An increasing number of (those with severe and profound sensorineural hearing loss, SSHL / PSHL) have benefited from cochlear implants (CIs). The exterior components of CIs, including the speech processing system, exterior coil, power supply component, and microphone (sensor), can be attract attention and inconvenient, may embarrass patients, can limit patients’ social activities, can cause the inevitability of silent sleep (24/7 h) and complicate patients’ daily activities, for example, during bathing or while participating in swimming or other sports. To eliminate these disadvantages, totally implantable cochlear implants (TICIs) must be studied. The most essential challenge is the implantable microphone (sensor), which needs to be collect acoustic signals and convert them into electrical signals. Research on implantable microphones has made progress. The most representative designs are as follows: the TICA from Implex, Munich, Germany; two products, the TIKI and Carina, from Cochlear, Sydney, Australia; and the Esteem from Envoy, Saint Paul, MN, USA. The above designs have different advantages and disadvantages, and further research is ongoing. Beginning in early 2001, our team in the Department of Otology and Skull Base Surgery at the Eye, Ear, Nose and Throat Hospital of Fudan University has concentrated on researching miniature piezoelectric microphones for totally implantable middle ear systems. In 2004, we designed and built a piezoelectric microphone that can be connected to the head of the malleus of a cat in order to collect acoustic vibration signals.