MEMS design and modelling based on resonant gate transistor for cochlear biomimetical application

Abstract

The electromechanical behaviour and frequency response of the human cochlear have been described to be mimicked using an array of resonant gate transistors (RGT). Presented in this paper are the mathematical model, geometrical analysis and novel design of RGT, employed for the physical model development of the cochlea. In an array of RGTs, the aluminium bridge gate structures with length of 0.57 mm-1.62 mm transduce the sound input signal into mechanical vibrations at audible frequency range of 1 kHz-8 kHz. The channels underneath the bridge gates transduce the mechanical vibrations into small signal drain currents with reasonable estimated sensitivity of 4 nA/Pa-17 nA/Pa. The gain amplification and resonant frequency reduction of RGT with respect to the voltage applied onto the bridge gate structure highlight the adaptive characteristics of a human cochlear. The proposed modelling approach can aid the fabrication design of RGT for cochlear model.

Mechanical Energy Sensing and Harvesting in Micromachined Polymer-Based Piezoelectric Transducers for Fully Implanted Hearing Systems: A Review

“…where γ is 1.875 for fundamental mode vibration, E is the Young's modulus, t represents thickness, w is the width, l is the length, I is the moment of inertia and ρ is the material's density [77]. At resonant frequency, the cantilever will vibrate at a maximum amplitude.…”

“…In the basilar membrane, the apex mainly responds at low frequency sound whereas the base is sensitive to high frequency sound signals, due to the varying rigidity along the membrane ( Figure 14 ). The BM is in the shape of a trapezoid where the base close to oval window is thick with short breadth giving high rigidity whereas the apex is thin and long breadth giving high flexibility [ 77 ]. In the current commercialised cochlear devices, the sensed signals by microphones are filtered by the digital signal processor technology that divides speech into different frequency bands, attaining the tonotopic distribution of frequency.…”

“…The geometrical dimension, shape and composition of the transducer influence the working frequency and bandwidth. For a simple cantilever, the mechanical resonant frequency is given by: where is 1.875 for fundamental mode vibration, is the Young’s modulus, represents thickness, is the width, is the length, is the moment of inertia and is the material’s density [ 77 ]. At resonant frequency, the cantilever will vibrate at a maximum amplitude.…”

“… The schematic illustration of an uncoiled basilar membrane demonstrating the tonotopic organisation behaviour along the membrane length [ 77 ]. Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer Nature MICROSYSTEM TECHNOLOGIES MEMS design and modelling based on resonant gate transistor for cochlear biomimetical application, R. Latif et al, COPYRIGHT (2016).…”

Characterization of embedded membrane in corrugated silicon microphones for high-frequency resonance applications

“…Microelectromechanical systems (MEMSs) microphones have been developed massively using the conventional complementary metal-oxide semiconductor (CMOS) process and have attracted explosive interest because of their advantages in terms of low production costs, long-term stability and device miniaturization (Huang et al , 2011). With their tiny size of few millimeters, MEMS microphones have been commercialized by several powerhouses of silicon (Si) microfabrication companies, such as Infineon, ST and Knowles, mainly for sound detection purposes, by integrating it into various kinds of electronic devices, such as mobile phones (Peña-García et al , 2018), computers, artificial ears (Latif et al , 2017), loudspeakers (Sugandi and Majlis, 2011), hearing aids (Woo et al , 2017) and handheld devices (Dehé et al , 2013). Among several types of microphones, the capacitive-type MEMS microphone will be the main focus in this study because it is considered to be one of the highest quality microphones and has been widely integrated using the CMOS fabrication (Buyong et al , 2011; Lo et al , 2017).…”