3D printed ear could restore hearing

A 3D printed bionic ear that can 'hear' radio frequencies far beyond the range of normal human capability has been unveiled by scientists at Princeton University.

The finished ear consists of a coiled antenna inside a cartilage structure made up of 3D printed cells, nanoparticles and cell culture. Two wires lead from the base of the ear and wind around a helical cochlea – the part of the ear that senses sound – which can connect to electrodes. "In general, there are mechanical and thermal challenges with interfacing electronic materials with biological materials," said lead researcher Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton. "Previously, researchers have suggested some strategies to tailor the electronics so that this merger is less awkward. That typically happens between a 2D 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 3D interwoven format." The technique allowed the researchers to combine the antenna electronics with tissue within the highly complex topology of a human ear. An off-the-shelf 3D printer was used to combine a matrix of hydrogel and calf cells with silver nanoparticles to form an antenna. Although further work and extensive testing needs to be carried out before the technology can be used on a patient, the researchers believe the ear could be used to restore or enhance human hearing. They are now looking to incorporate other materials, such as pressure sensitive electronic sensors, to enable the ear to register acoustic sounds.