Method for optoinjection of exogenous material into a cell

Method for the optoinjection of exogenous material in a recipient biological cell enclosed by a membrane, which comprises: placing a biological cell on a planar surface of a substrate, transmitting a sub-ns pulsed laser beam through a variable convergence/divergence collimator, the collimator comprising a lens with focal length tunable by means of a variable amplitude control electrical signal; focusing the laser beam in a focal spot positioned along an axial direction substantially perpendicular to the substrate; moving the focal spot towards the cell along the axial direction by continuously varying the electric control signal from a first amplitude value corresponding to a first axial position zi of the focal spot above the apical surface of the cell to a second amplitude value, the second amplitude value defining a second focal length corresponding to a second axial position Zf of the focal spot, wherein the second amplitude value of the control signal is selected such that the second axial position is positioned inside the cell, at a second axial distance from the planar surface of the substrate, such that the focal spot traverses the membrane of the cell during the descent of the focal spot towards the cell producing a pore in the membrane, which allows the fluid solution containing exogenous material to enter the cell