Nano Lett. (2013)

By combining biological tissue with functional electronics, bionic body parts can be created that could potentially offer superior capabilities to their natural counterparts. Tissue and electronics have previously been coupled by using planar electronic devices that can conform to the surface of natural tissue and such devices have, for example, been used to map brain activity. Michael McAlpine and colleagues at Princeton University and John Hopkins University have now merged the two concepts by using a 3D printer to build a bionic ear.

The researchers first created a computer-aided design (CAD) drawing of an ear that had an integrated circular coil antenna connected to cochlea-shaped electrodes. An alginate hydrogel matrix seeded with chondrocyte cells was used to make the shape of the ear, and a conducting polymer infused with silver nanoparticles was used to make the antenna and the electrodes. The materials are fed into the 3D printer, which uses slices of the CAD model to build the structure layer-by-layer. The cells in the hydrogel matrix can then be used to grow cartilage tissue in the shape of the hydrogel scaffold by immersing the printed ear in chondrocyte culture media.

The resulting bionic ears can sense electromagnetic signals in the radio frequency range, and a pair of ears can listen to stereo audio music.