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Special Issue "Resonator Sensors"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (31 August 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Stephane Evoy

Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
Website | E-Mail

Special Issue Information

Dear Colleagues,

Micromechanical devices have been proposed as highly-sensitive transducers for the rapid detection and assaying of molecular systems. More specifically, resonant sensors operate by monitoring shifts of resonance frequencies associated to the binding of analytes or under the action of an external force. Such an approach enables the frequency modulation of the output, thus greatly improving the stability/noise-immunity of the reading. Resonant sensor platforms include microcantilevers, quartz crystal microbalance (QCM), bulk acoustic wave resonators (FBARs), and nanomechanical devices. This Special Issue invites contributions on all aspects of resonant sensors, such as related materials science, fabrication platforms, transduction phenomena, and systems integration. Applications include, but are not limited to, biological detection, molecular assaying, gas detection, as well as the sensing of physical forces, such as acceleration, magnetic and electrical fields, and nuclear phenomena.

Prof. Dr. Stephane Evoy
Guest Editor

Manuscript Submission Information

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Keywords

  • Resonators
  • Cantilevers
  • Quartz Crystal Microbalance
  • Bulk Acoustic Wave Resonators
  • Nanoelectromechanical Systems

Published Papers (17 papers)

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Research

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Open AccessArticle
Dielectrically-Loaded Cylindrical Resonator-Based Wireless Passive High-Temperature Sensor
Sensors 2016, 16(12), 2037; https://doi.org/10.3390/s16122037
Received: 14 August 2016 / Revised: 18 November 2016 / Accepted: 24 November 2016 / Published: 1 December 2016
Cited by 7 | PDF Full-text (4337 KB) | HTML Full-text | XML Full-text
Abstract
The temperature sensor presented in this paper is based on a microwave dielectric resonator, which uses alumina ceramic as a substrate to survive in harsh environments. The resonant frequency of the resonator is determined by the relative permittivity of the alumina ceramic, which [...] Read more.
The temperature sensor presented in this paper is based on a microwave dielectric resonator, which uses alumina ceramic as a substrate to survive in harsh environments. The resonant frequency of the resonator is determined by the relative permittivity of the alumina ceramic, which monotonically changes with temperature. A rectangular aperture etched on the surface of the resonator works as both an incentive and a coupling device. A broadband slot antenna fed by a coplanar waveguide is utilized as an interrogation antenna to wirelessly detect the sensor signal using a radio-frequency backscattering technique. Theoretical analysis, software simulation, and experiments verified the feasibility of this temperature-sensing system. The sensor was tested in a metal-enclosed environment, which severely interferes with the extraction of the sensor signal. Therefore, frequency-domain compensation was introduced to filter the background noise and improve the signal-to-noise ratio of the sensor signal. The extracted peak frequency was found to monotonically shift from 2.441 to 2.291 GHz when the temperature was varied from 27 to 800 °C, leading to an average absolute sensitivity of 0.19 MHz/°C. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Design and Fabrication of Micro Hemispheric Shell Resonator with Annular Electrodes
Sensors 2016, 16(12), 1991; https://doi.org/10.3390/s16121991
Received: 27 August 2016 / Revised: 11 November 2016 / Accepted: 21 November 2016 / Published: 25 November 2016
Cited by 5 | PDF Full-text (6477 KB) | HTML Full-text | XML Full-text
Abstract
Electrostatic driving and capacitive detection is widely used in micro hemispheric shell resonators (HSR). The capacitor gap distance is a dominant factor for the initial capacitance, and affects the driving voltage and sensitivity. In order to decrease the equivalent gap distance, a micro [...] Read more.
Electrostatic driving and capacitive detection is widely used in micro hemispheric shell resonators (HSR). The capacitor gap distance is a dominant factor for the initial capacitance, and affects the driving voltage and sensitivity. In order to decrease the equivalent gap distance, a micro HSR with annular electrodes fabricated by a glassblowing method was developed. Central and annular cavities are defined, and then the inside gas drives glass softening and deformation at 770 °C. While the same force is applied, the deformation of the hemispherical shell is about 200 times that of the annular electrodes, illustrating that the deformation of the electrodes will not affect the measurement accuracy. S-shaped patterns on the annular electrodes and internal-gear-like patterns on the hemispherical shell can improve metal malleability and avoid metal cracking during glass expansion. An arched annular electrode and a hemispheric shell are demonstrated. Compared with HSR with a spherical electrode, the applied voltage could be reduced by 29%, and the capacitance could be increased by 39%, according to theoretical and numerical calculation. The surface roughness of glass after glassblowing was favorable (Rq = 0.296 nm, Ra = 0.217 nm). In brief, micro HSR with an annular electrode was fabricated, and its superiority was preliminarily confirmed. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
A Wideband Circularly Polarized Antenna with a Multiple-Circular-Sector Dielectric Resonator
Sensors 2016, 16(11), 1849; https://doi.org/10.3390/s16111849
Received: 22 August 2016 / Revised: 27 October 2016 / Accepted: 28 October 2016 / Published: 3 November 2016
Cited by 2 | PDF Full-text (1175 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30 but with different radii. A genetic algorithm is utilized to optimize [...] Read more.
This paper presents the design of a wideband circularly polarized antenna using a multiple-circular-sector dielectric resonator (DR). The DR is composed of twelve circular-sector DRs with identical central angles of 30 but with different radii. A genetic algorithm is utilized to optimize the radii of the twelve circular-sector DRs to realize wideband circular polarization. The proposed antenna is excited using an aperture-coupled feeding technique through a narrow rectangular slot etched onto the ground plane. An antenna prototype is experimentally verified. The measured −10 dB reflection and 3 dB axial ratio (AR) bandwidths are 31.39% (1.88–2.58 GHz) and 19.30% (2.06–2.50 GHz), respectively, covering the operating bands of the following systems: UMTS-2100 (2.145 GHz), WiMAX (2.3 GHz), and Wi-Fi (2.445 GHz). A measured peak gain of 7.65 dBic at 2.225 GHz and gain variation of less than 2.70 dBic within the measured 3 dB AR bandwidth are achieved. In addition, the radiation patterns of the proposed antenna are presented and discussed. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Whispering Gallery Mode Thermometry
Sensors 2016, 16(11), 1814; https://doi.org/10.3390/s16111814
Received: 1 September 2016 / Revised: 18 October 2016 / Accepted: 25 October 2016 / Published: 29 October 2016
Cited by 4 | PDF Full-text (8668 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a state-of-the-art whispering gallery mode (WGM) thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a [...] Read more.
This paper presents a state-of-the-art whispering gallery mode (WGM) thermometer system, which could replace platinum resistance thermometers currently used in many industrial applications, thus overcoming some of their well-known limitations and their potential for providing lower measurement uncertainty. The temperature-sensing element is a sapphire-crystal-based whispering gallery mode resonator with the main resonant modes between 10 GHz and 20 GHz. In particular, it was found that the WGM around 13.6 GHz maximizes measurement performance, affording sub-millikelvin resolution and temperature stability of better than 1 mK at 0 °C. The thermometer system was made portable and low-cost by developing an ad hoc interrogation system (hardware and software) able to achieve an accuracy in the order of a few parts in 109 in the determination of resonance frequencies. Herein we report the experimental assessment of the measurement stability, repeatability and resolution, and the calibration of the thermometer in the temperature range from −74 °C to 85 °C. The combined standard uncertainty for a single temperature calibration point is found to be within 5 mK (i.e., comparable with state-of-the-art for industrial thermometry), and is mainly due to the employed calibration setup. The uncertainty contribution of the WGM thermometer alone is within a millikelvin. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities
Sensors 2016, 16(10), 1730; https://doi.org/10.3390/s16101730
Received: 17 August 2016 / Revised: 3 October 2016 / Accepted: 12 October 2016 / Published: 18 October 2016
Cited by 8 | PDF Full-text (3237 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance [...] Read more.
In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM) value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Effectiveness Testing of a Piezoelectric Energy Harvester for an Automobile Wheel Using Stochastic Resonance
Sensors 2016, 16(10), 1727; https://doi.org/10.3390/s16101727
Received: 26 August 2016 / Revised: 6 October 2016 / Accepted: 13 October 2016 / Published: 17 October 2016
Cited by 14 | PDF Full-text (5420 KB) | HTML Full-text | XML Full-text
Abstract
The collection of clean power from ambient vibrations is considered a promising method for energy harvesting. For the case of wheel rotation, the present study investigates the effectiveness of a piezoelectric energy harvester, with the application of stochastic resonance to optimize the efficiency [...] Read more.
The collection of clean power from ambient vibrations is considered a promising method for energy harvesting. For the case of wheel rotation, the present study investigates the effectiveness of a piezoelectric energy harvester, with the application of stochastic resonance to optimize the efficiency of energy harvesting. It is hypothesized that when the wheel rotates at variable speeds, the energy harvester is subjected to on-road noise as ambient excitations and a tangentially acting gravity force as a periodic modulation force, which can stimulate stochastic resonance. The energy harvester was miniaturized with a bistable cantilever structure, and the on-road noise was measured for the implementation of a vibrator in an experimental setting. A validation experiment revealed that the harvesting system was optimized to capture power that was approximately 12 times that captured under only on-road noise excitation and 50 times that captured under only the periodic gravity force. Moreover, the investigation of up-sweep excitations with increasing rotational frequency confirmed that stochastic resonance is effective in optimizing the performance of the energy harvester, with a certain bandwidth of vehicle speeds. An actual-vehicle experiment validates that the prototype harvester using stochastic resonance is capable of improving power generation performance for practical tire application. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
A Novel Slope Method for Measurement of Fluid Density with a Micro-cantilever under Flexural and Torsional Vibrations
Sensors 2016, 16(9), 1471; https://doi.org/10.3390/s16091471
Received: 19 July 2016 / Revised: 7 September 2016 / Accepted: 8 September 2016 / Published: 11 September 2016
Cited by 3 | PDF Full-text (4382 KB) | HTML Full-text | XML Full-text
Abstract
A novel method, which was called a slope method, has been proposed to measure fluid density by the micro-cantilever sensing chip. The theoretical formulas of the slope method were discussed and established when the micro-cantilever sensing chip was under flexural and torsional vibrations. [...] Read more.
A novel method, which was called a slope method, has been proposed to measure fluid density by the micro-cantilever sensing chip. The theoretical formulas of the slope method were discussed and established when the micro-cantilever sensing chip was under flexural and torsional vibrations. The slope was calculated based on the fitted curve between the excitation and output voltages of sensing chip under the nonresonant status. This measuring method need not sweep frequency to find the accurate resonant frequency. Therefore, the fluid density was measured easily based on the calculated slope. In addition, the micro-cantilver was drived by double sided excitation and free end excitation to oscillate under flexural and torsional vibrations, respectively. The corresponding experiments were carried out to measure the fluid density by the slope method. The measurement results were also analyzed when the sensing chip was under flexural and torsional nonresonant vibrations separately. The measurement accuracies under these vibrations were all better than 1.5%, and the density measuring sensitivity under torsional nonresonant vibration was about two times higher than that under flexural nonresonant vibration. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
A Wideband Circularly Polarized Pixelated Dielectric Resonator Antenna
Sensors 2016, 16(9), 1349; https://doi.org/10.3390/s16091349
Received: 3 June 2016 / Revised: 15 August 2016 / Accepted: 18 August 2016 / Published: 23 August 2016
Cited by 5 | PDF Full-text (744 KB) | HTML Full-text | XML Full-text
Abstract
The design of a wideband circularly polarized pixelated dielectric resonator antenna using a real-coded genetic algorithm (GA) is presented for far-field wireless power transfer applications. The antenna consists of a dielectric resonator (DR) which is discretized into 8 × 8 grid DR bars. [...] Read more.
The design of a wideband circularly polarized pixelated dielectric resonator antenna using a real-coded genetic algorithm (GA) is presented for far-field wireless power transfer applications. The antenna consists of a dielectric resonator (DR) which is discretized into 8 × 8 grid DR bars. The real-coded GA is utilized to estimate the optimal heights of the 64 DR bars to realize circular polarization. The proposed antenna is excited by a narrow rectangular slot etched on the ground plane. A prototype of the proposed antenna is fabricated and tested. The measured −10 dB reflection and 3 dB axial ratio bandwidths are 32.32% (2.62–3.63 GHz) and 14.63% (2.85–3.30 GHz), respectively. A measured peak gain of 6.13 dBic is achieved at 3.2 GHz. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Helium Ion Microscope-Assisted Nanomachining of Resonant Nanostrings
Sensors 2016, 16(7), 1080; https://doi.org/10.3390/s16071080
Received: 2 May 2016 / Revised: 5 July 2016 / Accepted: 8 July 2016 / Published: 13 July 2016
PDF Full-text (2515 KB) | HTML Full-text | XML Full-text
Abstract
Helium ion microscopy has recently emerged as a potent tool for the in-situ modification and imaging of nanoscale devices. For example; finely focused helium ion beams have been used for the milling of pores in suspended structures. We here report the use of [...] Read more.
Helium ion microscopy has recently emerged as a potent tool for the in-situ modification and imaging of nanoscale devices. For example; finely focused helium ion beams have been used for the milling of pores in suspended structures. We here report the use of helium ion milling for the post-fabrication modification of nanostrings machined from an amorphous SiCN material. The modification consisted of milling linear arrays of holes along the length of nanostrings. This milling results in a slight decrease of resonant frequency while increasing the surface to volume ratio of the device. The frequency decrease is attributed to a reduction of the effective Young’s modulus of the string, which in turn reduces the tension the string is under. Such experimental observations are supported by the finite element analysis of milled and non-milled strings. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter
Sensors 2016, 16(7), 995; https://doi.org/10.3390/s16070995
Received: 29 April 2016 / Revised: 17 June 2016 / Accepted: 18 June 2016 / Published: 28 June 2016
Cited by 2 | PDF Full-text (4020 KB) | HTML Full-text | XML Full-text
Abstract
A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter [...] Read more.
A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10−11 hysteresis frequency difference. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
A MEMS Resonant Sensor to Measure Fluid Density and Viscosity under Flexural and Torsional Vibrating Modes
Sensors 2016, 16(6), 830; https://doi.org/10.3390/s16060830
Received: 11 March 2016 / Revised: 13 May 2016 / Accepted: 2 June 2016 / Published: 6 June 2016
Cited by 7 | PDF Full-text (5430 KB) | HTML Full-text | XML Full-text
Abstract
Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for [...] Read more.
Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS) technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m3 to 900 kg/m3 and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control
Sensors 2016, 16(6), 757; https://doi.org/10.3390/s16060757
Received: 16 March 2016 / Revised: 17 May 2016 / Accepted: 21 May 2016 / Published: 25 May 2016
PDF Full-text (2224 KB) | HTML Full-text | XML Full-text
Abstract
Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs) and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed [...] Read more.
Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs) and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution) with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current–voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
A Plasmonic Temperature-Sensing Structure Based on Dual Laterally Side-Coupled Hexagonal Cavities
Sensors 2016, 16(5), 706; https://doi.org/10.3390/s16050706
Received: 17 March 2016 / Revised: 28 April 2016 / Accepted: 4 May 2016 / Published: 17 May 2016
Cited by 10 | PDF Full-text (2574 KB) | HTML Full-text | XML Full-text
Abstract
A plasmonic temperature-sensing structure, based on a metal-insulator-metal (MIM) waveguide with dual side-coupled hexagonal cavities, is proposed and numerically investigated by using the finite-difference time-domain (FDTD) method in this paper. The numerical simulation results show that a resonance dip appears in the transmission [...] Read more.
A plasmonic temperature-sensing structure, based on a metal-insulator-metal (MIM) waveguide with dual side-coupled hexagonal cavities, is proposed and numerically investigated by using the finite-difference time-domain (FDTD) method in this paper. The numerical simulation results show that a resonance dip appears in the transmission spectrum. Moreover, the full width of half maximum (FWHM) of the resonance dip can be narrowed down, and the extinction ratio can reach a maximum value by tuning the coupling distance between the waveguide and two cavities. Based on a linear relationship between the resonance dip and environment temperature, the temperature-sensing characteristics are discussed. The temperature sensitivity is influenced by the side length and the coupling distance. Furthermore, for the first time, two concepts—optical spectrum interference (OSI) and misjudge rate (MR)—are introduced to study the temperature-sensing resolution based on spectral interrogation. This work has some significance in the design of nanoscale optical sensors with high temperature sensitivity and a high sensing resolution. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Fano Resonance Based on Metal-Insulator-Metal Waveguide-Coupled Double Rectangular Cavities for Plasmonic Nanosensors
Sensors 2016, 16(5), 642; https://doi.org/10.3390/s16050642
Received: 17 February 2016 / Revised: 19 April 2016 / Accepted: 29 April 2016 / Published: 5 May 2016
Cited by 24 | PDF Full-text (3755 KB) | HTML Full-text | XML Full-text
Abstract
A refractive index sensor based on metal-insulator-metal (MIM) waveguides coupled double rectangular cavities is proposed and investigated numerically using the finite element method (FEM). The transmission properties and refractive index sensitivity of various configurations of the sensor are systematically investigated. An asymmetric Fano [...] Read more.
A refractive index sensor based on metal-insulator-metal (MIM) waveguides coupled double rectangular cavities is proposed and investigated numerically using the finite element method (FEM). The transmission properties and refractive index sensitivity of various configurations of the sensor are systematically investigated. An asymmetric Fano resonance lineshape is observed in the transmission spectra of the sensor, which is induced by the interference between a broad resonance mode in one rectangular and a narrow one in the other. The effect of various structural parameters on the Fano resonance and the refractive index sensitivity of the system based on Fano resonance is investigated. The proposed plasmonic refractive index sensor shows a maximum sensitivity of 596 nm/RIU. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Prediction of the Strain Response of Poly-AlN/(100)Si Surface Acoustic Wave Resonator and Experimental Analysis
Sensors 2016, 16(5), 603; https://doi.org/10.3390/s16050603
Received: 2 March 2016 / Revised: 21 April 2016 / Accepted: 22 April 2016 / Published: 27 April 2016
Cited by 2 | PDF Full-text (4170 KB) | HTML Full-text | XML Full-text
Abstract
The strain sensitivity of the Aluminum Nitride (AlN)/Silicon (Si) surface acoustic wave resonator (SAWR) is predicted based on a modeling method introduced in this work, and further compared with experimental results. The strain influence on both the period of the inter-digital transducer (IDT) [...] Read more.
The strain sensitivity of the Aluminum Nitride (AlN)/Silicon (Si) surface acoustic wave resonator (SAWR) is predicted based on a modeling method introduced in this work, and further compared with experimental results. The strain influence on both the period of the inter-digital transducer (IDT) and the sound velocity is taken into consideration when modeling the strain response. From the modeling results, AlN and Si have opposite responses to strain; hence, for the AlN/Si-based SAWR, both a positive and a negative strain coefficient factor can be achieved by changing the thickness of the AlN layer, which is confirmed by strain response testing based on a silicon cantilever structure with two AlN configurations (1 μm and 3 μm in thickness, respectively). Full article
(This article belongs to the Special Issue Resonator Sensors)
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Open AccessArticle
Design and Verification of a Digital Controller for a 2-Piece Hemispherical Resonator Gyroscope
Sensors 2016, 16(4), 555; https://doi.org/10.3390/s16040555
Received: 16 February 2016 / Revised: 12 April 2016 / Accepted: 14 April 2016 / Published: 20 April 2016
Cited by 3 | PDF Full-text (5331 KB) | HTML Full-text | XML Full-text
Abstract
A Hemispherical Resonator Gyro (HRG) is the Coriolis Vibratory Gyro (CVG) that measures rotation angle or angular velocity using Coriolis force acting the vibrating mass. A HRG can be used as a rate gyro or integrating gyro without structural modification by simply changing [...] Read more.
A Hemispherical Resonator Gyro (HRG) is the Coriolis Vibratory Gyro (CVG) that measures rotation angle or angular velocity using Coriolis force acting the vibrating mass. A HRG can be used as a rate gyro or integrating gyro without structural modification by simply changing the control scheme. In this paper, differential control algorithms are designed for a 2-piece HRG. To design a precision controller, the electromechanical modelling and signal processing must be pre-performed accurately. Therefore, the equations of motion for the HRG resonator with switched harmonic excitations are derived with the Duhamel Integral method. Electromechanical modeling of the resonator, electric module and charge amplifier is performed by considering the mode shape of a thin hemispherical shell. Further, signal processing and control algorithms are designed. The multi-flexing scheme of sensing, driving cycles and x, y-axis switching cycles is appropriate for high precision and low maneuverability systems. The differential control scheme is easily capable of rejecting the common mode errors of x, y-axis signals and changing the rate integrating mode on basis of these studies. In the rate gyro mode the controller is composed of Phase-Locked Loop (PLL), amplitude, quadrature and rate control loop. All controllers are designed on basis of a digital PI controller. The signal processing and control algorithms are verified through Matlab/Simulink simulations. Finally, a FPGA and DSP board with these algorithms is verified through experiments. Full article
(This article belongs to the Special Issue Resonator Sensors)
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Review

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Open AccessReview
Recent Advances of MEMS Resonators for Lorentz Force Based Magnetic Field Sensors: Design, Applications and Challenges
Sensors 2016, 16(9), 1359; https://doi.org/10.3390/s16091359
Received: 23 May 2016 / Revised: 5 August 2016 / Accepted: 12 August 2016 / Published: 24 August 2016
Cited by 8 | PDF Full-text (12758 KB) | HTML Full-text | XML Full-text
Abstract
Microelectromechanical systems (MEMS) resonators have allowed the development of magnetic field sensors with potential applications such as biomedicine, automotive industry, navigation systems, space satellites, telecommunications and non-destructive testing. We present a review of recent magnetic field sensors based on MEMS resonators, which operate [...] Read more.
Microelectromechanical systems (MEMS) resonators have allowed the development of magnetic field sensors with potential applications such as biomedicine, automotive industry, navigation systems, space satellites, telecommunications and non-destructive testing. We present a review of recent magnetic field sensors based on MEMS resonators, which operate with Lorentz force. These sensors have a compact structure, wide measurement range, low energy consumption, high sensitivity and suitable performance. The design methodology, simulation tools, damping sources, sensing techniques and future applications of magnetic field sensors are discussed. The design process is fundamental in achieving correct selection of the operation principle, sensing technique, materials, fabrication process and readout systems of the sensors. In addition, the description of the main sensing systems and challenges of the MEMS sensors are discussed. To develop the best devices, researches of their mechanical reliability, vacuum packaging, design optimization and temperature compensation circuits are needed. Future applications will require multifunctional sensors for monitoring several physical parameters (e.g., magnetic field, acceleration, angular ratio, humidity, temperature and gases). Full article
(This article belongs to the Special Issue Resonator Sensors)
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