MIT research team develops needle-less injection device

The device can be programmed to deliver a range of doses to various depths, which is claimed to be an improvement over similar jet-injection systems that are now commercially available. 

In a statement the researchers say that among other benefits, the technology may help reduce the potential for needle-stick injuries. A needle-less device may also help improve compliance among patients who might otherwise avoid the discomfort of regularly injecting themselves with drugs such as insulin.

‘If you are afraid of needles and have to frequently self-inject, compliance can be an issue,’ said Catherine Hogan, a research scientist in MIT’s Department of Mechanical Engineering and a member of the research team. ‘We think this kind of technology… gets around some of the phobias that people may have about needles.’

Scientists have already developed alternatives to hypodermic needles; nicotine patches slowly release drugs through the skin but these patches only release drug molecules small enough to pass through the skin’s pores.

With the delivery of larger protein-based drugs on the rise, researchers have been developing new technologies capable of delivering them, including jet injectors, which produce a high-velocity jet of drugs that penetrate the skin. 

While there are several jet-based devices on the market today, Hogan said that there are drawbacks to these commercially available devices. The mechanisms they use, particularly in spring-loaded designs, release a coil that ejects the same amount of drug to the same depth every time.

The MIT team, led by Ian Hunter, the George N Hatsopoulos professor of mechanical engineering, has engineered a jet-injection system that delivers a range of doses to variable depths in a highly controlled manner.

The design is built around a mechanism called a Lorentz-force actuator — a small, powerful magnet surrounded by a coil of wire that’s attached to a piston inside a drug ampoule. When current is applied, it interacts with the magnetic field to produce a force that pushes the piston forward, ejecting the drug at very high pressure and velocity out through the ampoule’s nozzle.

The speed of the coil and the velocity imparted to the drug can reportedly be controlled by the amount of current applied; the MIT team generated pressure profiles that modulate the current.

The resulting waveforms generally 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.

Through testing, the group found that various skin types may require different waveforms to deliver adequate volumes of drugs to the desired depth.

‘If I’m breaching a baby’s skin to deliver a vaccine, I won’t need as much pressure as I would need to breach my skin,’ Hogan said. ‘We can tailor the pressure profile to be able to do that, and that’s the beauty of this device.’

The team reports on the development of this technology in the journal Medical Engineering & Physics.