Controllable Cellular Micromotors Based on Optical Tweezers

Abstract

Micromotors hold exciting prospects in biomedical applications but still face a great challenge. To date, there have been few reports of micromotors with high safety, flexible controllability, and full biocompatibility. Here, a multifunctional method based on an optical tweezer system is presented to realize controllable cellular micromotors. The method not only satisfies all of the above criteria but is also independent of the cell types and materials. Optical tweezers are used to generate a dynamic scanning optical trap along a given circular trajectory, which can trap and drive a microparticle or a single cell to move along the trajectory and thus generate a microvortex. Cells within the microvortex will be controllably rotated under an action of shear stress or torque and their rotation rate and direction can be controlled by changing the scanning frequency and direction of the dynamic optical trap. The proposed method is effective for both immotile target cells and swimming target cells. Additionally, it is further applied to realize synchronous translation and rotation of cellular micromotors and to assemble controllable and fully biocompatible cellular micromotor assays. The proposed method is believed to have potential applications in targeted drug delivery, biological microenvironment monitoring and sensing, and biomedical treatment.

Reversible Design of Dynamic Assemblies at Small Scales

“…This was also shown for combinations of optical and electrical fields. [158] Moreover, testing the response of novel shapes and materials to diverse external fields could result in an ever-expanding library of potential building blocks. As the field moves toward increasingly complex assemblies at small scales, it will become important to embrace machine learning and artificial intelligence toward advancing parallel object tracking, feedback loops, and real-time remote control.…”

“…Reproduced with permission. [ 158 ] Copyright 2020, Wiley‐VCH. b) Use holographic optical tweezers to build 3D cellular microassemblies.…”

Initiating revolutions for optical manipulation: the origins and applications of rotational dynamics of trapped particles

“…Dynamic beam steering and shaping devices such as digital micromirror devices and spatial light modulators allow the creation of essentially any motion by dynamic manipulation of the position of optical traps. Apart from the trivial example of a particle trapped in a moving spot that describes a circular orbit [60], orientation and rotation of a particle can also be [70]. Copyright (2002) by the American Physical Society.…”

“…Vortex flows in the medium can be generated by particles orbiting around a circular trajectory. Zou et al [60] used a scanning optical tweezers setup to drive particles and cells along a circular trajectory, within which a microvortex was created which was able to spin multiple cells simultaneously (Figure 6(b)). In this case, the orbiting motion of a single rotor is converted into spinning motion of the targeted entities, which would be very difficult to accomplish using spinning rotors or other means.…”

Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

“…We show, in an experiment, that single descents can be used to calibrate the optical trap where large trap strengths restrict the performance of equilibrium measurements as they are in a regime where the signal is too close to the detection noise floor. This type of calibration is ideal for multiple and dynamic optical traps to rapidly determine the swimming forces of optically driven micromachines, active matter, and cells on the two micron size scale [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”