圆窗激振式人工中耳听力补偿力学机制及振子参数优化研究

Round window driving is a new type of hearing compensating method in implantable middle ear hearing device. It is one of the most potential techniques for mixed deafness treatment, as it can compensate hearing loss bypassing ossicular chain. However, as this hearing compensating method's mechanism is still unknown, we can not design hearing compensating signal processing algorithm accordingly. In addition,there still lack of design criterion on this compensating method's actuator,the actuator can not couple with the inner ear effectively, and its's clinical ultilization turn out great variability. Based on our study on human out and middle ear sound transmission mechanism, this project seeks to establish cochlear morphological and mechanical databases, and construct a whole human ear biomechanical model which can reflect the inner physicological characteristics of the cochlea by biomechanics, fluid mechanics, and structural dynamic principle. By simulating the dynamics behavior of the inner hair cell stereocillia, the hearing compensating mechanical mechanism of round window driving is investigated. Moreover, the mapping between the hearing loss level and the actuator's required inputs is analyzed. Furthermore, a human ear-acutator coupling mechanical model is established. By analyzing the influence of preload, support stiffness, couple face's material property et al. on the risidual hearing and hearing compensation, the optimization principle of actuator's key design parameters is investigated. A new type of piezoelectric actuator conform to round window physiological anatomy environment is designed and fabricated. The research results can lay a theoretical foundation to optimize, enhance and develop comprehensive performance of implantable middle ear hearing device's actuator, and provide a reliable solution to mixed deafness treatment.

圆窗激振是人工中耳发展的一个新方向，它避开听骨链直接补偿听力损伤，是治疗混合性聋最有潜力的技术之一。但其听力补偿机理尚不清楚，不能有效设计补偿算法；且缺乏振子设计准则，振子与植入环境耦合不理想，临床听力补偿效果不稳定。本项目拟在现有外、中耳研究基础上，构建耳蜗结构形态及生物力学特性数据库，综合运用生物力学、流体力学和结构动力学原理，建立能反映耳蜗内生理特征的整耳力学模型；通过分析圆窗激振下内毛细胞纤毛的力学行为特征，揭示圆窗听力补偿的力学机制，构建听力损伤级别与振子输入力、输入位移间映射关系；建立振子介入的人耳系统耦合力学模型，综合分析振子植入预载荷、支架刚度、及与圆窗连接界面材料特性等对残余听力和听力补偿性能的影响，确定振子关键设计参数的优化准则；在此基础上，研制出一套符合圆窗植入解剖环境的压电振子。成果将为人工中耳振子综合性能优化、提升及开发奠定理论基础，为混合性聋提供可靠解决方案。

圆窗激振是人工中耳发展的一个新方向，它避开听骨链直接补偿听力损伤，是治疗混合性聋最有潜力的技术之一。但其听力补偿机理尚不清楚，不能有效设计补偿算法；且缺乏振子设计准则，振子与植入环境耦合不理想，临床听力补偿效果不稳定。针对上述问题，本项目基于微CT扫描和扫描电镜成像等技术，构建了人耳几何结构数据库；采用有限单元法建立了耳蜗微观力学模型，对比分析了圆窗激振与正常感声下听毛细胞纤毛的动态响应，揭示以基底膜响应为评价准则将高估圆窗激振补偿效果，解释了其临床效果不及理论设计值的原因；建立了振子介入耦合人耳传声力学模型，系统分析了振子质量、支架刚度、植入预紧力等关键设计参数对听力补偿的影响，发现了振子质量越大高频效果越差、支架由筋膜提升至钛合金将提高振子全频段性能、植入预紧力存在有助于提高听力补偿高频效果、增加耦合层将增大大横截面积振子的听力补偿性能等结论；研究了三种典型中耳病变对圆窗激振性能影响，并发现了患者中耳病变是圆窗激振式人工中耳临床个体差异较大的主因之一；并基于上述结论，设计了一款具有自主知识产权的压电式人工中耳作动器；最终，实验验证了所提出的压电叠堆激振方案具有高频优越的性能。上述研究为人工中耳振子综合性能优化、提升及开发奠定理论基础，为混合性聋提供可靠解决方案。