Laser injection less painful than needles Published duration 14 September 2012

image caption When microjet is fired from the laser, the liquid reaches the speed of 30m per second

A laser device for less painful injections has been developed by South Korean scientists.

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.

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.