Electrical Model and Analysis of Vibration Characteristic of Differential Floating Mass Transducer for Fully-Implantable Middle Ear Hearing Devices

A differential floating mass transducer (DFMT), with high vibration efficiency and simple attachment for implant, has been developed in Korea for fully implantable middle ear hearing devices (F-IMEHDs). The vibration equation and the mechanical model of the DFMT have been defined to analyze the vibration characteristic of the DFMT. In this paper, the mechanical model is transformed to the electrical model by the equivalent relationship between each other because the electrical model enables the simple analysis of the DFMT vibration characteristics using a computer program such as PSpice. Then, the electrical model has been simulated through the PSpice program as change the values of the passive elements in the electrical model. The simulation results showed that the resonant frequency and the vibration displacement characteristics of the simulated DFMT depend on the capacitance in the electrical model. After experiment for measuring vibration displacement of the implemented DFMT has been performed, the measured vibration characteristic has been compared with the simulated result using the selected values of the passive elements to generate proper displacement at the resonant frequency and flat region in the frequency response. The compared results showed that the vibration characteristic of the DFMT through the electrical model is similar to the measured vibration characteristics of the implemented DFMT. Through the comparison, it is verified that the electrical model of the DFMT is useful to analyze the vibration characteristic of the DFMT without solving the vibration equation extracted from the mechanical model.