Up to this point, painful injections were a reality for anyone receiving immunizations or flu shots; however, new developments from Seoul National University in South Korea have introduced the concept of laser injections. While the practice was formerly associated with cosmetic procedures, the researchers discovered that by using a longer pulse and adjusting to a wavelength best absorbed by water, they could create the optimal conditions for a delivering a shot that is only as painful as “a puff of air.”
Professor Jack Yoh, who led the study, explains how this is possible:
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. The image below shows the dispersion of medication without a target.
The laser that is used in the procedure (pictured below) is called an erbium-doped yttrium aluminium garnet, or Er:YAG. It propels a stream of liquid medicine through a piston-like nozzle (also pictured below) in a narrow jet, which measures 150 millionths of a meter in diameter. To give a point of reference, this is just slightly larger than the width of a single human hair. The force behind the injection is made possible by a membrane of water which converges with the medicine, creating a vapor bubble whose pressure propels the drug forward.
Because the jet has such a fine diameter, the medication will penetrate several millimeters beneath the skin surface, specifically into the epidermal layer, which has no nerve endings – making the injection a completely pain-free experience. In addition to the promise of eliminating unpleasant needle pricks, the technology carries the added benefit of cutting down on the amount of waste generated by single-use hypodermics.
Professor Yoh is now in the process of creating low-cost, replaceable injections for clinical use. He says,
In the immediate future, this technology could be most easily adapted to situations where small doses of drugs are injected at multiple sites. Further work would be necessary to adapt it for scenarios like mass vaccine injections for children.
To read a more detailed report of Yoh et. al’s research, their article, ‘Er:YAG laser pulse for small-dose splashback-free microjet transdermal drug delivery’, is published online in Optics Letters.
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