3 research outputs found

    A Cost-Effective Geodetic Strainmeter Based on Dual Coaxial Cable Bragg Gratings

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    Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in their temporal or spatial resolutions. Here we present a new type of strainmeters based on the coaxial cable Bragg grating (CCBG) sensing technology that provides cost-effective strain measurements. Two CCBGs are introduced into the geodetic strainmeter: one serves as a sensor to measure the strain applied on it, and the other acts as a reference to detect environmental noises. By integrating the sensor and reference signals in a mixer, the environmental noises are minimized and a lower mixed frequency is obtained. The lower mixed frequency allows for measurements to be taken with a portable spectrum analyzer, rather than an expensive spectrum analyzer or a vector network analyzer (VNA). Analysis of laboratory experiments shows that the strain can be measured by the CCBG sensor, and the portable spectrum analyzer can make measurements with the accuracy similar to the expensive spectrum analyzer, whose relative error to the spectrum analyzer R3272 is less than ±0.4%. The outputs of the geodetic strainmeter show a linear relationship with the strains that the CCBG sensor experienced. The measured sensitivity of the geodetic strainmeter is about −0.082 kHz/ΌΔ; it can cover a large dynamic measuring range up to 2%, and its nonlinear errors can be less than 5.3%

    Fiber-optic and coaxial-cable extrinsic Fabry-Perot interferometers for sensing applications

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    ”The fiber-optic extrinsic Fabry-Perot interferometer (EFPI) is one of the simplest sensing configurations and is widely used in various applications due to its prominent features, such as high sensitivity, immunity to electromagnetic interference, and remote operation capability. In this research, a novel one-dimensional wide-range displacement sensor and a three-dimensional displacement sensor based on fiber-optic EFPIs are demonstrated. These two robust and easy-to-manufacture sensors expand the application scope of the fiber-optic EFPI sensor devices, and have great potential in structural health monitoring, the construction industry, oil well monitoring, and geo-technology. Furthermore, inspired by the fiber-optic EFPI, a novel and universal ultra-sensitive microwave sensing platform based on an open-ended hollow coaxial cable resonator (OE-HCCR, i.e., the coaxial cable EFPI) is developed. Both the theoretical predictions and experimental results demonstrate the ultra-high sensitivity of the OE-HCCR device to variations of the gap distance between the endface of the coaxial cable and an external metal plate. Additionally, combining the chemical-specific adsorption properties of metal-organic framework (MOF) materials with the dielectric sensitivity of the OE-HCCR, a mechanically robust and portable gas sensor device (OE-HCCR-MOF) with high chemical selectivity and sensitivity is proposed and experimentally demonstrated. Due to its low cost, high sensitivity, all-metal structure, robustness, and ease of signal demodulation, it is envisioned that the proposed OE-HCCR device will advance EFPI sensing technologies, revolutionize the sensing field, and enable many important sensing applications that take place in harsh environments”--Abstract, page iv

    A CMOS self-contained quadrature signal generator for soc impedance spectroscopy

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    This paper presents a low-power fully integrated quadrature signal generator for system-on-chip (SoC) impedance spectroscopy applications. It has been designed in a 0.18 ”m-1.8 V CMOS technology as a self-contained oscillator, without the need for an external reference clock. The frequency can be digitally tuned from 10 to 345 kHz with 12-bit accuracy and a relative mean error below 1.7%, thus supporting a wide range of impedance sensing applications. The proposal is experimentally validated in two impedance spectrometry examples, achieving good magnitude and phase recovery results compared to the results obtained using a commercial LCR-meter. Besides the wide frequency tuning range, the proposed programmable oscillator features a total power consumption lower than 0.77 mW and an active area of 0.129 mm2, thus constituting a highly suitable choice as stimulation module for instrument-on-a-chip devices
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