Er:YAG laser pulse for small-dose splashback-free microjet transdermal drug delivery.

The microjet injector system accelerates drugs and delivers them without a needle, which is shown to overcome the weaknesses of existing jet injectors. A significant increase in the delivered dose of drugs is reported with multiple pulses of laser beam at lower laser energy than was previously used in a Nd:YAG system. The new injection scheme uses the beam wavelength best absorbable by water at a longer pulse mode for elongated microjet penetration into a skin target. A 2.9 µm Er:YAG laser at 250 µs pulse duration is used for fluorescent staining of guinea pig skin and for injection controllability study. Hydrodynamic theory confirms the nozzle exit jet velocity obtained by the present microjet system.