3D Printer Body Parts

Humans can't regenerate lost body parts like some lizards and reptiles. (At least not yet, although some are trying.)

But with three-dimensional (3-D) printing, we can make them. And they can be identical to a missing appendage or custom-designed to fit any body. They can even make a bionic ear. Eat your heart out, Six Million Dollar Man.

The limbs made from 3-D printing are more flexible, more personalized, and more useful than past generations of artificial limbs, which were used mostly for cosmetic purposes, reports The Denver Post. The current generation of artificial limbs can act like clamps. They come with motors packed inside and electrical emitters embedded in the "muscles" of a forearm, allowing a hand to grasp, turn, and touch.

Artificial elbows can be printed that rotate toward the body, not just move up or down. These new joints could help a wounded veteran perform core functions, such as dressing, feeding, and medicating.

How Does 3-D Printing Work?

3-D printing is a process of making a three-dimensional solid object by a machine that lays down successive layers of material, often a powder or a polymer. The machine follows a virtual blueprint from CAD (computer-aided design) modeling software that "slices" the image into digital cross sections. The machine reproduces that "slice" onto successive layers.

It's like stacking quarters on top of one another. It's just that when you're done, the stack turns into a functioning golf club. Or, more specific to this article, the "stack" becomes an artificial limb or replacement cartilage for an ear.

A Finger in 16 Hours

Richard Weir, a research professor in the Department of Bioengineering at the University of Colorado School of Medicine, is using such a machine. The printer emits a laser-driven spark that melts a layer of metal powder a few microns thick. An arm like those found in photocopiers lays down another sheen of powder, and the laser then burns again. The process repeats for 16 hours -- et voila -- Weir and his graduate students pull out a custom-made finger for an artificial hand.

"It's a whole new way of thinking about how to make things," Weir says about 3-D printing. "Anthropomorphic shapes are a mess. Every person is different, and there are no right angles in a body. Once you have it in the computer, then you can play with it, do what you like with it."

Personalized Printing of Parts

The power of 3-D printing is that you can make what is not readily available. For example, a surgeon needed a specialized tool for a delicate operation on a child, and the 3-D printer made it. On another project, one of Weir's graduate students made a unique wrench, complete with a moving thumbscrew to open and close the crescent grip.

The potential uses of 3-D printers get researchers' creative juices flowing. Michael McAlpine, an assistant engineering professor at Princeton, has implanted electronics into a 3-D-printed human ear that could repair or even replace human ears, reports Design & Trend.

Building a Bionic Ear

The material for the bionic ear was a hydrogel seeded with calf cells. McAlpine added layers of silver nanoparticles to form a coil antenna. One end of that antenna connected to a system that simulated the cochlea, the part of the ear that allows humans to sense sounds.

In tests, the printed ear picked up radio waves. Ears on either side of a head could listen in stereo. The ear has the potential to attach to human nerve endings, but more tests are needed, he says.

Repairing Burned Skin With Polymers

A 3-D printer at the Wake Forest Institute for Regenerative Medicine makes cartilages, reports The Motley Fool. Researchers there used polymers and a solution of cartilage cells from a rabbit ear as the base material. They tested it by implanting it in mice. They hope that the innovation will eventually treat human knee injuries.

The scientists also printed skin cells and applied them onto burn wounds. In tests with mice, those injuries healed 40% faster than wounds that did not receive the new skin cells. Perhaps just to see what the printer could do, the researchers also built a three-dimensional kidney prototype.

In a related development, researchers at San Diego-based Organovo used a 3-D printer to print liver cells. These cells produced cholesterol and express enzymes, just like natural human liver cells.

Three-dimensional printing, combined with biological science, is generating a new era of one-of-a-kind design that puts custom medicine within reach.

image credit

Editor's Note: Dale McGeehon is the head blogger for Polymer Solutions Incorporated (PSI), a medical product testing lab with a history of solving complex challenges for medical device and pharmaceutical companies. Dale has been a journalist and editor for more than 25 years, and covers plastic testing and failure for the PSI blog.