# Optically trapped aqueous droplets for single molecule studies

Zach Wissner-Gross (May 2, 2009)

## Information

Optically trapped aqueous droplets for single molecule studies

J. E. Reiner, A. M. Crawford, R. B. Kishore, Lori S. Goldner, K. Helmerson

Applied Physics Letters, 2006, 89, 013904

## Soft matter keywords

Surface tension, optical trapping

## Summary

To optically trap microparticles, one requirement is that the particle have a higher index of refraction than its surrounding medium. While small plastics beads are easy to trap, water droplets are more difficult to to water's relatively low refractive index of 1.33. Reiner et al. overcome this difficulty by mixing water with a low-index (1.29) hydrophobic fluorocarbon medium, followed by ultrasonication to produce droplets approximately 2 $\mu$m in diameter.