Researchers must be able to rotate individual cells to image them in three dimensions, which yields measurements of their surface area, roughness, and volume. However, most existing techniques for rotating cells are either too complex or not precise enough, and they usually only rotate a cell on one axis.

Mao et al. developed a simple technique to rotate a cell on multiple axes. In this method, an optical tweezer, a laser-based instrument, holds a cell in place in asymmetric flow fields. The asymmetry of the surrounding flow causes the cell to rotate.

Adjusting the focal position of the optical tweezers to position a cell in various flow profiles changes the rotation speed, direction, and axis of the cell. This elegantly uncomplicated approach achieves the desired control and rotation flexibility.

“The technology we reported is simple. It can achieve high-precision multi-axis rotation control without the need for complex components and control mechanisms and with minimal damage to the cell,” said author Zhensheng Zhong. “It is of great potential in rapid and high-precision cell surface and volumetric imaging.”

The authors demonstrated the power of this technique by analyzing the surface of differently shaped red blood cells. By rotating the cells to image them at various angles, the researchers were able to reconstruct their surface morphology in 3D. They measured cell surface area, volume, sphericity, and roughness from these images, demonstrating the potential of this technique in cellular morphological analysis.

Next, the authors will study the accuracy of the rotation control of this technique and combine it with other imaging methods, such as quantitative phase imaging and fluorescence imaging.

Source: “Optofluidic-based cell multi-axis controllable rotation and 3D surface imaging,” by Yuxin Mao, Songlin Li, Zixin Wang, Meng Shao, Peng Wang, Xinyuan Tan, Fengya Lu, Yi Wang, Xunbin Wei, Zhensheng Zhong, and Jinhua Zhou, Applied Physics Letters (2023). The article can be accessed at