Combined electric and acoustic stimulation has proven to be an effective strategy to improve hearing in some cochlear implant users. We describe an acoustic microactuator to directly deliver stimuli to the perilymph in the scala tympani. The 800 µm by 800 µm actuator has a silicon diaphragm driven by a piezoelectric thin film (e.g., lead-zirconium-titanium oxide or PZT). This device could also be used as a component of a bimodal acoustic-electric electrode array. In the current study, we established a guinea pig model to test the actuator for its ability to deliver auditory signals to the cochlea in vivo. The actuator was placed through the round window of the cochlea. Auditory brainstem response (ABR) thresholds, peak latencies, and amplitude growth were calculated for an ear canal speaker versus the intracochlear actuator for tone burst stimuli at 4, 8, 16, and 24 kHz. An ABR was obtained after removal of the probe to assess loss of hearing related to the procedure. In some animals, the temporal bone was harvested for histologic analysis of cochlear damage. We show that the device is capable of stimulating ABRs in vivo with latencies and growth functions comparable to stimulation in the ear canal. Further experiments will be necessary to evaluate the efficiency and safety of this modality in long-term auditory stimulation and its ability to be integrated with conventional cochlear implant arrays.
A preliminary model of an intracochlear piezoelectric microphone is proposed that mimics the structure of stereocilia in the cochlea. Its purpose is to determine the crucial system parameters prior to fabrication of an actual testing set up via a mathematical model. As a first approximation, the system is modeled as a 1-D, periodic beam with N identical substructures. Each one consists of a nanorod grown on an Si substrate, a bottom electrode, piezoelectric thin film, and two top electrodes. The model consists of: a finite element analysis of a single substructure to obtain its flexibility matrix and differential voltage (DV) under unit loads; and a mapping of these results through the structure to predict displacement and DV of each substructure. A parametric study is then conducted based on this model. It was determined that the nanorod length was the most critical parameter in improving sensitivity. By increasing the amount of drag force on the nanorods the sensitivity grows. Substructures near fixed boundaries generate higher DV thus leading to better sensitivity too. The number of substructure in the microphone would also affect signal-to-noise ratio.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.