Undergrads design safer suture needle

With the growing prevalence of people infected with transmissible diseases like HIV and hepatitis C, health-care providers are increasingly concerned about coming into contact with their patients’ bodily fluids. The greatest threat is accidental needle-stick injuries, especially from suture needles.

It’d be great if doctors, as they stitched up their patient’s wounds, could wear thimbles on their fingers, but they can’t for obvious reasons. A more effective solution would be a suture needle that’s sharp only when in use. No such device currently exists on the market, but the ingenuity of four UW–Madison undergraduate students could make the invention a reality.

As part of a senior design project for the biomedical engineering major, students Briar Duffy, Angela Heppner, Elizabeth Nee and Jeff Phillips decided to develop a safer suture needle, an idea they got from UW Hospitals and Clinics radiology professor Victor Haughton. The goal, says Duffy, was to find a way to deactivate the tip of the needle when it wasn’t stitching, thus minimizing the time the needle is sharp and the potential for injury.

The students thought the best design would involve some mechanism that could enable the curved needle to retract into a hollow sheath, where it would be guarded from accidentally poking somebody. Before they pursued this design, they researched the field – suturing techniques, properties of skin, prevalence of needle-stick injuries, suture needles on the market and even ones that had been patented but not yet developed.

“One of the best ideas for a safer suture needle had already been patented,” Duffy says. That version, which drew from a concept similar to the students’ design, included a metal trigger that could “arm” or “disarm” the sharp tip of the needle.

“When the group learned this,” says Mitch Tyler, a biomedical engineering researcher and the students’ mentor, “it really took the wind out of their sails. But I told them, ‘Just because there’s a patent doesn’t mean the game’s over.'”

While a suture needle similar to what the group hoped to design had been patented, the product had never been developed commercially. This meant the students could capitalize on the same idea but try to design a device that was technically simpler or cheaper to develop. The practical challenge of the biomedical engineering project, Tyler says, “is to design not just a laboratory widget but a marketable device.”

Still wanting to use the original concept of a self-disarming suture needle, the students began to brainstorm variations of the patented design. Early inspiration, Duffy says, came from “shoe bubbles” – the air pockets in sneakers that compress during movement. Drawing from that idea and their knowledge of physics, the group realized, however, a liquid-filled pocket would work better. Unlike air, Duffy explains, a liquid can’t be compressed into a smaller volume. For example, when you squeeze a water balloon, the balloon doesn’t get smaller – water inside moves around, changing the shape of the balloon.

Given this, the group thought that a fluid-filled balloon, when squeezed by the doctor’s tiny forceps that hold the needle during suturing, could push the needle out of the sheath, thereby arming the needle to stitch skin. After penetrating the tissue, the doctor would release the pressure on the balloon, causing the needle to retreat into the sheath.

With a budget of $600, the group started working on a prototype. To make the sheath, Duffy says they used PVC pipes with about one half-inch diameter that they bought at a hardware store. “We spray-painted them silver to make them look like stainless steel,” she adds. They made the needle out of a nail and the balloon from a pipette bulb.

But the group soon confronted a new challenge – friction. During design tests, the balloon rubbed against the sheath and wore down, possibly leaking fluid or even popping. Duffy says that “instead of a balloon, we’d like to make the sheath out of a memory metal,” which could quickly change its shape or volume in response to heat from the tissue being sutured. This design, Duffy adds, would have fewer parts than the group’s current one.

“At every step, the students encounter a new hurdle,” says Tyler, who describes himself as the team’s cheerleader, taskmaster, counselor and confidant. “I am continually astonished at how resourceful and resilient they are.”

After nearly two semesters of work, the group has corrected many flaws in the self-disarming suture needle that they call the JABE 200 – an acronym for the initials of each team member’s name, plus the number of hours they spent on the project before early December, when the liquid-filled balloon concept was developed. The group hopes the device can be patented through the Wisconsin Alumni Research Foundation, the organization that protects the intellectual property of UW–Madison’s faculty and students. “I never really thought of myself as an inventor before,” says Duffy.

“The prospect of a patent for their design project is pretty heady stuff for a 22-year-old,” mentor Tyler adds.

Regardless of the JABE 200’s future, two of the inventors will soon be heading to medical school. Duffy admits, “Jeff and I say to ourselves, ‘Wouldn’t it be funny if we’re in rounds one day, and a doctor holds up a new suturing needle that we designed as undergraduates!'”

To learn more about the JABE 200 or to see prototypes, visit the Undergraduate Research Symposium Thursday, April 18, beginning at 10 a.m. in the Memorial Union’s Great Hall (fourth floor), where UW–Madison students will showcase nearly 100 scientific, scholarly and service learning projects.