Thursday, April 11, 2013

Fiber-optic trap-on-a-chip platform for probing low refractive index contrast biomaterials

Tessa M. Piñón, Alessandro R. Castelli, Linda S. Hirst, and Jay E. Sharping
Dual-beam fiber trapping is a versatile technique for manipulating microparticles. We fabricate and evaluate the performance of a compact trap-on-a-chip design and demonstrate, for what we believe is the first time, trapping of low-contrast (m<1.005) lipid vesicles in solution. Counterpropagating fibers are fixed along the chip channel, and we calibrate the trap by optically displacing polystyrene microspheres from the trap center. Measured scattering forces are ∼30–49  pN from each beam. Stable trapping and reversible deformation of lipid vesicles is demonstrated under femtonewton trapping forces. This chip has applications in probing a variety of soft biomaterials, such as biological cells, lipid membranes, and protein assemblies.
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