Resonance Frequency Of Sensor Research Articles

Metamaterial absorber‐based sensor embedded into X‐band waveguide

A novel metamaterial sensor, integrated with an X-band waveguide, is proposed for high-resolution measurements of variations in the dielectric constant and/or the thickness of a superstrate layer that covers a pair of absorber unit cells. Variations in superstrate parameters are potentially caused by physical, chemical or biological factors, and can be detected by measuring the corresponding shifts in the resonance frequency of the metamaterial sensor. It is estimated by simulation results that resolution levels as good as 1.1 μm change in thickness or 0.023 absolute change in relative permittivity of the sensing layer are feasible for a 10 MHz measurable shift in resonance frequency. Simulation results obtained for the fabricated prototype are verified experimentally with good agreement.

A distributed piezo-polymer scour net for bridge scour hole topography monitoring

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

Characterization of drying behavior of granular materials using magnetoelastic sensors

The aim of the present paper is to show that magnetoelastic sensors can furnish important information about the drying behavior of ceramic materials, and are, therefore, possible alternatives to ultrasonic or cantilever techniques. Sensitive measurements of the resonant frequency of coated amorphous ribbons show characteristic structures at different phases of drying. A model relating the resonant frequency of a magnetoelastic sensor to elastic properties of an applied thin film coating is extended to include the magnetic field dependence of the elastic modulus, the ΔE effect. In this manner, the stress developed during the drying process which contributes to the magnetic anisotropy, can be introduced into the problem. The model is applied to hard clay slurries drying on Metglas 2826MB3 ribbons. The long time value of the sensor resonant frequency is found to be consistent with elastic properties of the clay and the sensor appropriately indicates the appearance of stresses when the meniscus of the drying fluid begins to enter the pores of the solid.

Passive wireless pressure sensor fabricated in low-temperature co-fired ceramic technology

A passive wireless pressure sensor based on low-temperature co-fired ceramic was investigated. The sensor is equivalent to a LC resonant circuit, which has a planar spiral inductor and an interdigital capacitor electrically connected. The inductor and capacitor are fabricated by screen printing technology. The working principle of the sensor is based on the pressure-sensitive resonant frequency of the LC circuit. Wireless detection can be realized by electromagnetic coupling with two inductor coils. The results show that the resonant frequency of sensor decreases with the increase in pressure, and sensitivity of the sensor is about 412.32 kHz/bar.

Impact of thermal frequency drift on highest precision force microscopy using quartz-based force sensors at low temperatures.

In frequency modulation atomic force microscopy (FM-AFM) the stability of the eigenfrequency of the force sensor is of key importance for highest precision force measurements. Here, we study the influence of temperature changes on the resonance frequency of force sensors made of quartz, in a temperature range from 4.8–48 K. The sensors are based on the qPlus and length extensional principle. The frequency variation with temperature T for all sensors is negative up to 30 K and on the order of 1 ppm/K, up to 13 K, where a distinct kink appears, it is linear. Furthermore, we characterize a new type of miniaturized qPlus sensor and confirm the theoretically predicted reduction in detector noise.

A New Readout System for LC Resonant Sensors

A new readout system based on LC resonant sensor is presented. The readout system consists of a reader coil inductively coupled to the LC resonant sensor, a measurement unit, and a PC post processing unit. The measurement unit generates an output voltage representing the sensor resonance, converts the output voltage to numerical form, and saves the converted digital data. The PC post processing unit processes the digital data and calculates the sensor's resonance frequency. The readout system enables wireless interrogation and its accuracy is exemplified by an experimental system. The experimental system can detect the resonant frequency of sensor automatically and effectively. The experimental results are presented for different sensor resonance frequencies with various sensor capacitance values and show good agreement with the theoretical results. The entire design is simple, easy to use, and widely applicable for applications where the coupling distance between sensor and reader coil is variable.

Salmonella Typhimurium Detection on Fresh Food Surfaces Using a Surface-Scanning Coil Detector and Magnetoelastic Sensors

This study presents results from an investigation into the rapid, sensitive, real-time direct detection of Salmonella Typhimurium on food surfaces. The biosensor consists of a freestanding, strip-shaped magnetoelastic (ME) resonator as the signal transducer and E2 phage as the bio-molecular recognition element that selectively binds with S. Typhimurium (1). The ME resonator is a class of mass-sensitive biosensor that can be wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field (2). When the biosensor binds with S. Typhimurium, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency (3). We have previously reported the possible use of ME biosensors for the detection of pathogenic bacteria on food surfaces (4). This new detection system consists of a planar spiral coil that excites and measures the resonant frequency of freestanding ME biosensors on the surface of fruits and vegetables (5). Multiple E2 phage-coated biosensors (measurement sensors) were placed on the food surfaces spiked with S. Typhimurium of various concentrations. Control sensors without phage were also used to compensate for environmental effects and non-specific binding. During binding with the bacteria, the resonant frequency of the sensor was wirelessly measured in real time. This frequency change is directly proportional to the mass of the bacteria bound to the sensor surface. References S. Horikawa, D. Bedi, S. Li, W. Shen, S. Huang, I. Chen, Y. Chai, M. L. Auad, M. J. Bozack, J. M. Barbaree, V. A. Petrenko, and B. A. Chin, 2011. Biosensors and Bioelectronics, Vol. 26(5), 2361-2367.Y. Chai, H. C. Wikle, Z. Wang, S. Horikawa, S. Best. Z. Cheng, D. F. Dyer and B. A. Chin, 2013. Journal of Applied Physics, Vol. 114, 104504.Y. Chai, S. Li, S. Horikawa, M. Park, V.J. Vodyanoy and B. A. Chin. 2012. Journal of Food Protection, Vol. 75(4), 631-636.Y. Chai, S. Horikawa, H. C. Wikle, Z. Wang and B. A. Chin, 2013. Applied Physics Letters, Vol. 103, 173510.Y. Chai, S. Horikawa, S. Li, H. C. Wikle, and B. A. Chin, 2013. Biosensor and Bioelectronics, Vol. 50, 311-317.

High temperature characteristic for wireless pressure LTCC-based sensor

The high temperature characteristic for pressure sensor based on low-temperature co-fired ceramic (LTCC) technology is researched. The Young's modulus of LTCC DuPont 951 ceramic versus temperature is analysed theoretically. The sensor resonant frequency is tested from room temperature to 600 °C. Results show that resonant frequency drops nearly as a line. And the dropping of resonant frequency is mainly caused by the increase of LTCC material permittivity. A capacitor structure is proposed to reduce the change of frequency versus temperature and a compensation structure is proposed for the actual application. Moreover, the coupling effect between antenna and sensor fabricated using FERRO A6M-E and DuPont 951 is compared at 600 °C. Result shows that the material with lower dielectric loss and thermal conductivity is suggested to increase the temperature range of operation of sensor.

Frequency analysis of ultrasonic wave propagation on metal pipe in ultrasonic tomography system

Purpose – Since the importance role of ultrasonic tomography (UT) in industry, especially in oil industry, to produce noninvasive and nondestructive plane images, research on UT system with a metal pipe conveyor is investigated. The produced cross-sectional images are used for detecting the concentration of solid and liquid mixture inside the pipe, noninvasively. In practice, due to application of metal pipes as the conveyor of oil mixture so the capability of manufacturing an UT system with a metal pipe is investigated in this paper. The paper aims to discuss these issues. Design/methodology/approach – Finite element software (COMSOL Multiphysics 3.5) for visualizing the structure of pipe with mounted sensors on the periphery of the pipe is used. The manner of ultrasonic wave propagation on different layers on various frequencies and finding the time of flight for transmission mode signal and lamb mode signal are achieved by the means of done simulations. Finding the proper ultrasonic sensor base on its efficiency is the main step of designing an UT system. This is done by estimating the resonance frequency of sensor due to the manner of ultrasonic wave propagation in different frequencies shown in simulation results. Findings – Due to simulation results, lamb wave is a permanent propagation mode of ultrasonic wave which makes interference in measuring process of straight path signal and it is impossible to remove. Relief of the mentioned problem finding an optimum frequency to decrease the affection of lamb wave in detecting point. Optimum frequency of ultrasonic wave to satisfy the objective is 45 kHz which is measured by considering of mathematic of ultrasonic wave propagation in different layers. The reaching time of straight path signal and lamb wave signal in opposite sensor as the receiver are 5.5 and 4.6 μs, respectively. Originality/value – This investigation is the first step to perform the UT in a noninvasive method to produce the cross-sectional images of metal pipe. Due to the wide application of metal pipes as the conveyor of the liquids/gases, metal pipe for the UT application is studied in this research.

A DDS-based Multi-harmonic Frequency Meter for QCM Sensor Applications

In this paper we present a prototype of a frequency meter based on an ARM processor and a DDS module. The instrument was developed to be used with QCM-sensor based oscillator circuits for in-liquid applications. For each resonance frequency of the QCM sensor, up to 50MHz, the instrument can generate a reference signal exploiting the DDS module, which is used to perform a heterodyne demodulation of the oscillator signal. The ARM processor is used to on-line change the DDS settings (to track up to three resonance frequencies components with interleaved sampling of the QCM signals with a sampling time of about 1s) and to perform the frequency measurements. The contemporary use of the information from different QCM resonance frequencies will be exploited to enhance the instrument sensitivity while preserving a resolution of about 1Hz for short term measurements with 10MHz QCMs. At present, preliminary tests were performed.

A readout system for passive pressure sensors

This paper presents a readout system for the passive pressure sensors which consist of a pressure-sensitive capacitor and an inductance coil to form an LC circuit. The LC circuit transforms the pressure variation into the LC resonant frequency shift. The proposed system is composed of a reader antenna inductively coupled to the sensor inductor, a measurement circuit, and a PC post-processing unit. The measurement circuit generates a DC output voltage related to the sensor's resonant frequency and converts the output voltage into digital form. The PC post-processing unit processes the digital data and calculates the sensor's resonant frequency. To test the performance of the readout system, a sensor is designed and fabricated based on low temperature co-fired ceramic (LTCC), and a series of testing experiments is carried out. The experimental results show good agreement with the impedance analyzer's results, their error is less than 2.5%, and the measured values are almost insensitive to the variation of readout distance. It proves that the proposed system is effective practically.

100 kHz MEMS Vibratory Gyroscope

The behavior of MEMS rate gyroscopes depends on the sensor's resonance frequency f0. Key features like robustness against external vibrations and ease of integration can be optimized by increasing f0. We designed and fabricated a device with f0=100 kHz for experimental and theoretical investigation of MEMS vibratory gyroscopes with increased f0. The frequency of 100 kHz is significantly above the typical f0 of current gyroscopes which is in the range of 10 kHz to 30 kHz. Measurements prove that key parameters that are theoretically derived from a 15 kHz reference model can be scaled to 100 kHz with good accuracy. It is shown that the increase of f0 to 100 kHz has-on the one hand-design trade offs like a much lower sensitivity and higher quadrature and-on the other hand-major advantages like the significantly improved vibration robustness.

Flexible and Surface-Mountable Piezoelectric Sensor Arrays for Underwater Sensing in Marine Vehicles

In an effort to improve the situational awareness and obstacle avoidance of marine vehicles, we fabricate, package and characterize Pb (Zr0.52Ti0.48)O3 thin-film piezoelectric pressure sensor arrays for passive fish-like underwater sensing. We use floating bottom electrode in designing the sensor which made the sensor able to detect very low frequency range (down to 0.1 Hz) in water. The proposed array of sensors is capable of locating underwater objects by transducing the pressure variations generated by the stimulus. The sensors are packaged into an array of 2 × 5 on a flexible liquid crystal polymer substrate patterned with gold interconnects. Experiments in this paper are divided into three main categories. First, in order to evaluate the effect of water on the sensor performance, resonant frequency, and quality factor changes in air and water are investigated theoretically and experimentally. Second, the ability of the array in locating a vibrating sphere (dipole) in water is illustrated through experiments. The sensors demonstrate a high resolution of 3 mms <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> in detecting in detecting oscillatory flow velocity in water. Third, “real-time” experiments are conducted in a swimming pool environment by surface mounting two arrays of sensors on the curved hull of a kayak vehicle. The arrays are self-powered and do not need any external power supply, to operate, which greatly benefits in eliminating the need of bulky power supplies on underwater vehicles.

Force Sensor and its Application to Tuning Fork Response Measurement

Generally, force measurement of nanoscale material widely employs a quartz tuning fork which is resonant mechanical sensors on 32.768 kHz resonance frequency and is powerful tools. But, this paper designs the sensor by using tuning fork on 3 kHz and modifies the tuning fork by a tiny pin adhesive into the end of prong. In experiment, measurements of electrical signal from piezoelectric are study of load-mass effect and pin position. 2 touching techniques are considered: a shear-force type and a tapping mode type with highly position movement system. Silicone rubber, vinyl eraser and hydrogel are elastic material for testing. Results show that both weight and position of pin is significant influencer for resonance frequency and quality factor of sensor. Finally, the tuning fork response experimentation shown this method can be applied to material classification.

Piezoelectric-metal-magnet dc magnetoelectric sensor with high dynamic response

A dc magnetoelectric sensor capable of measuring both dc and ac magnetic fields is developed by combining a thickness-polarized 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) piezoelectric single-crystal plate, a pair of electrically connected aluminum strips, and a pair of NdFeB magnet plates in orthogonal directions. The operation of the sensor is based on the mechanical mediation of the magnetically biased Lorentz force effect in the aluminum strips due to a drive magnetic field (B3D) applied to the sensor, a dc bias magnetic field (B3B) preset by the NdFeB plates, and an ac reference electric current (I2) flowing through the aluminum strips with the transverse piezoelectric effect in the PMN–PT plate at the sensor resonance. The theoretical and experimental results confirm an ultrahigh and linear current-controlled magnetic field sensitivity of 1.7 V/T/A in broad ranges of B3D amplitude of −100 to 100 mT and B3D frequency of 0–15 kHz by using an I2 of ≤100 mA at the sensor resonance frequency of 65 kHz.

Acoustic detection of cell adhesion to a coated quartz crystal microbalance – implications for studying the biocompatibility of polymers

Biocompatibility of polymers is an important parameter for the successful application of polymers in tissue engineering. In this work, quartz crystal microbalance (QCM) devices were used to follow the adhesion of NIH 3T3 fibroblasts to QCM surfaces modified with fibronectin (FN) and poly-D-lysine (PDL). The variations in sensor resonant frequency (Δf) and motional resistance (ΔR), monitored as the sensor signal, revealed that cell adhesion was favored in the PDL-coated QCMs. Fluorescence microscopy images of seeded cells showed more highly spread cells on the PDL substrate, which is consistent with the results of the QCM signals. The sensor signal was shown to be sensitive to extracellular matrix (ECM)-binding motifs. Ethylenediaminetetraacetic acid (EDTA) and soluble Gly-Arg-Gly-Asp-Ser (GRGDS) peptides were used to interfere with cell-ECM binding motifs onto FN-coated QCMs. The acquired acoustic signals successfully showed that in the presence of 30 mM EDTA or 1 mM GRGDS, cell adhesion is almost completely abolished due to the inhibition/blocking of integrin function by these compounds. The results presented here demonstrate the potential of the QCM sensor to study cell adhesion, to monitor the biocompatibility of polymers and materials, and to assess the effect of adhesion modulators. QCM sensors have great potential in tissue engineering applications, as QCM sensors are able to analyze the biocompatibility of surfaces and it has the added advantage of being able to evaluate, in situ and in real time, the effect of specific drugs/treatments on cells.

Signal Optimization for Salmonella Typhimurium Detection on Food Surfaces Using Phage-Based Biosensors

This paper presents the direct detection of Salmonella typhimurium on egg shells using a phage-based magnetoelastic (ME) biosensor. The ME biosensor consists of an ME resonator as the sensor platform and E2 phage as the bio-recognition element. The bio-recognition element is genetically engineered to bind specifically with Salmonella typhimurium. The ME biosensor, a wireless sensor, vibrates with a characteristic resonant frequency under an externally applied magnetic field. Multiple sensors can easily be remotely monitored. Multiple measurement and control sensors were placed on egg shells contaminated by Salmonella typhimurium solutions with different known concentrations. The resonant frequency of sensors before and after the exposure to the spiked egg shells was measured. The frequency shift of the measurement sensors was significantly different than the control sensors indicating Salmonella contamination. Scanning electron microscopy was used to confirm binding of Salmonella to the sensor surface and the resulting frequency shift results.

Various Designs of Meander Inductor and their Influence on LC Resonant Displacement Sensor

This paper deals with various configurations of meander inductor and their influence on characteristics of passive LC displacement sensor. Passive techniques use LC resonator to measure the parameters of interest remotely without an on-board power supply. Developed LC sensor comprises a fixed meander inductor and a movable module of mender inductor - interdigital capacitor resonant circuit, thereby causing the sensor resonant frequency to be displacement - dependent. The inductor and sensor circuits have been fabricated in PCB technology. The main goal was to find the optimal position for measurement connection pads on fixed meander inductor PCB as well as position of connection line between mender inductor and interdigital capacitor on PCB board with LC circuit. Measurements were realized on Impedance Analyzer (HP4191A) in frequency range from 10 MHz to 30 MHz, with 100 kHz step for each configuration of meander inductor. As results of these measurements the best configuration and the best sensor sensitivity for both mender inductors was determined.

Insulation by Solution 3-Mercaptopropyltrimethoxysilane (MPS) Coating: Effect of pH, Water, and MPS Content

We have investigated the effect of 3-mercaptopropyltrimethoxysilane (MPS) concentration, water content, and pH on the thickness and insulation quality of a MPS coating layer on a gold electrode obtained in an MPS solution in ethanol. We showed that controlling the MPS concentration, water content, and pH were all important for the insulation coating. With 1% MPS and 0% water, the coating rate remained well below 1 nm/h at all pH and at 2 and 8 nm/h in 0.1% MPS with 0.5% water at pH 9 and in 1% MPS with 1% water at pH 9, respectively. Furthermore, the surface of the MPS coating obtained with 0.1% MPS and 0.5% water at pH 9 was smooth for optimal binding surface stress induced detection resonance shift in a piezoelectric plate sensor. The width-mode resonance frequency of a piezoelectric plate sensor insulated with a MPS coating obtained in 0.1% MPS with 0.5% water at pH 9 for 36 h was shown to be stable for more than 24 h in a phosphate buffered saline solution.

Ultrasonic Tomography System: Optimizing the Frequency in a Metal Pipe Conveyor

Ultrasonic Tomography has a dominant role in industry to generate cross sectional images of any object. In this paper, method of designing an Ultrasonic Tomography System due to the propagation manner of ultrasonic wave inside the various materials is investigated. The correct method of mounting of Ultrasonic sensors and behavior of the ultrasonic wave propagation in different layers has been simulated by the use of finite element software (COMSOL Multiphysics 3.5). To increase in practical nondestructive evaluation and inspection, we should increase our understanding of the basic physics and wave mechanics associated with guided wave inspection. A suitable ultrasonic sensor base on its efficiency and satisfying the simulation criteria is found and practically implemented on the surface of metal pipe. it is done by estimating the resonance frequency of sensor due to manner of ultrasonic wave propagation in different frequencies shown in simulation results. The proposed optimum frequency for the applied sensors is 40 kHz in which is tested practically and experimental results prove the high efficiency of this system.