Biomedical Engineering

Trypanophobia. No, it's not the fear trying out a pan; it's the fear of needles. Well, more technically, it's the fear of a medical procedure which involves injections or hypodermic needles. I don't think anyone really likes getting a shot or having their blood drawn. But for some, like those with diabetes, a shot is part of their daily medicine regimen.

^{Image Credit:HealthWatchMD}

To the glee of every child (and grown-up children), researchers at MIT have recently engineered a device that delivers medicine into the skin without a needle. The device uses a tiny, high-pressure jet of medicine into the skin with the same amount of pain as a mosquito bite. The technology in the device allows for a range of doses to be delivered at various depths, which is a great improvement to similar jet-injection systems that are now commercially available.

Most of the current jet injectors don't have the mechanisms available to give different size doses of a drug and the injectors can only reach the same depth each time. The new device is built around a mechanism called a Lorentz-force actuator. This is a small, powerful magnet surrounded by a coil of wire that's attached to a piston inside a drug ampoule. As a current is applied, the coil of wire interacts with the magnetic field to create a force that pushes the piston forward. The drug is ejected at almost the speed of sound through air and with a high pressure through the ampoule's nozzle -- an opening as wide as a mosquito's proboscis (big word for the part that stings you). Check out this short video of the researchers explaining this technology.

^{MIT-engineered device injects drug without needles, delivering a high-velocity jet of liquid that breaches the skin at the speed of sound. Image courtesy of the MIT BioInstrumentation Lab}

The amount of current applied controls the speed of the coil and the velocity imparted to the drug. The MIT team generated pressure profiles that modulate the current, and the resulting waveforms consist of two distinct phases: an initial high-pressure phase in which the device ejects the drug at a high- enough velocity to "breach" the skin and reach the desired depth, then a lower-pressure phase where the drug is delivered in a slower stream that can easily be absorbed by the surrounding tissue. The device can be tailored to deliver the appropriate pressure based on the skin type of the patient (i.e., baby skin is easier to breach than adult skin).

^{A colored scanning electron microscope image of a female malaria mosquito's head shows its impressive array of olfactory sensors. The two feathery outer appendages are the antennae. The proboscis is in the middle, flanked by the maxillary palps that specialize in detecting odors coming from human hosts. Image Credit: Zwiebel Laboratory}

Another cool feature of the this new device is that it can deliver drugs that are generally in a powdered form by vibrating the device and turning the powder into a "fluidized" form that can be delivered into the skin like a liquid. The benefit of this feature is it reduces the need for vaccines to be refrigerated, making it easier to transport and deliver them into third world counties.

There are other significant benefits to this technology. Each year, there is an estimated 385,000 cases of hospital-based health care workers accidentally pricking themselves with needles. Using this needless device in hospitals will dramatically reduce that number. In home care, a device which removes the fear of needles will hopefully increase the rate of compliance among patients who have to regularly inject themselves with drugs such as insulin.

So even though needles don't scare me, I am excited about the prospect of never having to get one again.