AUTHOR=Danti Serena , Berrettini Stefano TITLE=New perspectives for piezoelectric material-based cochlear implants: getting to nano JOURNAL=Frontiers in Materials VOLUME=11 YEAR=2024 URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2024.1362141 DOI=10.3389/fmats.2024.1362141 ISSN=2296-8016 ABSTRACT=

Sensorineural hearing loss (SNHL) occurs when the sound transduction mechanism in the inner ear is compromised, because of impairments affecting the sensory hair cells—the actual biological transducers (90% of cases)—or the neurons. SNHL results in a broad spectrum of developmental, cognitive and psycho-social damages. To date, only cochlear implants (CIs) can offer a therapeutic solution to patients. They are multi-component electronic devices, surgically implanted, which capture, elaborate and convert the sound into electric stimuli delivered to the cochlea. Due to inherent limitations of the current electronic-based CIs, a new class of devices has been envisioned, which is based on piezoelectric materials. However, using piezoelectric membranes, the obtained sensitivity was not enough. The new frontiers for piezoelectric material-based CI aim at synergizing micro/nanofabrication aided by multiscale materials modeling with an in vivo tissue engineering approach to provide an implantable biomaterial-based system for SNHL, acting as a next-generation CI. Specifically, the envisioned device will move forward the primitive concept of bulk-structured piezoelectric CIs by designing a nanostructured material (e.g., based on nanofibers) to be precisely delivered and be intimately and efficiently integrated with the cochlear microenvironment. Piezoelectric material-based CIs are indeed hypothesized to have a much higher resolution of electrical stimulation with more than hundreds of channels, compared to maximum 22 stimulating elements present in electronic-based CIs. Moreover, the stimulation site will be closest to peripheral nerve fiber endings for maximal resolution. This would be the first sensory implant with a feedback mechanism on a micrometer scale.