Improving Precision in Catheter Lifecycle Testing with Integrated Servos

CONMED is a global medical technology company that specializes in the development and sale of surgical and patient monitoring products. Within their Research and Development (R&D) labs, engineers design sophisticated test fixtures to validate the reliability of life-saving medical devices, such as gastrointestinal (GI) catheters.

One critical testing protocol involves conditioning the electrical cables and Luer lock connections used in surgical procedures. To verify device longevity, a test fixture must screw and unscrew these connections approximately 1,000 times—simulating a full lifecycle of use—before the device is checked for functional integrity.

The R&D team originally utilized basic stepper motors to drive these cyclic tests. However, these systems lacked the ability to regulate or sense torque, which is a critical requirement for recreating ISO-standard Luer lock connections. Furthermore, the jerky motion common in low-cost stepper systems introduced variables that compromised the accuracy of force measurements.

"I was really looking for a motor that I could control the torque. That was the biggest thing," says Mike Bermingham, R&D Engineer at CONMED. "How I ended up with this motor was I wanted something where I could rotate to a certain torque and stop without having to use some sort of sensor... having the ability to have the motor read the torque and then adjust. I couldn't get that in one motor with [the previous system]."

Beyond torque control, the smoothness of the motion directly impacts the quality of the research data. "The smoothness is definitely a big thing," Bermingham explains. "A lot of our stuff is connecting two points... you're measuring very precise forces to make sure the device isn't going to fall apart in the body. If it’s not smooth—if there’s any sort of misalignment when it’s pulling—that can cause major differences in the force readings, drastically different measured values."

By transitioning to Teknic’s ClearPath-MC integrated servos, CONMED eliminated the need for separate external drivers and the complex wiring associated with multi-component motion systems. This all-in-one design allowed the R&D team to reduce the footprint of their test fixtures while increasing overall system reliability.

"The other motors I’m using all have to have separate drivers. It’s nice that everything’s kind of built into this motor. That’s definitely a great feature," notes Bermingham. "Having that separate thing, you have extra wires running... [the ClearPath] is way more heavy duty than I thought it was going to be."

In cyclic testing, the ability to return to the exact same position thousands of times is essential for establishing a baseline for mechanical wear. While previous systems struggled with displacement errors, the closed-loop performance of the ClearPath provided the repeatability necessary for medical-grade validation.