Leysieffer H, Baumann J W, Müller G, Zenner H P
Universitätsklinik für Hals-Nasen-Ohrenheilkunde, Tübingen.
HNO. 1997 Oct;45(10):801-15. doi: 10.1007/s001060050159.
A miniature, hermetically sealed implant was development and manufactured in several clinical and technical iteration steps based on the prototype of an implantable piezo-electric hearing-aid transducer described in Part 1 of the work presented here. The transducer is made of pure titanium (medical grade 2, ASTM F67) and designed to be implanted into the mastoid cavity. Transfer of mechanical oscillations to an ossicle in the middle ear is effected by a fixed directly coupling rod of pure titanium or via suitable coupling elements. The transducer is highly tuned with a resonance frequency in the range of 7-10 kHz, depending on the dynamic mass load. Below this resonance and down to low frequencies, the frequency response of elongation is smooth with a very small ripple of less than +/- 1 dB. Unlike the prototype, an increase in vibration amplitude of around 10 dB was achieved for a comparable power consumption. Vibration amplitude at low and middle frequencies is about 60 nm with a transducer voltage of 1 V, corresponding to an equivalent sound-pressure level of around 100 dB SPL at up to 1 kHz. At higher frequencies of up to 10 kHz, the output level increases to beyond 130 dB SPL. Nonlinear distortions at maximum volume (1 V) are extremely small (THD < 0.1%) throughout the whole transfer range. Due to an extremely short attack time (50 microseconds) and short release time (approximately 2 ms), the dynamic properties of the transducer allow good transmission of audio signals with fast changes in the time domain, i.e., plosives in speech signals. Electric power consumption at full volume and broadband signals is in the region of 1 microW. Unlike electromagnetic transducers described in the literature, the low power consumption of this piezoelectric transducer allows the realization of fully implantable hearing aids for rehabilitation of moderate to severe sensorineural hearing loss.
基于本文第一部分所述的植入式压电助听器换能器原型，经过几个临床和技术迭代步骤，研发并制造出了一种微型、气密密封的植入物。该换能器由纯钛（医用2级，ASTM F67）制成，设计用于植入乳突腔。机械振动通过纯钛制成的固定直接耦合杆或通过合适的耦合元件传递到中耳的听小骨。换能器经过高度调谐，共振频率在7 - 10 kHz范围内，具体取决于动态质量负载。在该共振频率以下直至低频，伸长频率响应平滑，纹波非常小，小于±1 dB。与原型不同的是，在相当的功耗下，振动幅度增加了约10 dB。在1 V的换能器电压下，低频和中频的振动幅度约为60 nm，对应于高达1 kHz时约100 dB SPL的等效声压级。在高达10 kHz的较高频率下，输出电平增加到超过130 dB SPL。在整个传输范围内，最大音量（1 V）时的非线性失真极小（THD < 0.1%）。由于极短的启动时间（50微秒）和短释放时间（约2毫秒），换能器的动态特性允许在时域中快速变化的音频信号（即语音信号中的爆破音）得到良好传输。全音量和宽带信号时的电力消耗在1微瓦左右。与文献中描述的电磁换能器不同，这种压电换能器的低功耗使得为中重度感音神经性听力损失康复而设计的完全植入式助听器得以实现。
