Those of us with an aversion to needles can soon go to the doctor with a little less trepidation. That is if a new device developed by a team of MIT researchers becomes available at your local medical facility. The device uses a Lorentz-force actuator to create an adjustable high-pressure jet that is ejected out of a nozzle as wide as a mosquito's proboscis, penetrating the skin to deliver highly controlled doses at different depths.
While jet-injectors have been commercially available for decades, they typically rely on compressed air or gas cartridges to power each delivery. The Lorentz-force actuator - a small, powerful magnet surrounded by a coil of wire that's attached to a piston inside the drug ampoule - is powered by an electric current. Able to pressurize a drug up to 100 megapascals in under a millisecond, the device is capable of injecting high pressure doses at almost the speed of sound in air, (about 314 m/s or 1,126 ft/s). By altering the electric current, the velocity of the delivery can even be changed mid-injection.
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To modulate the current and velocity of a delivery, the MIT team has generated various pressure profiles for the device. These generally include two distinct phases - a high-pressure phase to breach the skin and reach the desired depth, followed by a lower-pressure stream that allows the medicine to be absorbed by the surrounding tissue. The pressures can also be modified to suit different skin types.
“If I’m breaching a baby’s skin to deliver vaccine, I won’t need as much pressure as I would need to breach my skin,” says Catherine Hogan, a research scientist in MIT’s Department of Mechanical Engineering. “We can tailor the pressure profile to be able to do that, and that’s the beauty of this device."
Another of the many advantages this method of drug delivery offers over the old hypodermic syringe is that it can reduce the potential risk of accidental needle-stick injuries. The Centers for Disease Control and Prevention estimates that about 385,000 accidental needle-stick incidents occur each year among hospital-based health care workers in the U.S.
People with an aversion to needles will also find it easier to get shots. The creators at MIT point out that this is especially true for people who have to give themselves injections on a regular basis.
"If you are afraid of needles and have to frequently self-inject, compliance can be an issue," says Hogan. "We think this kind of technology … gets around some of the phobias that people may have about needles."
Engineers working on the project are already looking at innovative methods of delivery, beyond injecting medicine into a patient's upper arm. The MIT engineers have tested the ability to deliver drugs right through the eye to the retina, and also through the tympanic membrane (or eardrum) to deliver drugs to the middle and inner ear.
Ian Hunter, the George N. Hatsopoulos Professor of Mechanical Engineering who led the research team, says the device can also take a drug in powdered form and be programmed to vibrate at such a rate as to make the drug behave like a liquid as it is injected into a patient. Unlike vaccines in liquid form that often need to be refrigerated, powdered drugs require no cooling, making them easier to deliver in developing countries.
The new device developed by the MIT team is described in the journal Medical Engineering & Physics.
Here’s Hunter and Hogan describing their new jet-injection technology.