You may not want to face this fact if you’re afraid of needles, but it’s a simple truth: In the course of treating the spectrum of human medical conditions, doctors are often forced to stick large needles deep inside your body (they will claim to get no pleasure out of this, surely). The problem is that your body is pretty tightly jam-packed with important items and needles are straight and rigid, which means it can often be hard to avoid piercing other things on the way to your target. But now flexible needles with asymmetric tips can chart arced paths through the body, swerving past organs and dodging dense tissue. This tech could one day expand the reach of minimally invasive surgeries.
The needles are being designed at a Stanford robotics lab headed by Allison Okamura. They’re made of nitinol, a shape memory alloy, and bore through the soft tissue of the body spinning like a drill bit. "They’re very bendy, not squishy," Okamura clarifies. A needle made of nitinol is hard to touch, but can bend to outrageous angles without breaking or permanently changing shape. "You could wrap it around your finger if you wanted to," Okamura says.
As the shape of the needle tip is changed, it alters the backward pressure the needle tip faces as it plunges through the body, and so alters the curvature of the path the needle takes. This added dexterity opens up the possibility, Okamura says, for surgeons to one day perform minimally invasive procedures that they otherwise hadn’t considered.
One of the early applications that the lab is testing is a form of radiation treatment for cancer patients called brachytherapy, one of the tools oncologists call on to treat prostate cancer. The technique involves threading radioactive beads through a needle and planting them in cancerous locations in the prostate tissue. The beads deliver radiation to a very specific area, minimizing damage to the urethra and other organs.
Flexible needles could move around more easily than rigid ones, so the idea, Okamura says, is to use just one needle instead of several. That wouldn’t be too big a departure from the way brachytherapy is performed today—but for the patient, it could make a huge difference. "Imagine having 50 needles stuck through your bottom side versus, you know, one," Okamura says. "It could be a huge advantage for the patient there."
The group recently tested the needles on canine tissue samples—from extracted organs like the liver and kidneys—as well as in organs in a live, anesthetized dog. Okamura’s goal is also to test needle steering for surgeries that don’t have a minimally invasive option today. "The other possibility is: Let’s look at procedures no one’s ever dreamed of doing without the body open, because you couldn’t get that kind of dexterity inside the body before."
The ultimate goal, one that’s a long way away, is to hand over these precise tools to robotic surgeons. For now, the group is working with human surgeons to carry out more advanced tests, and applying for approval to shepherd them through clinical trials.