An AlN MEMS Piezoelectric Microphone for Aeroacoustic Applications

High-sensitivity accelerometer composed of ultra-long vertically aligned barium titanate nanowire arrays

“…Mechanical vibration was provided by a miniature electromagnetic shaker (Labworks, Inc., ET-132) and the voltage measurements from the sensor under vibration excitation was performed using a voltage follower/ buffer amplifier with unity gain from Linear Technologies (LTC6240CS8), which was chosen for its high input resistance (1TO), low bias current (0.2 pA) and low noise (voltage noise o10nV/OHz) utilized by Williams et al 40,41 for AlN piezoelectric microphones. The sensor and voltage follower was placed inside a grounded faraday cage that acts as a noise shield from electromagnetic interference to improve the signal-to-noise ratio of the sensor.…”

Stress controlled pulsed direct current co-sputtered Al1−xScxN as piezoelectric phase for micromechanical sensor applications

“…Because of its superior voltage response and low dielectric loss, 1 the non-toxic III-V semiconductor aluminum nitride is a preferred piezoelectric material for micro-electro-mechanical system (MEMS) sensor applications. 2 AlN MEMS sensor devices can facilitate the detection of a multitude of phenomena from basic acceleration 3 over sound waves 4 to magnetic fields 5 with high accuracy. Commonly realized by thinning the substrate in their sensitive area in order to maximize the strain mediated to the piezoelectric film, MEMS sensors stringently require to control residual stress introduced by this layer.…”

Towards a sub 15-dBA optical micromachined microphone

“…3,4 These microphones have been used to address high dynamic-range applications including aero-acoustic measurements. The lowest noise demonstrations of silicon microphones have utilized capacitive-based detection.…”

“…8,[14][15][16] Figure 1 presents a schematic of a bottom-inlet microphone, with the lumped-parameter acoustical-mechanical network superimposed onto the device schematic. Such models are commonly used to study the microphone's dynamic response to sound pressure 3 as well as the microphone's thermal-mechanical noise spectrum resulting from various dissipative elements within the package. 15 The inspiration to directly show the network superimposed onto the device is from F€ uldner et al, 14 and the overall structure of the model presented in Fig.…”

“…20 and 21]. Assuming 4.4-mm 3 volume and an acoustical vent-resistance chosen to realize a 20-Hz corner, the input-pressure-referred vent-noise spectrum is presented in Fig. 2(a).…”