Auckland Bioengineering Institute working towards a needle-free future

Imagine never having to get stuck with another needle again. A team at the University of Auckland’s Bioengineering Institute has developed an improved needle-free jet injector that could mean the end of scary injections.

14 November 2018

James McKeage, Jiali Xu and Kieran Brennan holding their needle-free jet injector.

Needle-free injectors aren’t new – they have been used for mass inoculation since the 70s. But they have always been limited by the amount of fluid they could inject.

“Needle-free injections are typically used to administer insulin and vaccines, because we’re talking very small volumes of fluid, up to 0.3 millilitres,” says Dr James McKeage, from the Institute’s Bioinstrumentation lab.

Our work has made it possible to deliver a whole millilitre using the same size injector, which means it can be also used for a wider range of applications, such as antibiotics and anaesthetics. Ultimately we could replace needles altogether.

Dr James McKeage

The team – which also includes Jiali Xu, Bahareh Madadkhahsalmassi, Nick Do and Kieran Brennan – are working on a range of improvements.

James and Nick are both looking at different methods of delivering more fluid.

James has designed a double-piston ampoule – the nozzle part on an injector – that is five times as efficient as current single-piston ampoules. It means more fluid can be injected using standard motors, but also that volumes of 0.3 ml can be injected using smaller, lighter motors.

At the same time, Nick has developed a permanent magnet linear synchronous motor which is four times as efficient as those currently used. His prototype can deliver 1ml of fluid and weighs only 600g.

“Because of the improved efficiency, we were also able to design a portable power supply that weighs less than 3kg,” says Nick.

“Ultimately, together with James’ work on the double-piston ampoule, we can easily increase the delivery volume to 2ml or even more.”

For most of us, the main drawback of using needles is that we just don’t like them.  But James says there are many other reasons to switch to needle-free injectors.

“A lot of diseases get accidentally transmitted in hospitals because of needles, like when a nurse or doctor accidentally sticks themselves. And that means the handling of disposed needles is a very expensive and time-consuming procedure.”

“In the third world, communities might not be able to afford enough needles, so if people have to choose between reusing a needle or not getting the injection, they will often decide to reuse,” says James.

The team is also working on a way to use a laser light to measure the depth that fluid is injected. Some medications are more effective at different depths.

Another idea is how to using injectors to measure the glucose levels of diabetics. If the injector could first take a blood sample, it would be possible to calculate precisely the right amount of insulin to deliver – all without the use of needles. This could be life-changing for diabetics.

“At the moment, diabetics have to inject themselves between two and five times a day with a needle, and each time is very painful,” says Bahareh. “Infection is another issue – if the diabetic cannot afford a lot of needles they will reuse the same one many times, which greatly increases the chance for infection.”

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