The conversion of sound vibration into electrical potential is a critical function performed by cochlear hair cells. Unlike the regenerative capacity found in various other cells throughout the body, cochlear sensory cells lack the ability to regenerate once damaged. Furthermore, a decline in the quantity of these cells results in a deterioration of auditory function. Piezoelectric materials can generate electric charge in response to sound wave vibration, making them theoretically suitable for replacing hair cell function. This study explores an innovative approach using piezoelectric nanocomposite filaments, namely poly(vinylidene fluoride), poly(vinylidene fluoride)/barium titanate, and poly(vinylidene fluoride)/reduced graphene oxide, as self-powered acoustic sensors designed to function in place of cochlear hair cells. These flexible filaments demonstrate a unique ability to generate electricity in response to frequency sounds from 50 up to 1000 Hz at moderate sound pressure levels (60–95 dB), approaching the audible range with an overall acoustoelectric energy conversion efficiency of 3.25%. Serving as self-powered acoustic sensors, these flexible filaments hold promise for potential applications in cochlear implants, with a high sensitivity of 117.5 mV (Pa·cm²)⁻¹. The cytocompatibility of these filaments was assessed through in vitro viability tests conducted on three cell lines, serving as a model for inner ear cells.

Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes, becoming sometimes life threatening for the patients. Therefore, aggressive antibiotic therapies are administered, which often require the use of last-resort drugs, if the infection is caused by multi-drug-resistant bacteria. Reducing the risk of bacterial contamination of medical devices in the hospitals has thus become an emerging issue. Promising routes to control these infections are based on materials provided with intrinsic bactericidal properties (i.e., chemical action) and on the design of surface coatings able to limit bacteria adhesion and fouling phenomena (i.e., physical action), thus preventing bacterial biofilm formation. Here, we report the development and validation of coatings made of layer-by-layer deposition of electrospun poly(vinylidene fluoride-co-trifluoro ethylene) P(VDF-TrFE) fibers with controlled orientations, which ultimately gave rise to antifouling surfaces. The obtained 10-layer surface morphology with 90° orientation fibers was able to efficiently prevent the adhesion of bacteria, by establishing a superhydrophobic-like behavior compatible with the Cassie-Baxter regimen. Moreover, the results highlighted that surface wettability and bacteria adhesion could be controlled using fibers with diameter comparable to bacteria size (i.e., achievable via electrospinning process), by tuning the intra-fiber spacing, with relevant implications in the future design of biomedical surface coatings.