PRINCETON, N.J. -- With a 3-D printer, a petri dish and some cells from a cow, Princeton University researchers are growing synthetic ears that can receive -- and transmit -- sound.
The scientists send bovine cells mixed in a liquid gel through the printer, followed by tiny particles of silver. The printer is programmed to shape the material into a "bionic ear," and forms the silver particles into a coiled antenna that can pick up radio signals that the ear will interpret as sound.
The 3-D ear is not designed to replace a human one, though; the study is meant to explore a method of combining electronics with biological material.
"What we really did here was actually more of a proof of concept of the capabilities of 3-D printing," said Michael McAlpine, the professor who led the project. "Because most people use 3-D printing to print passive objects -- things like figurines and jewelry."
After it's printed, the 3-D ear is soft and translucent. It is cultivated for 10 weeks, letting the cells multiply, creating a flesh color and forming hardened tissue around the antenna.
McAlpine and his team demonstrated the antenna's ability to pick up radio signals by attaching electrodes onto the backs of the ears in the printing process.
When they broadcast a recording of Beethoven's "Für Elise" to a pair of fully cultivated ears, the electrodes transmitted the signal along wires to a set of speakers, and the music flowed out clearly.
McAlpine said the research could lead to synthetic replacements for actual human functions, and to a sort of electronic sixth sense.