The World Health Organization describes deafness as the inability to hear sounds of 20dB or more in both ears. At present, 430 million people in the world have hearing loss and require some sort of intervention to improve their hearing. The WHO projects that by 2050, 2.5 billion will have some amount of hearing loss with about 28% of that value needing rehabilitation.
Deafness could present from birth–caused by bad genes–or infection when the baby was still in the womb, or other fetal diseases or disorders. It could be acquired over the years via ear infection, trauma to the ear, loud sound, exposure to chemicals that can damage hearing, nutritional deficiencies, chronic illnesses, old age, smoking, etc.
The common pathway of most the causes is the damage of the cochlea, which are specialized tiny hairs in the ear that transform sound to electrical energy which are sent to the brain for interpretation. Damage to this delicate structure is irreversible.
As expected, one of the treatment modalities for hearing loss is using an artificial cochlea and implants powered by an external source. Recent technology advances are on the verge of introducing an artificial cochlea that works without batteries and converts sound to an electrical signal
Piezo-tribo electric material
The treatment of hearing loss, nowadays, is largely by implants and cochlear implants powered from external sources. This model has its downsides like the need to recharge the battery frequently and they also cannot precisely amplify sound so that it’s understood by the listener.
That said, there is a need for improvement or perhaps use safer alternatives. One way of solving addressing this issue is by employing the use of a piezoelectric transducer. A piezoelectric transducer is an implantable hearing device that stimulates the chain of small ear bones as the piezoelectric stack expands and contracts. This in turn can stimulate the healthy cochlea hair cells which bring about hearing.
This device powers itself through pressure from compression from sound waves.
Another solution is the triboelectric materials that when moved by sound waves produce friction and static electricity. The difficulty in fabricating them and their inability to generate adequate signals across different frequencies are some of the most important downsides of this device that limits its efficacy.
This dilemma prompted Yunming Wang and his colleagues to create a hybrid that had both properties of piezoelectric and triboelectric transducer. Simply put, they designed a device that was easy to fabricate and used both compression and friction for stimulation of the cochlea. This synergy boosted the efficiency and sensitivity across a wide range of frequencies.
The researchers designed this new hybrid model piezo-triboelectric material, by coating barium titanate nanoparticles with silicon dioxide into a conductive polymer. Next, they dried this mixture’s flexible film after which they removed this coating using an alkaline solution. The result after the uncoating was spongy membranes with nanoparticles surrounded by spaces, this arrangement allowed the nanoparticles to bump into each other when they hit sound waves.
According to research, this instrument increased the membrane’s electrical output by 55% and is sensitive to a broad range of sound and voice.
This upgrade of hearing aids is a major advancement. This will improve the success rate of rehabilitation for people with hearing loss. The device has also lifted the burden of using transducers that require batteries as well as regular charges.
The hybrid device represents our greatest chance of treating hearing loss. It is economical and has eliminated the stress of buying batteries.