3D-printed flexible mesh supports customization of prosthetic and implantable medical devices

Leveraging one of the game-changing capabilities of 3D printing, engineers at the Massachusetts Institute of Technology (MIT; Cambridge, MA) have designed pliable, 3D-printed mesh materials in which the flexibility and toughness can be fine tuned to support soft tissues such as muscles and tendons. The intricate mesh structures can be tailored to match individual anatomies in ankle and knee braces and even implantable devices, such as hernia meshes, according to a press release on the MIT website.

3D-printed flexible mesh developed at MIT
The 3D-printed flexible mesh structures can be tailored to match individual anatomies in ankle and knee braces and even implantable devices. Image courtesy Felice Frankel/MIT.

As a demonstration, the research team printed a flexible mesh for use in an ankle brace. They tailored the mesh’s structure to prevent the ankle from turning inward—a common cause of injury—while allowing the joint to move freely in other directions. The researchers also fabricated a knee brace design that could conform to the knee even as it bends and a glove with a sewn-in 3D-printed mesh that conforms to the wearer’s knuckles, providing resistance against involuntary clenching that can occur following a stroke.

“This work is new in that it focuses on the mechanical properties and geometries required to support soft tissues,” said Sebastian Pattinson, who conducted the research as a postdoc at MIT. Pattinson, now on the faculty at Cambridge University, is the lead author of a study published in the journal, Advanced Functional Materials.

“3D-printed clothing and devices tend to be very bulky,” said Pattinson. “We were trying to think of how we can make 3D-printed constructs more flexible and comfortable, like textiles and fabrics.”

Inspired by collagen

Inspired by the molecular structure of collagen, which makes up much of the body’s soft tissues and resembles “curvy, intertwined strands” under a microscope, Pattinson designed wavy patterns that he 3D-printed using thermoplastic polyurethane. He then fabricated a mesh configuration to resemble a stretchy yet tough, pliable fabric. The taller he designed the waves, the more the mesh could be stretched at low strain before becoming more stiff, a design principle that can help to tailor a mesh’s degree of flexibility and helped it to mimic soft tissue, explained the article on the MIT website.

The researchers tested the mesh on the ankles of several healthy volunteers. In general, they found the mesh increased the ankle’s stiffness during inversion (i.e., when the ankle turns inward), while leaving it relatively unaffected as it moved in other directions.

“The beauty of this technique lies in its simplicity and versatility. Mesh can be made on a basic desktop 3D printer, and the mechanics can be tailored to precisely match those of soft tissue,” said Associate Professor of mechanical engineering A. John Hart, who participated in the research.

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