We hear sounds thanks to our eardrums; sound waves create varying amounts of pressure on the eardrum, and these vibrations are transmitted to the inner ear where nerves translate these vibrations to sensations that we perceive as sound. A microphone works in a similar manner, with a diaphragm transforming air vibrations into varying electrical currents that can then be processed and amplified as needed. What would it take to replace the human eardrum with a prosthetic device that could provide a sense of hearing?
That’s the question that researchers at the Suzhou Institute of Nanotech and Nanobionics (SINANO) in China decided to tackle. The problem is that most microphones use a rigid material for the diaphragm, which does not function well in the flexible environment of the human body. Instead, the scientists were able to construct a flexible electronic eardrum. They created a thin elastic membrane that is only 50 microns thick, which is thinner than a typical human hair. They incorporated nano-sensors that can detect the vibrations and convert them to electrical signals. The system has a suitable frequency response range of 20 Hz to 13 kHz, which compares favorably with the average human ear’s range of 20 Hz to 20 kHz.
This research could lead to the development of a bionic ear that could generate electrical signals that could then be interpreted directly by the brain. This could open a new avenue to hearing for those who have lost the ability through disease or traumatic injury.