Abstract
When an intense infrared femtosecond laser is focused inside an aqueous solution through an objective
lens, shock and stress waves are generated at the laser focal point after effective multi-photon and
excited-state absorptions. These waves propagate from the laser focal point and act in its vicinity with
biological cells as an impulsive force, which we applied to manipulate animal and plant cells. In this
review, we explained a photo-excitation mechanism at the laser focal point and indicated an advantage
of the femtosecond laser-induced impulsive force in comparison with other pulse lasers. We observed
the behaviors of animal and plant cells with impulsive force action by high-speed imaging and
interpreted their differences from the mechanism to protect the cell from external force.
