Optical Tweezers Research performed by: Rachel Patton McCord at The National Institute of Standards and Technology andDavidson College
Background: Optical Tweezers Physics • Balancing Forces: • Scattering Force- “Radiation Pressure” • Gradient Force- Restoring force analogy to spring Figure from: Svoboda and Block, 1994.
Physics, cont. • Tight focus = largest gradient force • obtained with microscope objective Images from: http://www.olympusmicro.com/primer/java/nuaperture/index.html
Basic Components Laser L1 L2 L3 Objective Lens f1 + f2 f3 16 cm Image created from Physlet at http://webphysics.davidson.edu/Course_Material/Py230L/optics/lenses.htm Physlet by Dr. Wolfgang Christian and Mike Lee
NIST Alignment • Gained experience with alignment by working on a two-laser trap setup.
Results Single Trap Both Traps Together
NIST Optical Tweezers Applications • Liposomes • Stretching/Nanotubes • Microreaction Vesicles • Single Mitochondria Isolation and Sorting • Available for PCR and genetic analysis • Antigen/Antibody Binding • Quantum Dots in Polymersomes • Fluorescence Resonance Energy Transfer and single molecule imaging
Results • Trapping microspheres in 3D • 10 mW minimum power from laser (about 2 mW at the slide) • Trapping single celled chlamydomonas Image from: http://www.ucmp.berkeley.edu/greenalgae/chlorophyceae.html
Future Plans • Force calibration • Measuring the swimming force of chlamydomonas • Flagellar mutants Further in the future: • Physics Applications • Stretching- elasticity, determining shear moduli • Biology Applications • More chlamy- phototaxis • Virus adhesion
Acknowledgments • Dr. Kris Helmerson, Jeff Wells, Lara Crigger, Rani Kishore, Joe Reiner at NIST • Dr. John Yukich and Dr. Karen Bernd