In order to develop a capacitive solid state sensor that makes use of an electret, a theoretical analysts 1s given of an electret air-gap held-effect structure This structure 1s basically an MOS transistor with a movable gate and can thus be considered as a pressure-sensltlve field effect transistor It 1s shown that the addition of a metal layer on top of the semlconductor-oxide increases the s...

The last few years have seen the start of a unique change in microphones for consumer devices such as smartphones or tablets. Almost all analogue capacitive microphones are being replaced by digital silicon microphones or MEMS microphones. MEMS microphones perform differently to conventional analogue microphones. Their greatest disadvantage is significantly increased self-noise or decreased SNR...

This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, battery-less SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their u...

This paper deals with a frontend part of the readout circuit developed as an integrated circuit that after bonding together with a MEMS capacitive microphone (MCM) chip will be used in a noise dosimeter applicable in very noisy and harsh environment, e.g. mine. Therefore, the main attention has been paid to the high dynamic range, low offset and low noise of the developed readout interface as w...

Broadband acoustic sensing, over several decades of frequency, has traditionally been difficult to achieve. An alternative approach to conventional condenser microphones is to use capacitive micromachined ultrasonic transducer (CMUT) membranes with a sensitive radio frequency (RF) detection method. Since the resonant frequency of a typical CMUT membrane is several megahertz, the membrane respon...

2014 A method using a capacitive microphone as an ionization chamber enables the ionizing collision of a fast particle with a gas atom to be observed. The probability of this collision and the corresponding number of electrons removed were measured in air, for 4 MeV alpha particles leaving a radioactive source. Tome 39 N° 15 ler AOL1T 1978 LE JOURNAL DE PHYSIQUE LETTRES Classification Physics A...

We report the realization of an acoustic capacitive microphone formed by graphene/poly(methyl methacrylate) (PMMA). It is first time that ultra-large graphene/PMMA membrane suspended fully over cavity has been fabricated releasing silicon dioxide sacrificial layer underneath membrane. The novelty in fabrication method etched hydrogen fluoride vapor from back partly substrate. Using new process,...