Uncooled IR imaging array based on quartz microresonators

A quartz crystal resonator's resonance frequency is sensitive to temperature. This sensitivity has been exploited in the past in thermometers made of single, macroscopic quartz resonators that can accurately detect temperature changes of μK. Using semiconductor microfabrication techniques, it is now possible to fabricate a large number of microresonators from a single quartz wafer. It is shown that combining the small thermal mass and high thermal isolation capability of such microresonators, the steep frequency versus temperature characteristics of resonators made of certain cuts of quartz and the low-noise characteristics of quartz crystal oscillators can result in high-performance infrared (IR) sensors and sensor arrays. In a microresonator sensor, the temperature change produced by the absorption of IR energy results in a frequency change that can be measured with a resolution that corresponds to a change in the resonator's temperature of less than a μK. Calculation shows that an array of microresonators in the 200 MHz-1 GHz range can be the basis of an uncooled IR imaging system with a noise equivalent temperature difference, NETD, of <0.01 K. The design and fabrication problems to be overcome before such microresonator arrays can be realized are discussed     

The quartz crystal microbalance: mass sensitivity, viscoelasticity and acoustic amplification

Quartz crystal resonators (QCR) respond to surface mass and material properties of a film coated on their surface. The acoustic load acting at the surface of the resonator is a more general parameter to describe this dependence. It can be represented by a mass factor and an acoustic factor. The quotient of resistance increase and frequency shift can be used for the determination of the acoustic factor, if the loss tangent of the coating is known. Viscoelastic properties of sensitive coatings can enhance the mass sensitivity of quartz crystal microbalance (QCM) sensors. Acoustic factor and acoustic amplification effective during chemical sensing are not the same.

We further suggest a sensor concept, which is based on a bilayer arrangement. Acoustic amplification with a viscoelastic film and chemical sensitivity is separated. With a proper selection of materials, the first layer realizes acoustic amplification while the (chemical) sensitive layer acts as a pure mass detector. Major sensor design parameters are the shear modulus and the thickness of the first layer; major challenge is the preparation of a homogeneous and uniform first film.     

双通道压电式密度传感器的研究

在同一压电石英晶片上制备两个石英晶体谐振器 ,实验结果表明双通道之间的相互干扰可以忽略。在石英晶体表面修饰多孔TiO2 膜层 ,可大大提高传感器对液体密度的灵敏度。采用两个修饰不同厚度TiO2 膜层的双通道压电传感器的频率差作为测量信号 ,可以消除液体粘度的影响 ,并获得与液体密度有良好线性关系的工作曲线 ,实现液体密度的测定     

精密石英谐振式位移传感器

提出了用石英晶体谐振器构成的超精密位移或压力传感器的原理．由于石英晶体振荡器有超常的精度和稳定性，因而组成的位移或压力传感器也具有极高的精度和线性。还引入双晶振的差频原理，既消除了温度影响，又提高了频率变化范围，提高了测量分辨率。     

High-precision low-power quartz tuning fork temperature sensor with optimized resonance excitation

This paper presents the design, fabrication, and characterization of a quartz tuning fork temperature sensor based on a new ZY-cut quartz crystal bulk acoustic wave resonator vibrating in a flexural mode. Design and performance analysis of the quartz tuning fork temperature sensor were conducted and the thermal sensing characteristics were examined by measuring the resonance frequency shift of this sensor caused by an external temperature. Finite element method is used to analyze the vibratory modes and optimize the structure of the sensor. The sensor prototype was successfully fabricated and calibrated in operation from 0 to 100 °C with the thermo-sensitivity of 70×10^?6/°C. Experimental results show that the sensor has high thermo-sensitivity, good stability, and good reproducibility. This work presents a high-precision low-power temperature sensor using the comprehensive thermal characterization of the ZY-cut quartz tuning fork resonator.     

压电谐振力传感器零位不稳定性的机理和试验

介绍了一种研究石英谐振器力频特性的新方法,利用此方法对平面型和透镜型石英谐振器进行了对比分析,并结合这2种谐振器性能的对比分析试验,得出石英谐振器的电极质量敏感性是引起谐振器零位不稳定和频率短期不稳定的一个主要原因,理论和试验一致表明:通过改善石英谐振器的形状可使这种不稳定性降到原来的1%。     

Micromachined Acoustic Resonant Mass Sensor

This paper describes a highly sensitive, film bulk acoustic resonator (FBAR) mass sensor (built on a micromachined silicon-nitride diaphragm with a piezoelectric thin film and Al electrodes) that can operate in vapor and liquid. The sensitivity of the device to mass change on its surface has been investigated by having various thicknesses of silicon-nitride support layer and also of Al layer. The sensor is measured to have a mass sensitivity of 726 cm$^2$/g, which is about 50 times that of a typical quartz crystal microbalance (QCM). In vapor, the sensor (operating at around 1 GHz and having a relatively high quality (Q) factor of 200–300) shows a minimum detectable frequency shift of about 400 Hz, which corresponds to a mass change of$10^-9$g/cm$^2$on the sensor surface, comparable with that detectable by a QCM. In liquid, though the Q usually drops more than an order of magnitude, we obtain a Q of 40 at 2 GHz by using a second harmonic resonance of the resonator. And with the Q, a minimum 5 ppm resonant frequency shift can be detected, which corresponds to$10^- 8$g/cm$^2$change on the sensor surface.hfillhbox[1374]     

Highly sensitive mass sensor using film bulk acoustic resonator

Film bulk acoustic resonators (FBAR) have recently been adopted as alternatives to surface acoustic wave (SAW) in high frequency devices, due to their inherent advantages, such as low insertion loss, high power handling capability and small size. FBAR device can also be one of the standard components as mass sensor applications. FBAR sensors have high sensitivity, good linearity, low hysteresis and wide adaptability. In this study, a highly sensitive mass sensor using film bulk acoustic resonator was developed. The device structure of FBAR is simulated and designed by the Mason model, and fabricated using micro electromechanical systems (MEMS) processes. The fabricated FBAR sensor exhibits a resonant frequency of 2442.188 MHz, measured using an HP8720 network analyzer and a CASCADE probe station. Experimental results indicate that the mass loading effects agree with the simulated ones. Results of this study demonstrate that the sensitivity of the device can be achieved as high as 3654 Hz cm²/ng.     

Dew point and relative humidity measurement using a quartz resonant sensor

A new dew point measurement device for humidity measurement in high temperature environment using a quartz crystal sensor was proposed. Combined with Peltier module and quartz crystal, active condensation occurs in the quartz surface to change the mass on the surface of quartz crystal, and use the shift of its resonant frequency identify the time of condensation. This quartz sensor does not require any absorbent material, and it is directly stuck on the Peltier element. The sensor system can also be achieved relative humidity measurement based on dew point and ambient-temperature measuring. It can operate in the range of dew point temperature from 50 to ?30 °C, and in the range of relative humidity from 1 to 90 % RH. The measured dew points values and relative humidity values showed very good agreement with reference values and were within ±0.3 °C, 1 % RH, respectively over the whole temperature range.     

Modeling of the intrinsic stress effect on the resonant frequency of NEMS resonators integrated by beams with variable cross-section

Nano-electro-mechanical systems (NEMS) resonators integrated by a double clamped beam with variable cross-section are used in several applications such as chemical and biological detectors, high-frequency filters, and signal processing. The structure of these resonators can experience intrinsic stresses produced during their fabrication process. We present an analytical model to estimate the first bending resonant frequency of NEMS resonators based on a double clamped beam with three cross-sections, which considers the intrinsic stress effect on the resonant structure. This model is obtained using the Rayleigh and Macaulay methods, as well as the Euler–Bernoulli beam theory. We applied the analytical model to a silicon carbide (SiC) resonator of 186 nm thickness reported in the literature. This resonator has a total length ranking from 80 to 258 μm and is subjected to a tensile intrinsic stress close to 110 MPa. Results from this model show good agreement with experimental results. The analytic frequencies have a maximum relative difference less than 6.3% respect to the measured frequencies. The tensile intrinsic stress on the resonant structure causes a significantly increase on its bending resonant frequency. The proposed model provides an insight into the study of the intrinsic stress influence on the resonant frequency of this nanostructure. In addition, this model can estimate the frequency shift due to the variations of the resonator geometrical parameters.     

一种新型智能机器人敏感皮肤的触觉传感器阵列

本文提出了一种眼精密，高位置分辩率，快速响应的，可任意分布的，便于大规模集成的智能化机器人的多参量融合的的阵列触觉传感器，介绍了石英晶振精密分布测量压力，形变，温度，生物量和化学量的原理。该系统传感及信号传输方法独特，精度，分辩率和响应速度等指标优于其他机器人敏感皮肤系统。     

Generation and swapping of multi-qubit entangled state in a coupled superconducting resonator array

An efficient method is proposed for the generation and swapping of multi-qubit entangled state in an array of linearly coupled superconducting resonators, each of which is coupled to N superconducting qubits. With the external driving fields to adjust the desired qubit–resonator interaction, we firstly show that the multipartite entangled state of superconducting qubits hosted in two nearest-neighbor interacting resonators can be deterministically realized. Furthermore, by utilizing the produced entangled state, we put forward a protocol for the swapping of quantum entangled state in the coupled resonator array based on measurement, i.e., the multi-particle entangled state can be achieved for the qubits in long-distance separated resonators. The numerical simulation suggests that our scheme is feasible with current circuit QED technology.     

A novel dual‐band bandpass filter using co‐directional split ring resonators with closely spaced passbands and wide upper stopband

In this article, interdigital capacitor loaded co‐directional split ring resonators (CDSRRs) and their dual‐band bandpass filter applications are proposed. The proposed resonator is formed by nested open loop resonators having open ends at the same place unlike conventional split ring resonators (SRRs). In addition, the inner open loop resonator has interdigital capacitor located between the open ends. The proposed resonator exhibits dual resonance behavior with a small center frequency ratio. Both of resonance frequencies can be controlled due to the changes in the interdigital capacitor and the electrical length of the outer resonator. A dual‐band microstrip bandpass filter is designed by using the proposed CDSRR. Two CDSRRs are used to obtain two poles in each passband. Overall electrical length of the designed filter is 0.23 λ_g × 0.14 λ_g (0.0329 λ_g²), where λ_g is the guided wavelength for the used substrate at the lowest passband center frequency of 1.8 GHz. A small center frequency is obtained by adjusting the second passband at 2.27 GHz. A very wide upper stopband, closely spaced passbands, low insertion losses and high selectivity at both passbands can be obtained by means of the proposed structure. The designed filter was also fabricated and tested. The measured results show a very good agreement with the predicted results.     

基于PQCR-PSL的桥梁振动无线监测系统

基于压电式石英晶体谐振器与平面螺旋电感串联结构(PQCR-PSL),结合现场可编程门阵列(FPGA)、无线传感器网络(WSNs)和C#等技术,将一种结构简单、以频率为输出的数字化石英晶体电感传感器应用到桥梁振动等低频测量中,并以此为传感器探头搭建了整套无线监测系统.系统主要由传感器探头、FPGA系统、ZigBee网络、C#位机4部分组成,具有结构简单、稳定性好、数字化输出等特点,实现了对低频振动信号的非接触式无线实时监测.     

Thermal Isolation of Encapsulated MEMS Resonators

This paper presents an in-chip thermal-isolation technique for a micro-ovenized microelectromechanical-system resonator. Resonators with a microoven can be used for high-precision feedback control of temperature to compensate for the temperature dependence of resonator frequency over a wide temperature range. However, ovenization requires power consumption for heating, and the thermal time constant must be minimized for effective temperature control. This paper demonstrates an efficient local-thermal-isolation mechanism, which can reduce the power requirement to a few milliwatts and the thermal time constant to a few milliseconds. In this method, the mechanical suspension of the resonator is modified to provide thermal isolation and include an integrated resistive heater. This combination provides mechanical suspension, electrical heating, and thermal isolation in a compact structure that requires low heating power and has a small thermal time constant. A power consumption of approximately 12 mW for a 125degC temperature rise and a thermal time constant ranging from 7 to 10 ms is reported in this paper, which is orders of magnitude lower than that of commercially available ovenized quartz resonators. A CMOS-compatible wafer-scale encapsulation process is used to fabricate this device, and the thermal-isolation design is achieved without any modification to the existing resonator fabrication process.     

A Micromachined Quartz Resonator Array for Biosensing Applications

An 8-pixel micromachined quartz crystal resonator array with a fundamental resonance frequency of 66 MHz has been designed, fabricated, and tested. A compact impedance-spectrum-analyzer electronic interface has been developed and combined with the quartz resonator array to form the biosensing system. The sensor array was calibrated using water–glycerol solutions, and the performance was found to be exactly as expected. Measurement of the crosstalk between the sensor pixels showed an isolation of $sim$ 30 dB. Selective functionalization of the pixels was achieved through the use of aqueous 3, 3 $^{prime}$-Dithiobis (sulfosuccinimidylpropionate) (DTSSP) molecules. The adsorption of avidin on DTSSP gave a frequency signal of 60 kHz in comparison to unfunctionalized pixels. The specific adsorption of avidin on functionalized pixels was confirmed through fluorescence microscopy. Comparing the performance of the micromachined quartz crystal microbalance (QCM) with a commercial 5-MHz device, we found that the micromachined QCM has a 4.25 times higher signal-to-noise ratio. Based on the measurement of the noise and using three times the frequency noise as the limit for the detection of avidin molecules, we expect to resolve a minimum of $sim$1/960 of a monolayer of avidin corresponding to an aerial mass density resolution of 0.7 $hbox{ng/cm}^{2}$ .$hfill$[2008-0196]      

Comparison of FBAR and QCM-D sensitivity dependence on adlayer thickness and viscosity

Unlike the quartz crystal microbalance, which has been used extensively for the analysis of biochemical interactions, only few measurements with biochemical adsorbent have been done with film bulk acoustic resonators (FBAR). In this paper, the FBAR behaviour on exposure to a lipid vesicle solution and the formation of a polyelectrolyte multilayer structure is investigated and compared with the results obtained with the quartz crystal microbalance. Differences in the resonator response were found between the two techniques and depending on the resonators resonance frequency ranging from the MHz to the GHz regime. As an explanation, we suggest that the penetration depth and the influence on viscoelastic properties, which are both known to be frequency dependent, cause the variations in the results. As a consequence, the higher operating resonance frequencies of the FBAR increase the sensitivity to changes in the viscoelasticity of the adsorbent and also decrease the sensing length of the device.     

单片式压电谐振型石英压力-温度传感器设计

提出了一种采用石英力敏谐振器(QFSR)-石英热敏谐振器(QTSR)的单片式压电谐振型石英压力-温度传感器(QPTS),设计了单片式QPTS结构、石英压力传感器的无应力封接方案以及新型压力-伸缩力变换器.单片式QPTS由QFSR和QTSR构成,均采用AT切型,厚度切变模式工作,不同的是QTSR的长边取向与石英X轴的夹角为60°.无应力封接方案使用石英、单晶硅、非晶态SiC、硼硅酸盐玻璃和柯伐合金的组合,并且利用石英化学刻蚀和物理修饰技术以及半导体的新工艺使QFSR和QTSR改性.其中,非晶态SiC层的制作是为了实现应力的缓冲:虽然硅和石英材料的热膨胀系数不匹配,可是二者之间的非晶态SiC层却能够良好地吸收其热应力,成为无应力结构.     

A widely tunable bandpass filter adopting novel fully tunable resonators

A widely tunable bandpass filter adopting a novel fully tunable resonator is proposed in this letter. The fully tunable resonator is mainly consisted of an open ring, a frequency tuning structure, and a coupling tuning structure. Adopting the fully resonators, the center frequency, the input/output external Q value, and the coupling coefficients can be tuned at the same time. And the tuning range of a tunable filter adopting the novel fully tunable resonators can be expanded. The fully tunable resonators can be combined to achieve more excellent suppression performance. A widely tunable bandpass filter consisted of five fully tunable resonators with 86.5% frequency tuning range is designed, fabricated, and measured. The simulated results are in good agreement with the measured ones.     

A compact tri‐band microwave resonator for ethanol gas detection

This article presents the design, simulation, fabrication, and testing of a compact two‐port microwave resonator coated with nanomaterials for ethanol gas sensing applications. The proposed gas sensor consists of a transmission line loaded with three triangular split ring resonators for ethanol detection at three frequency bands viz. 2.2, 4.6, and 6.3 GHz. The transmission line has all‐pass characteristics in which band gaps are introduced using three split ring resonators. The TiO₂ and ZnO nanorods are used as sensitive layers for the proposed sensing application. The nanorods, which are grown on a glass substrate of thickness 1 mm, are loaded on to the two‐port microwave resonator making the device sensitive to ethanol. The microwave behavior of the sensor is analyzed using the scattering parameters. The absorption of the ethanol gas causes frequency detuning which is used to analyze the presence of ethanol and its concentration. From the experiments, it is understood that there is an increase in the frequency shift with an increase in the concentration of ethanol gas. The sensing device with ZnO as a sensitive layer showed a higher average sensitivity of 2.35 compared to TiO₂ whose average sensitivity is 1.29.