Scientists 'print' 3D bionic ear

Scientists, including an Indian-origin researcher, have created a 3D-printed 'bionic' ear that can "hear" radio frequencies far beyond the range of normal human capability.

Using off-the-shelf printing tools, the scientists at Princeton University explored 3D printing of cells and nanoparticles followed by cell culture to combine a small coil antenna with cartilage, creating a 'bionic' ear.

"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.

"Our work suggests a new approach - to build and grow the biology up with the electronics synergistically and in a 3D interwoven format," said McAlpine.

Last year, a research effort led by McAlpine and Naveen Verma, an assistant professor of electrical engineering, and Fio Omenetto of Tufts University, resulted in the development of a "tattoo" made up of a biological sensor and antenna that can be affixed to the surface of a tooth.

This project, however, is the team's first effort to create a fully functional organ: one that not only replicates a human ability, but extends it using embedded electronics.

"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 researchers wrote in the article in the journal Nano Letters.

"This field has the potential to generate customised replacement parts for the human body, or even create organs containing capabilities beyond what human biology ordinarily provides," said the researchers.

Ear reconstruction "remains one of the most difficult problems in the field of plastic and reconstructive surgery," they wrote.

The team turned to a manufacturing approach called 3D printing. These printers use computer-assisted design to conceive of objects as arrays of thin slices.

The printer then deposits layers of a variety of materials - ranging from plastic to cells - to build up a finished product.

This is the first time that researchers have demonstrated that 3D printing is a convenient strategy to interweave tissue with electronics.

The technique allowed the researchers to combine the antenna electronics with tissue within the highly complex topology of a human ear.

The researchers used an ordinary 3D printer to combine a matrix of hydrogel and calf cells with silver nanoparticles that form an antenna. The calf cells later develop into cartilage.