Engineers produce bionic ear able to pick up radio frequencies

Breakthrough technique melds electronics, cartilage with 3D printing

Researchers at Princeton University have developed a bionic ear using 3D printing. The ear is made of cells interwoven with electronics, and can pick up radio frequencies beyond the range of a human capabilities.

Michael McAlpine, leader of the project and assistant professor of mechanical and aerospace engineering at the university, said that in principle the bionic organ could be used to restore hearing in people. But he added that there is still further research and extensive testing to do before the technology could be used in this way.

The ear comprises of a coiled antenna embedded in a structure of cartilage cells that mimics the anatomy of the human ear. Electrical signals produced by the system in response to radiowaves could be used to stimulate a patient's nerve endings, in a similar way to a conventional hearing aid.

McAlpine and his team first made CAD drawings of the bionic ear to create the device. Next, they loaded cartilage cells, a biodegradable scaffolding material and conductive polymer infused with silver nanoparticles into an off-the-shelf 3D printer and printed the ear according to the CAD drawings. Once created, the researchers put the structure in a petri dish containing nutrients to allow the cells to grow.

They also created a complementary ear by reflecting the original CAD drawings to make a pair. The function of the ears was tested by transmitting Beethoven's Fur Elise through a magnetic loop antenna. Electrical signals produced by the ear were collected by electrodes and fed into a digital oscilloscope and played back by a loud speaker.

Tissue engineers have previously had little success replicating the complicated three dimensional structure of the ear using biodegradable scaffolds. By using 3D printing the complex geometric structure of the ear can be built up layer by layer to exact specifications.

Integrating electronics into engineered tissues has also proved difficult in the past. McAlpine said: “There are mechanical and thermal challenges with interfacing electronic materials with biological material.

“Our work suggests a new approach – to build and grow the biology up with the electronics synergistically and in a 3D interwoven format.”

Previous approaches have seen 2D sheets of electronics attached to a surface of tissue.

In the future the team hope to incorporate other materials into the ear. These could include electronic sensors that detect pressure, which could enable the bionic ear to pick up acoustic sounds.