A team of researchers at Seoul National University in South Korea have created a drug injection system that uses an Er:YAG infrared laser to propel liquid to about 70 mph (30 meters/sec). The stream is slightly wider than a human hair and, according to a study on guinea pigs, can penetrate skin to a depth of a few millimeters.
The device uses the laser to generate a high pressure vapor bubble within a small sack of water, causing the sack to rapidly expand. In turn, an adjacent compartment containing the liquid drug is forced to contract and release its cargo through a tiny nozzle. The team hopes their technology will soon lead to pain free injections and an end to aichmophobia in the clinic.
In previous studies, the 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. In the new work, Yoh and colleagues use a laser with a wavelength of 2,940 nanometers, which is readily absorbed by water. This allows the formation of a larger and more stable vapor bubble “which then induces higher pressure on the membrane,” he explains. “This is ideal for creating the jet and significantly improves skin penetration.”
Although other research groups have developed similar injectors, “they are mechanically driven,” using piston-like devices to force drugs into the skin, which gives less control over the jet strength and the drug dosage, Yoh says. “The laser-driven microjet injector can precisely control dose and the depth of drug penetration underneath the skin. Control via laser power is the major advancement over other devices, I believe.”
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 says. “Further work would be necessary to adopt it for scenarios like mass vaccine injections for children.”
Abstract in Optics Letters: Er:YAG laser pulse for small-dose splashback-free microjet transdermal drug delivery
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