Applied Physics

Harnessing Light Beams

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Science  19 Jan 2001:
Vol. 291, Issue 5503, pp. 399
DOI: 10.1126/science.291.5503.399b

The ability to manipulate microscopic particles with well-defined light fields led to the development of optical tweezers, which can be used to capture and move particles and even cells. Rotation of particles, a useful feature for gaining information about the fluid in which the particle is immersed, can be achieved by designing particular light-field gradients or by careful design of the microstructured device itself. For example, microstructured propellers will rotate when placed in the path of a light beam, in much the same way a windmill rotates in a breeze. As shown by Galajda and Ormos, careful design can also allow complex light-driven machines to be realized. Using a photosensitive resin, they sculpt freestanding, three-dimensional rotors and show that such propellers or turbines can be integrated into more complex devices. As an example, they prepare a light-driven gearing system involving a series of meshed rotors, which can serve as the basis for microscale pumps, switches, and machinery. — ISO

Appl. Phys. Lett.78, 249 (2001).

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