Optical tweezers are perhaps most well-known for their ability to make precise measurements of small forces and displacements, but they are also capable of high-speed and long-distance motion. High speed and long distance optical manipulation is necessary for high throughput in applications such as tissue engineering, cell sorting, and the assembly of 3D structures and materials. Here we present the greatest speeds that we have achieved using 3D optical traps to manipulate a variety of particle materials and sizes across millimeter-scale translation distances [1]. In general, higher laser powers enable faster manipulation speeds, and we investigate the high-speed / high-power limit of this relationship. For polystyrene microscale particles with diameters in the range 0.5 µm – 5 µm, we find that we are limited by mechanical stage vibrations to maximum speeds of ~220 µm/s, while for nanoscale gold, silver, and polystyrene particles, we are limited by thermal absorption effects to maximum speeds of 150 µm/s – 170 µm/s. In the low-power regime, we find good agreement with standard theory based on the balance of the optical gradient force with Stokes’ drag. Our results are, to the best of our knowledge, one of the most comprehensive studies of maximum particle manipulation speed, and we have attained the fastest published submicron particle manipulation speed. We think that these results will establish and highlight the high throughput potential for automated pick-and-place processes based on optical tweezers.
[1] J. E. Melzer and E. McLeod, ACS Nano, in press (2018), doi: 10.1021/acsnano.7b07914.
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