Kang Hou-Yong, Na Gao, Chi Fang-Lu, Jin Kai, Pan Tie-Zheng, Gao Zhen
Department of Otorhinolaryngology, Head & Neck Surgery, the First Affiliated Hospital, Chongqing Medical University, Chongqing, PR China, 400016.
Biomed Eng Online. 2012 Feb 22;11:10. doi: 10.1186/1475-925X-11-10.
Many microphones have been developed to meet with the implantable requirement of totally implantable cochlear implant (TICI). However, a biocompatible one without destroying the intactness of the ossicular chain still remains under investigation. Such an implantable floating piezoelectric microphone (FPM) has been manufactured and shows an efficient electroacoustic performance in vitro test at our lab. We examined whether it pick up sensitively from the intact ossicular chain and postulated whether it be an optimal implantable one.
Animal controlled experiment: five adult cats (eight ears) were sacrificed as the model to test the electroacoustic performance of the FPM. Three groups were studied: (1) the experiment group (on malleus): the FPM glued onto the handle of the malleus of the intact ossicular chains; (2) negative control group (in vivo): the FPM only hung into the tympanic cavity; (3) positive control group (Hy-M30): a HiFi commercial microphone placed close to the site of the experiment ear. The testing speaker played pure tones orderly ranged from 0.25 to 8.0 kHz. The FPM inside the ear and the HiFi microphone simultaneously picked up acoustic vibration which recorded as .wav files to analyze.
The FPM transformed acoustic vibration sensitively and flatly as did the in vitro test across the frequencies above 2.0 kHz, whereas inefficiently below 1.0 kHz for its overloading mass. Although the HiFi microphone presented more efficiently than the FPM did, there was no significant difference at 3.0 kHz and 8.0 kHz.
It is feasible to develop such an implantable FPM for future TICIs and TIHAs system on condition that the improvement of Micro Electromechanical System and piezoelectric ceramic material technology would be applied to reduce its weight and minimize its size.
为满足全植入式人工耳蜗（TICI）的植入要求，已研发出多种麦克风。然而，一种不破坏听骨链完整性的生物相容性麦克风仍在研究中。我们实验室已制造出这种可植入式浮动压电麦克风（FPM），并在体外测试中显示出高效的电声性能。我们研究了它是否能从完整的听骨链中灵敏地拾取声音，并推测它是否是一种理想的可植入式麦克风。
动物对照实验：处死5只成年猫（8只耳朵）作为模型，以测试FPM的电声性能。研究分为三组：（1）实验组（附着于锤骨）：FPM粘贴在完整听骨链的锤骨柄上；（2）阴性对照组（体内）：FPM仅悬挂在鼓室内；（3）阳性对照组（Hy-M30）：一个高保真商用麦克风放置在实验耳部位附近。测试扬声器依次发出频率范围为0.25至8.0 kHz的纯音。耳内的FPM和高保真麦克风同时拾取声振动，并记录为.wav文件进行分析。
在2.0 kHz以上的频率范围内，FPM能像体外测试一样灵敏且平稳地转换声振动，而在1.0 kHz以下，由于过载质量，转换效率较低。尽管高保真麦克风的表现比FPM更高效，但在3.0 kHz和8.0 kHz时两者无显著差异。
如果应用微机电系统和压电陶瓷材料技术的改进来减轻其重量并最小化其尺寸，那么为未来的TICI和TIHA系统开发这种可植入式FPM是可行的。
