Laser-powered 'needle' for pain-free injections

Laser-powered 'needle' for pain-free injections

Scared of injections? A new laser-based system that makes a jab as painless as being hit with a puff of air has been developed.

South Korean scientists have developed a new system that blasts microscopic jets of drugs into the skin making an injection a painless affair.

The system developed by the Seoul National University uses an erbium-doped yttrium aluminium garnet, or Er:YAG, laser to propel a tiny, precise stream of medicine with just the right amount of force.

“This type of laser is commonly used by dermatologists, “particularly for facial aesthetic treatments,” Jack Yoh, lead researcher said.

The laser is combined with a small adaptor that contains the drug to be delivered, in liquid form, plus a chamber containing water that acts as a “driving” fluid.

A flexible membrane separates these two liquids. Each laser pulse, which lasts just 250 millionths of a second, generates a vapour bubble inside the driving fluid.

The pressure of that bubble puts elastic strain on the membrane, causing the drug to be forcefully ejected from a miniature nozzle in a narrow jet a mere 150 millionths of a metre (micrometres) in diameter, just a little larger than the width of a human hair.

“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,” Yoh said in a statement.

Tests on guinea pig skin show that the drug-laden jet can penetrate up to several millimetres beneath the skin surface, with no damage to the tissue.

“Our aim is the epidermal layer,” which is located closer to the skin surface, at a depth of only about 500 micrometres. This region of the skin has no nerve endings, so the method will be completely pain-free,” he said.

Yoh is now working with a company to produce low-cost replaceable injectors for clinical use. “In the immediate future, this technology could be most easily adopted to situations where small doses of drugs are injected at multiple sites,” he said.

“Further work would be necessary to adopt it for scenarios like mass vaccine injections for children,” he added.

The injector was described in a paper published in the Optical Society’s (OSA) journal Optics Letters.