Austrian Biomechanical Engineer Designs 3-D-Printed ‘Keyhole’ Surgical Tool

A biomechanical engineer with the Austrian Center for Medical Innovation and Technology has developed a 3-D printed surgical tool that could change the way doctors analyze and remove cancerous tissues and perform what are known as “keyhole” operations.

The tool, designed by Filip Jelínek, is meant to be minimally invasive, and is aimed at improving the durability and manufacturability of medical instrumentation.

Working in collaboration with Paul Breedveld and Rob Pessers of Delft University of Technology in The Netherlands, Jelínek built the DragonFlex, a steerable, minimally invasive surgical instrument prototype. It looks like a pair of scissors, but procedures undertaken using the device cut recovery time for patients and leave less post-operative scar tissue behind, according to the Center.

Almost entirely 3D printed, the DragonFlex uses very few components to keep down manufacturing costs and limit assembly time. Jelínek believes the instrument can be marketed as a disposable, single-use product.

At just 5 millimeters wide, the DragonFlex prototype features a rolling joint with a special driving cable guide and a simple bolt-and-wheel mechanism for cable clamping and adjusting tension. The DragonFlex was made via additive manufactured from a ceramic-filled epoxy resin.

While the DragonFlex provides nearly equivalent functionality to other steerable laparoscopic instruments, constructing it with 3-D printing techniques provides a number of advantages, Jelínek said. “Using 3-D printing changes the way TU Delft researchers design,” he noted.

Only the tool’s cables and turnbuckles are made of metal. The DragonFlex instrument tip contains just a few parts, and it’s driven and bound by two cables mechanically fixed in the handle. Two ‘orthogonal planar joints’ feature a rolling link mechanism to let the cables to follow circular arc profiles of a diameter, which is 1.5 times larger than the width of the instrument shaft.

Aside from maximizing the lifespan of the cable, the rolling link was built to equalize the force requirements on both cables throughout the rotation of the joint. It makes handling fluid and effortless, and it also enables control of seven degrees of freedom, the Center said.

Two DragonFlex prototypes were developed using additive manufacturing technology, and they both allow grasping and omnidirectional steering over ± 90 degrees and feature high bending stiffness and extreme simplicity.

The orange prototype was printed by TNO (Eindhoven, The Netherlands) using a Perfactory SXGA+ Mini Multi Lens rapid prototype manufacturing system from a ceramic‐filled epoxy resin, EnvisionTEC NanoCure RCP 30, printed at 30μm resolution and 50μm layer thickness; the clear prototype was printed by PROFORM AG (Marly, Switzerland) using 3D Systems Viper si2™ SLA System from 3D Systems Accura 60, printed at 75±15μm resolution and 2.5μm layer thickness.