Figure 3

Snapshots showing the trapping ability of the proposed spherical lenses on top of fibers for (A) a Mock tumoral cell, (B) a HST6 tumoral cell and (C) a Polystyrene particle as a target. (A–C)-I - The optical fiber tip is displaced towards the left (−x direction) (with the laser off) in relation to the target. (A–C)-II - The laser is turned on and the particle is attracted to the equilibrium position (trapping position) where it remains immobilized. (A–C)-III - The laser is again turned off and the fiber tip displaced towards the opposite transversal direction (towards the right, +x direction). (A–C)-IV - After the laser is turned on, the particle is displaced towards the right due to optical trapping forces. (A–C)-V - In order to study the longitudinal trapping forces profile for each particle type, the fiber tip is moved towards +y direction (down) with the laser off. (A–C)-VI - Particles are pushed after the laser is turned on. (A–C)-VII - The laser is turned off and the fiber tip is now moved along the longitudinal direction (towards −y, up). (A–C)-VIII - Particles are pulled due to optical trapping, excepting HST6 cells (cell movement due to trapping effects along -y direction are almost imperceptible, since the axial contribution of the gradient force to the total trapping force is negligible, in comparison with the transversal component of the gradient force, which plays the major role in the trapping phenomena).