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Feasibility of Totally Implantable ABM System Using Artificial Basilar Membrane
- Subtitle
- a Conceptual Design
- Author(s)
- 정주용
- Advisor
- 정연훈, 오승하
- Department
- 일반대학원 의학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2020-08
- Language
- eng
- Alternative Abstract
- Introduction: Cochlear implants (CIs) have become the standard treatment for patients who suffer from sensorineural hearing loss due to damage or loss of hair cells in the cochlea. However, conventional CIs have some challenges, such as problems caused by the use of extracorporeal devices, and have a very high power consumption for frequency analysis measurements. To overcome these challenges, a fully implantable CI (FICI) was developed. Even the newly developed FICI has some limitations, such as too much ambient noise produced from a subcutaneous microphone and a battery that requires frequent recharging. To solve these two problems, artificial basilar membranes (ABMs) made of piezoelectric materials have been studied. This study aimed to verify the conceptual idea of a totally implantable ABM system. Methods: Using the ABM we developed in a previous study, we constructed an electronic module (EM) for the amplification of electrical output from our ABM and investigated the auditory brainstem responses of deafened guinea pigs that were stimulated by the amplified output of electricity generated by the ABM in combination with the EM in response to an actuator. Further, we implemented an optimal method for coupling ABMs to the middle ear ossicle and explored the possibility of a bioelectronic middle ear microphone. Results: The ABM sensitivity as a sensor was 1.82 mV/µm. When calculated by replacing with sound pressure, the ABM sensitivity was 0.120 mV/Pa in this study. In the ABM plus EM in vivo test, the signal, which was generated from the ABM and amplified by the EM, was able to induce auditory brainstem responses (ABRs) in deafened guinea pigs, indicating its capacity to mimic basilar membrane functions. The threshold of ABR was the actuator's stimulus voltage of 6V. As the intensity of the stimulus increased from 6 V to 10 V, the tracing waveform showed a larger amplitude and shorter latency. In the tube-type connector coupled to the umbo, we measured 120 µV of electrical output from the ABM, which was stimulated by sound (110 dB SPL, 750 Hz). Frequency characteristics showed that ABM with the tube-type connector coupled to the umbo is reduced to three channels compared to six channels in the ABM in response to actuator stimulation. The power of the whole ABM system was 100 times lesser than that of conventional CIs. In the case of the ABM system with umbo connection, the electrical output was 10 times lesser than that of the ABM system without coupling. Conclusion: We developed a prototype of the totally implantable ABM system, consisting of the ABM, EM, and electrode, and assessed its feasibility. We obtained meaningful auditory brainstem responses by implanting it into guinea pigs. The power of the entire ABM system was 100 times lesser than that of conventional CIs. In the case of the ABM system with umbo connection, the electrical output was 10 times lesser than that of the ABM system without coupling. Although at the time there was insufficient electrical power to operate the entire system, we found a possibility of a self-powered ABM system, which might be one of the future options for a completely implantable device. Improving the efficiency of the ABM and developing an efficient ossicular connection (coupling) technology are challenges that need to be studied further.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Medicine > 4. Theses(Ph.D)
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