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A new torsional resonator is designed for the infrared sensor. The actuation uses the fringe field from the vertical sidewall. The electrostatic detection bases on the transmitted voltage to the electrode near to the resonator.
A system clock is implemented with a 2.52 GHz MEMS-based oscillator, divider, temperature sensor, digital PLL, and active temperature compensation to generate a 48 MHz frequency reference with ±10 ppm stability from −40°C to 105°C. An on-chip 32 kHz RC oscillator is also periodically calibrated by this reference clock to achieve ±500 ppm accuracy, allowing it to be used as the wireless node sleep...
A new configuration is presented for detecting a small-scale variation in liquid level. Here, a piezoelectric cylindrical resonator operating in a trapped-energy mode is employed instead of the plate-type resonators such as used in the former studies. It has been confirmed that steep variations in G on the dipping depth d is observed in the evanescent-field range.
Piezoresistive sensing has been regarded as an effective transduction method in MEMS resonator researches and piezoresistive micromechanical oscillators are therefore of great interests. The induced joule heating in the piezoresistive sensing, however, has a strong effect on the performance of the device. In this work, a micromechanical double ended tuning fork (DETF) based piezoresistive oscillator...
In this paper, prototypes of SC-cut resonators with 5 MHz resonant frequency are presented. The resulting short-term stability of some resonators has been measured lower than 8·10−-14 in terms of Allan standard deviation. The results are compared according to the overtone behavior on different vibrating modes to find a correlation with the intrinsic noise of the resonators. The comparison of these...
We propose a frequency drift detection method for coherent population trapping (CPT) atomic clocks to improve their long-term frequency stability. One of the main reasons for frequency drift in gas-cell based atomic clocks is buffer gas pressure variations in the gas cells caused by leakage through the cell walls. In this work, the drift detection method is demonstrated experimentally using a dual...
The miniaturization of resonators for timing applications brings with it new challenges in terms of device optimization. As the device size is reduced, design intolerances lead to more significant differences between modeled and fabricated devices leading to poor performance. In this paper we present a methodology for improving resonator designs. A 32MHz AT-cut quartz thick VHF shear mode resonator...
The acoustic wave (AW) sensors can response to a physical, chemical, or biological stimulus in a sensitive and real-time manner, so they have drawn increasing attraction in recent years. Among the AW sensors, the piezoelectric ones show a lot of extraordinary merits such as high resolution, wide frequency and temperature ranges, high stability, low power consumption, and low cost, and they are able...
A frequency reference system is implemented with a BAW-based 2.52GHz oscillator, divider, temperature sensor, digital PLL, and final test at three temperatures to create a 48MHz reference frequency with +/−10ppm stability from −40 to 125°C. This reference clock periodically recalibrates a fully integrated 32kHz RC oscillator to less than +/−500ppm frequency variation so that it can be used as the...
Whispering gallery mode thermometers (WGMTs) represent an attractive alternative to platinum resistance thermometers (PRTs) as transfer standards in industrial applications. Recent studies on the WGMT performance are also prompting its use as interpolating thermometers for the dissemination of the thermodynamic temperature scale. A low-cost and portable sapphire-based WGMT was recently developed and...
In order to measure the junction temperature of power equipment, a novel strategy of temperature measurement based on surface acoustic wave (SAW) passive wireless temperature sensor was designed. The antennas and the matching methods of antennas and sensors were also discussed. In this design, the reader antenna was designed as the planar inverted-F antenna (PIFA), and the sensor antenna was designed...
We study NaCl-water solutions as the temperature sensitive material for chipless RFID-based temperature threshold sensing, detecting and storing the event if a given threshold temperature is surpassed. Different solution concentrations are evaluated simultaneously with a sensor that can detect multiple temperature thresholds. A new method for background interference subtraction is presented, which...
Mining networks are subject to high requirements in terms of operational reliability and safety. The occurrence of ferroresonances in the network is one of the causes of instrument transformers being overloaded, which can cause their damage. Therefore, it is necessary to avoid this phenomenon and design the instrument transformers in a way so that even in the event of ferroresonance there is no damage...
This paper presents a real-time temperature compensation algorithm for a force-rebalanced MEMS capacitive accelerometer which relies on the linear relationship between the temperature and its dynamical resonant frequency. A phase-locked loop (PLL), where we inject a drive signal to excite the accelerometer into resonance and track the real-time resonant frequency, is added to the conventional force-rebalanced...
We report an electro-thermally tunable in-plane doubly-clamped nanoelectromechanical resonator capable of dynamically performing NOR, NOT, XNOR, XOR, and AND logic operations. Toward this, a silicon based resonator is fabricated using standard e-beam lithography and surface nanomachining of a highly conductive device layer of a silicon-on-insulator (SOI) wafer. The performance of this logic device...
Environmental temperature is essential for security monitoring and controlled areas, such as chemicals factory and Inflammable goods vehicle, in which WSN is the most appropriate choice for intelligent monitoring purpose. In this work, we design a piezoelectric energy harvester to collect low-acceleration (<0.5 g) and low-frequency (<50 Hz) vibration energy for powering wireless sensor network...
Temperature monitoring of tools is one key method for the prediction and detection of tool failure to prevent damage of valuable workpieces, e. g. in aircraft manufacturing. Therefore, a chipless wireless dielectric temperature sensor for machine tools, with very high temperature capability and compatibility to the harsh machine tool environment, is investigated. Based on these findings, a demonstrator...
This paper reports a frequency modulated (FM)/rate integrating MEMS gyroscope where superposed clockwise (CW) and counter clockwise (CCW) modes are independently controlled on a single resonator. A frequency and quality factor mismatch compensation method by adjusting the phases and amplitudes of driving signal is proposed and experimentally demonstrated. The mismatch compensation method proposed...
A simple cavity resonator is described for measuring surface resistance (Rs) of high temperature superconductor (HTS) thin films. The cavity is a one-half wavelength of WR-28 waveguide with the HTS forming a short across one end. A choke ring reduces the need for low resistance contact. Quantitative Rs measurements can be made over the range of 10 mΩ to 500 mΩ at liquid nitrogen temperature and at...
In this work, we propose a novel temperature compensation method that utilizes a tri-mode operation scheme to generate a temperature-stable frequency reference over a large temperature range. Three resonant modes are excited simultaneously on a highly doped silicon MEMS resonator, and the unique TCf characteristic of each mode is fitted to a parabolic curve. A linear combination of the three frequencies...
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