SEMINAR @ SISSA, SBP, dr. Cojoc 16/06/06 at 9.00 a.m.

[Barbara Corzani]

********************************************************************
STATISTICAL AND BIOLOGICAL PHYSICS SEMINAR
*********************************************************************


Dott. Dan Cojoc
(Tasc - Lab. Nazionale di tecnologie avanzate e nanoscienza 
c/o Sincrotrone)

Title:
"Optical trapping and manipulation of living cells"


Fri. 16  June 2006  @ 9.00 a.m.


SISSA - Basement floor - room A

********************************************************************

Abstract:
Since their invention in the eighties, laser tweezers techniques have been extended from trapping silica microbeads to trapping  and manipulation of a wide range of samples, as material (metallic, low-index, biological), shape (spherical, cylindrical, arbitrary) and size (5 nm to 20 ?m).  

In this seminar, we discuss the use of laser tweezers for direct and indirect manipulation of living cells. One of the most exciting developments in recent years has been the creation of two- and three-dimensional arrays of optical traps by using diffractive optical elements (DOEs) implemented on spatial light modulators (SLMs) . We have developed our own algorithms and codes to design phase DOEs that can transform a single laser beam into an array of independent traps, each with individually specified characteristics, arranged in various geometrical configurations. Manipulation of multiple particles, directly trapped by the beam, can be achieved using the dynamic displaying of the SLM. Indirect trapping and manipulation of the sample can be obtained surrounding it with trapped micro beads that are manipulated by the optical tweezers. In this case the laser light is not directly focused on the sample but is distributed on the beads and therefore the photo-induced damaging of biological samples is reduced. 

Some examples of optical manipulation are presented and discussed: cell arraying and sorting, cell trapping and orientation for micro Raman spectroscopy experiments, cell mechanical stimulation with pN controlled forces.