In this paper it is attempted to have a closer understanding of a cell when it is subjected to a highly focused laser beam giving a special attention to a single ionized cell during its pre-ionization phase. Cells of varying size are subjected to a 1064nm near infrared (NIR) radiation one by one and their trajectory (radial and tangential) towards the center of the trap has been recorded and analyzed. The result showed that the cells gain charge even before being trapped by the trapping center i.e. while they are on their way to the center. As a result, the charged cells have been observed interacting with the electromagnetic field creating a Coulomb force in the direction of polarization. Consequently, the developed charge significantly affected the trajectory of each cell towards the trap center by retarding those cells whose gradient force vector and direction of polarization are in opposite direction while accelerating those cells whose gradient force vectors align to the direction of polarization.
Keywords: laser trapping, gradient force, single-cell ionization, pre-ionization stage, ionization-stage, post-ionization stage.