Laser injection less painful than needles

The system could replace traditional needles, with a jab as painless as being hit with a puff of air. The laser is already used in aesthetic skin treatments. The aim now is to make low-cost injectors for clinical use.
A team from Seoul National University in South Korea describe the process in the Optical Society’s journal Optics Letters.
The researchers write that the laser, called erbium-doped yttrium aluminium garnet, or Er:YAG, propels a stream of medicine with the right force to almost painlessly enter the skin.
The jet is slightly larger than the width of a human hair and can reach the speed of 30m (100ft) per second.
"The impacting jet pressure is higher than the skin tensile strength and thus causes the jet to smoothly penetrate into the targeted depth underneath the skin, without any splashback of the drug," said Prof Jack Yoh of Seoul National University, who led the study.
Piston-like injectors are already in use, but jet strength and drug dose are more difficult to control.
"The laser-driven microjet injector can precisely control dose and the depth of drug penetration underneath the skin," said Prof Yoh.
The scientists have tested the laser on guinea pigs, injecting the drug up to several millimetres beneath the skin without any damage to the tissue, and are starting work on injectors for clinical use.