Developing Hearing Devices

Scientists are using 3-D printing tools plus a cell culture to create what is termed a bionic ear. Scientists at Princeton University have created a functional ear that can hear radio frequencies far beyond the range of normal human capability. This project is the research team’s first effort to create a fully functional organ that not only replicates a human ability but extends it by using embedded electronics. It is also the first time that researchers have been able to demonstrate that 3-D printing is an effective strategy for interweaving tissue with electronics.

“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, at Princeton and the project’s lead researcher.

First, the researchers use a 3-D printer that instead of depositing ink, the printer puts down a polymer material and calf cells with silver nanoparticles to form an antenna. The finished ear has a coiled antenna inside a cartilage structure. Two wires lead from the base of the ear and wind around a helical cochlea which senses sound which is connected to electrodes.

According to the team, the ear in principle can be used to restore or enhance human hearing as electrical signals produced by the ear could be connected to a patient’s nerve endings similar to a hearing aid.

An article was published on the research online in “Nano Letters”. Support for this research was provided by Defense Advanced Research Projects Agency (DARPA), the Air Force Office of Scientific Research, NIH, and the Grand Challenges Program at Princeton University.

In another research project concerning the ear, Daniel Coelho M.D Co-Director of the Virginia Commonwealth Medical Center’s “Cochlear Implant Center is the first surgeon in central
Virginia to implant a new bone conduction hearing device that restores hearing.

According to Coelho, the device called the Sophono Alpha System uses implantable magnets that allow the patient to wear a small device that conducts sound to the patient’s inner ear, leading to significantly improved hearing. The technology helps individuals unable to wear traditional hearing aids, patients with chronic inflammation or infection of the ear canal, and children with aural atresia which is the absence or closure of an ear or ear canal.

“The device sends sound vibrations directly to the patient’s hearing ear, allowing the person to hear sound from all sides,” said Coelho. “By using magnets, this technology offers a potential alternative to other similar devices that work by using a metal attachment that goes through the skin to the skull.”

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