September 13, 2012

Pain-Free Laser Flu Shots Could Be The Future

Lee Rannals for — Your Universe Online

Afraid of a shot? Well, the future is either going to annul that fear, or make it ten times worse if you´re afraid of lasers, too.

A new laser-based system is capable of basting drugs into the skin, but making it as painless as being hit with a puff of air. The only fear to get over at that point is the idea of a laser instead of a needle.

The new system uses an erbium-doped yttrium aluminum garnet (Er:YAG) laser to propel a precise stream of medicine with just the right amount of force.

Dermatologists commonly use this laser already, particularly for facial aesthetic treatments.

The laser is combined with a small adapter that contains the drug to be delivered, as well as a chamber containing water that acts as a "driving" fluid.

A flexible membrane separates these two liquids, and each laser pulse generates a vapor 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 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," Jack Yoh, professor of mechanical and aerospace engineering at Seoul National University in South Korea, who developed the device along with his graduate students, said in a statement.

The researchers tested the device on guinea pig skin, which showed that the drug-laden jet could penetrate up to several millimeters beneath the skin surface, with no damage to the tissue.

In past studies, researchers used a laser wavelength that was not well absorbed by the water of the driving liquid, causing the formation of tiny shock waves that dissipated energy and hampered the formation of the vapor bubble.

During the new study, Yoh and his team used a laser with a wavelength of 2,940 nanometers, which is readily absorbed by water. This allowed the formation of a larger and more stable vapor bubble.

"This is ideal for creating the jet and significantly improves skin penetration," Yoh said in the statement.

Other similar injectors are piston-like devices that force drugs into the skin, giving doctors less control over the jet strength and the drug dose.

"The laser-driven microjet injector can precisely control dose and the depth of drug penetration underneath the skin," Yoh said. "Control via laser power is the major advancement over other devices, I believe."

The team 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," Yoh said in the statement. "Further work would be necessary to adopt it for scenarios like mass vaccine injections for children."

The paper describing the injector was published in the Optical Society's journal Optics Letters.