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A novel scheme of voltage controlled temperature compensated crystal oscillator (VCTCXO) which could realize frequency adjustment and temperature compensation simultaneously is presented. The scheme is based on the binary function V = F(T, ft) which could be obtained from the temperature experiments, where ft is the target output frequency (controlled and adjusted by external control voltage); T is...
This paper presents a hybrid passive wireless resonant electrical and mechanical sensor for enhanced sensitivity and specificity. Mechanical resonance measures the viscosity and electrical resonance measures the dielectric properties of liquid samples. The sensor is composed of two magnetoelastic (amorphous ferromagnetic ribbons) strips placed in parallel that are separated with a dielectric spacer...
This work presents a passive resonant micro-electromechanical phase detector (PD). The PD structure is comprised of two thin film piezoelectric on silicon (TPoS) resonator plates coupled by a silicon beam in the middle. The device exhibits a width extensional resonance mode in which resonant plates vibrate out of phase. When actuated in this mode, the interference of acoustic waves generated from...
Pressure measurements provide reliable estimates of the reservoir pressure, permeability and oil/water interface in reservoirs that help in optimal completion of wells for oil and gas production. Pressure sensors with high accuracy, resolution, and fast response time are necessary for characterizing highly permeable reservoirs. High precision pressure sensors are generally, made of crystalline quartz...
In this paper the linear temperature coefficient of frequency in bulk-extensional MEMS resonators is reduced utilizing a relatively thin layer of sputtered Fluorine-doped silicon dioxide (SIOF). The Fluorine doping is achieved through addition of a Fluorine-containing gas in the Ar/O2 gas mixture of a typical SiO2 RF magnetron sputtering process. Our preliminary results indicate that the temperature...
Two kinds of new silicon actuators, cantilever and twisted-beam, based on pn diode actuation principle are presented. The space gap that is absolutely needed in conventional electrostatic MEMS actuators is replaced by a depletion layer in reversely-biased pn diode. The strong electric field generated in the depletion layer forces a silicon microstructure to vibrate. The microstructure causes a large...
Resonant SAW strain sensing elements used in non-contact torque, force and vibration sensors are investigated from the point of view of their stability and durability. Results of fatigue testing of the SAW sensing elements bonded to metal shafts with a stiff adhesive are presented. They demonstrate the sensor durability and stability of the strain sensitivity up to 13 million strain cycles. Stability...
In this paper we introduce enhanced low power clock system that is able to achieve frequency stability ±0.01 ppm over a wide temperature range, which is approximately 100 times better than the stability achievable with typical Temperature Compensated Crystal Oscillator (TCXO). The proposed clock system is based on Dual-Mode Crystal Oscillator (DMXO) and the Chip Scale Atomic Clock (CSAC). Power consumption...
Microwave sensors play a significant role in medical environments. The contact-less and non-invasive sensing mechanism to determine the dielectric properties of tissue is of great advantage. In this work, a dual mode microwave sensor is designed to combine the diagnosis and treatment of cancer in one minimal invasive surgery tool. In order to detect abnormalities, the relative change of permittivity...
This work explores the use of thermo-acoustic coolers as alternative technology for refrigeration. A valid experimental evidence on the influence of the geometry of the honeycomb ceramic stack on the performance of thermos-acoustic refrigerators is described. Sixteen cordierite honeycomb ceramic stacks with square cross sections having four different lengths of 26 mm, 48 mm, 70 mm and 100 mm are considered...
It is well known that the rate bias sensitivity to temperature is one of the principal sources of error for MEMS gyros. Frequency locking the gyro resonant frequency to a reference clock using local, low time constant, ovenization as a feedback mechanism has been proposed as a method to greatly improve the stability of gyros under dynamical thermal changes. In order to assess how effective such methods...
This study reports a temperature compensation method for a capacitive MEMS accelerometer by using a MEMS double-ended-tuning-fork (DETF) resonator integrated with the accelerometer structure on the same die. The proposed method utilizes the frequency information of the clamped-clamped DETF resonator which is oscillating in a closed-loop operation. In order to compensate the temperature dependence...
Precision MEMS oscillators require a temperature-to-digital converter (TDC) that adjusts the multiplication factor of a fractional-N PLL in order to compensate for the MEMS resonator's frequency variation over temperature [1]. This compensation, however, provides a path for the TDC's noise to propagate to the oscillator's output as phase noise (PN). Previous work has sought to minimize this noise,...
Wireless nodes in Internet-of-Everything (IoE) applications achieve low power consumption by operating the radio at very low duty cycles. The wireless node spends most of its time in sleep, waking only occasionally to transmit or receive data. For some standards, such as Bluetooth Low Energy (BLE), the data or advertising packet length can be less than the time it takes the crystal oscillator, which...
This work presents a micro-ovenized 77.7 MHz silicon MEMS oscillator using resonator's structural resistance as an embedded temperature sensor. The structural resistance of a silicon microresonator exhibits a large temperature coefficient of resistance (TCR) and is used as a sensitive self-temperature sensor to accurately and locally monitor resonator's temperature. A novel cross-sectional Lamé-mode...
In this paper, we report on the design, simulation and experimental validation of a miniaturized device that can generate multiple jet flows circulated in a confined system. The device has a flow network comprised of four symmetrical working chambers connected with a pump chamber which is actuated by a PZT diaphragm. The flows in the device are simulated using OpenFOAM and actual performance of the...
A Micro-electromechanical systems (MEMS) sensor with the variable cross-section micro-cantilever was designed to measure the fluid viscosity. Due to the quality factor of micro-cantilever under the torsional resonance is much higher than that under the first order flexural resonance, the fluid viscosity measuring accuracy under the torsional resonance is much higher. Then an exciting method named...
In this paper, first experiments regarding characterization of the GaN based FBAR (Film Bulk Acoustic Resonator) structures as pressure sensors are presented. The FBAR structures have been manufactured on GaN/Si using advanced micromachining technologies. The experiments have demonstrated the excellent mechanical properties of 0.5 µm thin GaN membranes able to support a pressure of at least 5 Bar.
For practical applications of quartz crystal resonators, accurate estimation of the aging pattern and adoption of appropriate correction procedure will be important in ensuring the precise operating condition and maintaining their optimal performance. There are two generally accepted aging models for the prediction of long-term behavior of quartz crystal resonators. The Arrhenius model is universally...
The temperature monitoring is important for the safety of power station. In this paper, a surface acoustic wave sensor was designed for measuring the temperature of high voltage switchgear in the power station. The coupling of modes analysis was used for simulating the device and a SAW resonator was fabricated based on the simulation result, which had sharp peak and large amplitude of S11. The sensor...
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