Low-Pressure Wafer-Level-Packaged Capacitive Accelerometers With High Dynamic Range and Wide Bandwidth Using Nano-Gap Sloped Electrode Design

Jeong, Yaesuk; Serrano, Diego; Ayazi, Farrokh

doi:10.1109/jmems.2017.2744260

Cited by 20 publications

(7 citation statements)

References 24 publications

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“…In an accelerometer, the total noise equivalent acceleration (TNEA) consists of the RMS sum of its mechanical noise (MNEA) and its interface circuit noise (CNEA), expressed in equations ( 1) and (2), respectively [11,14], where k B is the Boltzmann constant, T is the temperature, D is the damping coefficient, M is the moving mass, ∆C min is the capacitive resolution of the readout circuit, K is the stiffness, ε 0 is the permittivity, and A and d are the sense electrode area and gap size, respectively.…”

Section: Design Methodologymentioning

confidence: 99%

“…So far, we have demonstrated different capacitive accelerometers that utilize an order of magnitude smaller gap size compared to conventional designs [10][11][12][13]. This methodology has enabled integration of accelerometer with different resonant sensors on a common substrate [9,10], stable operation under low-pressure level (1-10 Torr) [10,11], wide bandwidth [11] and improved sensitivity [12]. In this paper, we expand this methodology to implement single-proof-mass tri-axial accelerometer, which addresses the challenges mentioned above.…”

Section: Introductionmentioning

confidence: 99%

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A wide-bandwidth tri-axial pendulum accelerometer with fully-differential nano-gap electrodes

Jeong

Serrano

Ayazi

2018

J. Micromech. Microeng.

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This paper presents the implementation and characterization of a single proof-mass wide-bandwidth pendulum accelerometer with fully-differential sensitivity in all three axes. The utilization of nano-gap electrodes (300 nm) boosts the electromechanical coupling significantly so that both increased sensitivity and high resonant frequency (fres > 15 kHz) can be attained, which extends the operational bandwidth as well as the dynamic range of the device using a miniaturized proof-mass of 450 × 450 µm2. Furthermore, increased air-damping from the nano-gap structure enables the stable operation of the device at moderate vacuum environment (1–10 Torr), which paves the way toward the single-chip inertial measurement unit by integrating a quasi-static accelerometer with resonant gyroscopes on a common substrate. The presented design is fabricated on a 40 µm thick silicon-on-insulator substrate and wafer-level vacuum-packaged with a TSV substrate at a moderate vacuum level (1–10 Torr). The device, interfaced with a switched capacitor ASIC exhibits sub-milli-g noise levels in a wide bandwidth exceeding 10 kHz and bias instability of 560 µg, 428.16 µg, 145 µg for the X, Y and Z axes, respectively.

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Section: Design Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A wide-bandwidth tri-axial pendulum accelerometer with fully-differential nano-gap electrodes

Jeong

Serrano

Ayazi

2018

J. Micromech. Microeng.

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“…The recent works in the sensors field were based on the proposal of new designs for different types of accelerometers particularly the capacitive accelerometer taking into account other parameters than damping rate . In contrast, the present work has considered the damping rate effect as the main factor to improve many parameters at the same time such as measurement error, accuracy, sensitivity, reliability, and electrical energy consumption.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of capacitive accelerometer operation by parameters improvement

Ghemari

Saad

2019

Int J Numerical Modelling

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In the present paper, a mathematical model suitable for capacitive accelerometer is developed by applying the fundamental principle of dynamics and validated by simulation and experiment test. This model aims to visualize the capacitance variation of the accelerometer as a function of relative movement frequency. The main motivation key role of this paper is to propose a capacitive accelerometer with improved parameters. Therefore, in capacitive detection, the damping rate choice is directly influenced by the variation in capacitance; for this purpose, a comparative study of three damping rates is carried out. The first accelerometer is used in practical tests, the second is presented and studied in recent literature, and the third is the accelerometer proposed in this work. A new expression is extracted from the damping ratio as a function of measurement error to determine the damping rate according to a desired measurement error value. Finally, a new capacitive accelerometer with improved parameters having many advantages over the existing accelerometers is obtained. Simulation and experimental results have enabled us to recommend a new capacitive accelerometer design with very low measurement error (limited to 0.25%), high accuracy (equal to 99.75%), high sensitivity and reliability, and low electrical energy consumption.

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“…Using this sensor, we have been able to detect pathological S 3 heart sounds in patients with preexisting conditions while simultaneously measuring shallow breathing patterns. The devices are fabricated using a unique and high-precision fabrication technique, the high aspect-ratio combined poly-and single-crystal silicon micromachining technology (HARPSS), 33,34 to achieve ultrasensitive, wideband and triaxial capacitive vibration transducer. The sensor with ultrahigh aspect-ratio gaps of greater than 150, which cannot be fabricated with conventional fabrication methods, simultaneously benefits from functionalities of contact microphones and triaxial accelerometers to enable recording cardiopulmonary sounds, heart rate (using SCG 22 signals), respiration rate and physical activities of an individual.…”

Section: Introductionmentioning

confidence: 99%

Precision wearable accelerometer contact microphones for longitudinal monitoring of mechano-acoustic cardiopulmonary signals

et al. 2020

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Mechano-acoustic signals emanating from the heart and lungs contain valuable information about the cardiopulmonary system. Unobtrusive wearable sensors capable of monitoring these signals longitudinally can detect early pathological signatures and titrate care accordingly. Here, we present a wearable, hermetically-sealed high-precision vibration sensor that combines the characteristics of an accelerometer and a contact microphone to acquire wideband mechano-acoustic physiological signals, and enable simultaneous monitoring of multiple health factors associated with the cardiopulmonary system including heart and respiratory rate, heart sounds, lung sounds, and body motion and position of an individual. The encapsulated accelerometer contact microphone (ACM) utilizes nano-gap transducers to achieve extraordinary sensitivity in a wide bandwidth (DC-12 kHz) with high dynamic range. The sensors were used to obtain health factors of six control subjects with varying body mass index, and their feasibility in detection of weak mechano-acoustic signals such as pathological heart sounds and shallow breathing patterns is evaluated on patients with preexisting conditions.

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Low-Pressure Wafer-Level-Packaged Capacitive Accelerometers With High Dynamic Range and Wide Bandwidth Using Nano-Gap Sloped Electrode Design

Cited by 20 publications

References 24 publications

A wide-bandwidth tri-axial pendulum accelerometer with fully-differential nano-gap electrodes

A wide-bandwidth tri-axial pendulum accelerometer with fully-differential nano-gap electrodes

Enhancement of capacitive accelerometer operation by parameters improvement

Precision wearable accelerometer contact microphones for longitudinal monitoring of mechano-acoustic cardiopulmonary signals

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