3-D printing continues to improve the way doctors help their patients, as technological advances have made it possible for designers to create customized prosthetics, dental crowns and artificial tumors so doctors can get a closer look at the growth prior to surgery. Many of these devices are printed from solid or relatively inflexible materials as they often replace or support bones, but researchers are now turning the technology to soft tissues. Researchers at MIT have developed a pliable, 3-D printed mesh material that is both flexible and durable, and it could help patients in a number of different ways.
Developers envision the mesh as a supportive yet stretchy material that can be used in individualized, wearable supports for the ankle or knee. To showcase their innovation, researchers printed a flexible mesh ankle brace, a flexible knee brace, and a 3-D printed mesh glove. They designed the ankle brace to allow the ankle joint to move freely while also preventing against eversion sprains. The knee brace adapted to a person’s knee as it bent, and the glove was designed to prevent against involuntary clenching that can occur during 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 said the flexible mesh was inspired by the comfortable nature of clothes and trying to create a 3-D printed material similar to fabric.
“3-D-printed clothing and devices tend to be very bulky,” said Pattinson. “We were trying to think of how we can make 3-D-printed constructs more flexible and comfortable, like textiles and fabrics.”
They had the idea, but they didn’t have the plan to implement it until they got some inspiration from the human body in the form of collagen. Collagen is a structural protein that makes up many of the body’s soft tissues and is found in muscles, tendons and ligaments. Collagen’s design, when viewed under a microscope, looks like curvy, intertwined strands. These strands can straighten out when stretched, but when taut, extension becomes much harder. Essentially, it provides supportive yet restrictive mobility.
Inspired by this design, Pattinson designed wavy-patterned mesh. The taller the waves were, the more flexible the area of the mesh would be before it could stretch no more. Essentially, when the wave pattern was designed in a specific manner, it could allow limited flexibility in one area while allowing more movement in another area. When adapted to an ankle brace, it can help to ensure normal ankle joint movement while also providing less mobility in the ankle ligaments, which is a common cause of ankle sprains.
They then tested the mesh, and as hoped, the ankle exerted force as planned during 12 different movements, all without overloading an area that when stressed can lead to sprains. It won’t be surprising if customized ankle braces developed with 3-D technology become the norm in the not-so-distant future, but Pattinson concluded by saying it won’t just stop with ankles and knees.
“There’s potential to make all sorts of devices that interface with the human body,” Pattinson says. “Surgical meshes, orthoses, even cardiovascular devices like stents — you can imagine all potentially benefiting from the kinds of structures we show.”