Controlled rotation of cells using a single-beam anisotropic optical trap

Non-contact, noninvasive techniques to control the orientation of single living cells are highly valuable for biological research and clinical applications. We experimentally demonstrate a single-beam, single-fiber optical manipulation technique using an anisotropic, four-lobed light field propagated by low-order fiber mode LP21. The laser beam forms a rotationally non-axisymmetric optical multi-trap that may be directed to a spatial location on-demand, capable of cell translation, rotation, and orientation-holding with emitted power as low as 10 mW. We further developed a T-matrix based simulation method that can numerically model and optimize parameters that vary desired laser trap opto-mechanical properties, such as holding torque and capture efficiency. The demonstrated technique is easy to implement for cell micro-manipulation in complex research environments with multi-side occlusion, such as within a microfluidic channel in a lab-on-chip system, and may be used in conjunction with additional units for low-profile three-dimensional rotation and translation, or with other magnetic or electrical manipulation techniques.