Optical Trapping and Manipulation of Microbes Using Laser Tweezers
Ruili Wang
Georgia State University
Abstract
Optical radiation pressure forces will be discussed and the conditions
to obtain optical trapping will be summarized. Optical trapping and manipulation
of neutral particles using a He-Ne laser and an Argon ion Laser are presented.
Microbes are used to demonstrate optical trapping and manipulation, and
to understand the laser trap function and limitations for biological objects.
Nine kinds of microbe samples with different cultural periods and conditions
were used. Trapping and manipulating procedures for single living biological
cell and spores using a single beam optical trap constructed by a laser
coupled into a microscope will be demonstrated. The rotation of particles
trapped in laser tweezers was observed. The average transverse trapping
speed is in the range of micrometers to tens of micrometers per second.
The comparison and analysis of experimental results indicate that the optical
forces exerted on the biological samples are dependent not only on laser
power, wavelength, convergence angle and spot size, but also the cultural
periods and
conditions which are highly related to the optical properties of biological
samples trapped. In addition a simulation of the manipulation of organelles
within a cell will be demonstrated using a physical model. We will show
the manipulation of subcellular organelles, such as chloroplasts and protoplasts
of tobacco young leaf cell. The experiments provide many useful hints and
foundations for laser tweezer applications.