A 3-D printer created a "bionic ear" able to hear frequencies far outside a human's detectable range.
The research team originally set out to explore merging electronics with tissue. They used an internet-purchased printer to create cells and nonoparticles, they then combined a coil antenna into cartilage, according to a Princeton University press release.
"In general, there are mechanical and thermal challenges with interfacing electronic materials with biological materials," said Michael McAlpine, an assistant professor of mechanical and aerospace engineering, who led the study, said.
"Previously, researchers have suggested some strategies to tailor the electronics so that this merger is less awkward," he said. "That typically happens between a 2-D sheet of electronics and a surface of the tissue. However, our work suggests a new approach - to build and grow the biology up with the electronics synergistically and in a 3-D interwoven format."
This is the team's first attempt at making a fully functioning organ, especially one that exceeds human ability.
"The design and implementation of bionic organs and devices that enhance human capabilities, known as cybernetics, has been an area of increasing scientific interest," the team wrote in an article.
Creating an 3-D ear from scratch is a complicated process which includes "seeding types of cells, such as those that form ear cartilage, onto a scaffold of a polymer material called a hydrogel." The team decided to try using a printer instead.
The printer creates 3-D objects form very thin layers of all types of materials, including cells. The device allowed them to combine the coil within in the ear itself, an extremely complex process. The calf cells used to create the ear eventually became cartilage.
Bridging the gap between tissue and electronics is extremely difficult, and must be mastered before "smart" prosthetics can be applied.
"Biological structures are soft and squishy, composed mostly of water and organic molecules, while conventional electronic devices are hard and dry, composed mainly of metals, semiconductors and inorganic dielectrics," he said. "The differences in physical and chemical properties between these two material classes could not be any more pronounced," David Gracias, an associate professor of chemical and biomolecular engineering at Johns Hopkins University who participated in the study said.
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