to orient cells to present specific sides toward the optical axis.

Conclusions:

• The developed microfluidic chip effectively orients nonspherical red blood cells with high accuracy.
• This technique offers a significant advancement for flow and image cytometry, particularly for analyzing challenging cell types.
• Controlled cell orientation has the potential to enhance the precision and capabilities of cytometric analyses.