Custom designed optical tweezer for trapping yeast cells

The goal of this study is developing custom designed optical tweezer which uses two
He-Ne lasers (λ=632.8 nm) parallel to each other to trap yeast cells. The
characteristic specs of this optical tweezer determined by Brownian Motion of
polystyrene beads in water. Stiffness and trapping forces of optical tweezer
calculated for laser 1, laser 2 and when both lasers used simultaneously. Laser 2 can
trap and move particle to laser 1 and multiple particles can be trapped by the laser 1.
After determination of specs of optical tweezer, yeast cells in yogurt culture medium
were trapped by laser 1 and laser 2. Stiffness of optical tweezer and trapping force on
yeast cells were determined by drag force and Brownian motion methods by
assuming the medium was homogenous and had viscosity of 0.038 kg/ms. Viscosity
depends on the concentration of fluid and surface. Viscosity of the yogurt culture
medium which was used in experiments was calculated theoretically with respect to
velocity of fluid and specs of optical tweezer calculated previously. Possibility of
application inside yeast cells was studied theoretically by using viscosity of
cytoplasmic medium. As a result of this study, this custom designed optical tweezer
which uses two He-Ne lasers are applicable in life sciences like inside cells, viscosity
measurements and drug delivery systems.