Scientists at Washington State University are creating waterjet-based, steerable needles that could give doctors more accuracy and control and reduce tissue damage in many common, non-invasive medical procedures.

John Swensen, an assistant professor in the School of Mechanical and Materials Engineering, and graduate students Mahdieh Babaiasl and Fan Yang were part of a WSU team that recently co-authored a paper on steerable needles, which was published in the 2019 International Symposium on Medical Robotics (ISMR)

“Our needles have the potential to improve treatments that you can’t reach with traditional straight needles,” Babaiasl said.

For many medical procedures, doctors would like to have bendable, steerable needles to get to their targets. In fact, in a little trick of the trade, doctors will sometimes bend their needles by hand when trying to access a tricky spot, such as when giving a nerve block for back pain. Another problematic procedure for doctors is liver biopsies. When the area to be biopsied lies under the lungs, for instance, the needle must go through the chest cavity.

Waterjet technology has been used for decades in many industries, such as mining and manufacturing.

Swensen’s team developed a technology that uses a controllable waterjet nozzle at the tip of the needle to delicately cut through tissue. After the tissue is cut by the water jet, the bendable, flexible needle can follow the tissue fracture to its destination. In their study, the researchers looked at how the waterjet-based system performed using different nozzle widths, water pressures, and with different tissue stiffness. They recently filed for a patent.

Researchers testing a waterjet-based steerable needle. Their technique could decrease time taken for procedures, in some cases reducing the time taken for procedures by more than half. In addition, the accuracy generated by this technology means the needles can cut through tissue while keeping surrounding blood vessels intact.

In addition to allowing doctors to make turns, the waterjet needles create less friction than straight needles and cause less buckling of the needle and tearing of the surrounding tissue. Check out a video of the needle in action.

In the future, a nurse or doctor sitting in another room could control the needles with something like a video game console, Swensen said.

“Such needles also reduce the need to have precise manual hand-eye coordination,” he added.

Swensen and his team are currently testing their needle technology on artificial tissue made from an elastic polymer that mimics many of the physical properties of biological tissues and will soon begin experiments on real tissue.