Development of PZT Thin-Film Microactuators for Intracochlear Applications

背景：听力损失是老年人和长时间在嘈杂环境中工作的人群中常见的残疾。大多数听力损失的人有感觉神经损伤，由于耳蜗毛细胞功能障碍或损失。对于轻度至中度听力损失，传统的助听器可以放大传递到耳朵的声音。对于更严重的听力损失，人工耳蜗可以通过耳蜗中的电极直接电刺激听觉神经元。在这两个极端之间，有一群患者失去了相当多的高频听力，但保留了一些低频听力。这些患者中的许多人使用助听器效果很差，但不适合人工耳蜗植入。最近，有证据表明，对于这一不断增长的患者群体，最有效的康复类型是在同一只耳朵中结合电和声刺激（CEAS）。CEAS策略同时使用声放大（助听器）和电刺激（人工耳蜗）。结果表明，患者在嘈杂环境下有较好的单词识别能力。为了在单个设备中实现CEAS，可以将刺激电极和声学致动器集成并放置在耳蜗内。虽然耳蜗内电极研究得很好，但耳蜗内声学致动器是新颖的，尚未被探索。目的：研制用于耳蜗内的铅锆钛氧化物（PZT）薄膜声学微致动器。有两个具体的目标要实现。第一个目标是设计和制造一个微致动器探头，其尖端有一个PZT薄膜压电隔膜作为声致动器。该驱动器旨在提供200纳米位移，带宽从15 Hz到3 kHz，尺寸小于0.8 mm x 0.8 mm。探针的尖端用生物相容性材料密封，然后植入耳蜗。第二个目标是进行急性动物实验，通过测量豚鼠的听觉脑干反应来证明所提出的微致动器探针的可行性。智力价值：所提议的研究具有充分的智力价值。首先，本研究具有变革性。这项研究的结果将使一种新型的人工耳蜗植入物成为可能，这种植入物将电和声刺激集成在一个单一的装置中。这将为目前的人工耳蜗技术开辟一个全新的发展方向。其次，拟议的研究极大地拓宽了该领域的知识。例如，拟议的研究有一个精心策划的动物实验来验证我们的假设并证明可行性。这将是第一个关于耳蜗内声学驱动器的动物研究。第三，本研究具有转译性。以PZT薄膜技术为核心的研究形成了一种新的研究范式。它补充了传统的微机电系统（MEMS）技术，后者无法满足耳蜗内应用所遇到的挑战。PZT薄膜技术还可以实现广泛的应用，例如扫描内窥镜，用于DNA操作的纳米定位器和用于生物流体的粘度计。更广泛的影响：目前，估计有2.78亿人患有听力残疾。这些听力障碍患者的良好人群可以潜在地受益于拟议的耳蜗内驱动器。听力康复研究将变得越来越重要，因为美国人口正在老龄化，预期寿命正在增加。拟议的研究还将通过开发关于PZT薄膜微器件的新课程，招募代表性不足的本科生和本科生，通过专利和许可进行技术转让，工业和国际合作，推广和继续教育来扩大其影响。

PI: ShenProposal: 1159623Background: Hearing loss is a common disability in aging seniors and people who work long hours in noisy environments. The majority of persons with hearing loss have sensorineural impairments, due to dysfunction or loss of cochlear hair cells. For mild to moderate hearing loss, conventional hearing aids amplify sounds delivered to the ear. For more severe hearing loss, cochlear implants can directly stimulate auditory neurons electrically via an electrode in the cochlea. Between these two extremes, there is a group of patients who have lost considerable high-frequency hearing but have some preserved low-frequency hearing. Many of these patients do poorly with hearing aids but are not candidates for cochlear implants. Recently, there is evidence that the most effective type of rehabilitation for this growing group of patients is to combine electrical and acoustic stimulation (CEAS) in the same ear. The CEAS strategy uses acoustic amplification (hearing aid) and electrical stimulation (cochlear implant) simultaneously. Results show that patients have better word recognition under noisy environments. To enable CEAS in a single device, stimulating electrodes and acoustic actuators could potentially be integrated and placed inside cochlea. While Intra-cochlear electrodes are well studied, intra-cochlear acoustic actuators are novel and have not been explored.Objectives & Goals: The proposed research is to develop Lead-Zirconium-Titanium Oxide (PZT) thin-film acoustic micro-actuators for intra-cochlear use. There are two specific goals to achieve. The first goal is to design and fabricate a micro-actuator probe, whose tip has a PZT thin-film piezoelectric diaphragm serving as an acoustic actuator. The actuator aims to deliver 200-nm displacement for a bandwidth from 15 Hz to 3 kHz with a size less than 0.8 mm x 0.8 mm. The tip of the probe, sealed with a biocompatible material, is then implanted into the cochlea. The second goal is to conduct acute animal tests to demonstrate the feasibility of the proposed micro-actuator probe by measuring auditory brainstem responses in guinea pigs.Intellectual Merits: The proposed research has ample intellectual merits. First, the proposed research is transformational. Results of this research will enable a new class of cochlear implants that integrate electric and acoustic stimulation in a single device. It will open a completely new direction for the current cochlear implant technologies. Second, the proposed research tremendously broadens the knowledge of the field. For example, the proposed research has a well-planned animal study to test our hypothesis and demonstrate the feasibility. This will be the first animal study on intra-cochlear acoustic actuators. Third, this research is translational. The PZT thin-film technology at the core of the proposed research forms a new research paradigm. It complements traditional technology of micro-electric-mechanical-systems (MEMS), which are not able to meet the challenges encountered in intra-cochlear applications. The PZT thin-film technologies can also enable a wide range of applications, such as scanning endoscopes, nano-positioners for DNA manipulation, and viscosimeters for biofluids.Broader Impacts: Currently, it is estimated that 278 million people have hearing disability. A good population of these hearing-disabled patients can potentially benefit from the proposed intra-cochlear actuators. Hearing rehabilitation research will become progressively important, because US population is aging and life expectancy is increasing. The proposed research will also broaden its impact via development of new curriculum on PZT thin-film microdevices, recruitment of underrepresented and undergraduate students, technology transfer via patents and licensing, industrial and international collaboration, outreach, and continuing education.