Quartz Crystal Resonator Research Articles

Frequency Shift of a Quartz Crystal Resonator Carrying an Array of Nano-Beams

Frequency Shift of a Quartz Crystal Resonator Carrying an Array of Nano-Beams

Application of Ultra-sensitive Pillar-enhanced Quartz Crystal Resonators for Airborne Detection of Nanoparticles: A Theoretical Study

Application of Ultra-sensitive Pillar-enhanced Quartz Crystal Resonators for Airborne Detection of Nanoparticles: A Theoretical Study

Investigating Hydrodynamic Loading Effects on Resonant Frequency Shift of Quartz Crystal Resonator with Attached Particles

Investigating Hydrodynamic Loading Effects on Resonant Frequency Shift of Quartz Crystal Resonator with Attached Particles

Temperature characteristics of a thickness shear mode quartz crystal resonator bonded to a support substrate

Thickness shear mode (TSM) resonators consisting of metal films and quartz plates are widely used for sensor applications such as film thickness monitoring, force sensors, and odor sensors. However, the current sensor geometry prevents further improvements in its sensitivity and stability. Thinning the plate is necessary for high sensitivity, and advanced fabrication technologies are required for their commercialization. The solution is to use a support substrate to increase the mechanical strength, which can guide the transmittance of the electric field. Herein, we report a TSM resonator bonded to a support substrate. An AT-cut quartz resonator with a floating electrode on the top side was bonded to the support substrate. Two excitation electrodes were placed under the substrate. The support substrates evaluated in this study included borosilicate glass, Z-cut quartz crystals, and AT-cut quartz crystal plates. The quartz crystal resonator (QCR) bonded to the AT-cut quartz crystal plate and positioned at 90° to the crystallographic x-axis shows an excellent temperature coefficient of frequency of −60 ± 14 ppb/°C for a temperature range 11–40 °C. The proposed method reduces temperature sensitivity to 1/4 or less compared to that without a substrate. Furthermore, the resonator could be used as a quartz crystal microbalance. The proposed method may inspire further high-frequency QCR-based biochemical chips or various sensor applications with TSM resonators.

Portable Quartz Crystal Resonator Sensor for Characterising the Gelation Kinetics and Viscoelastic Properties of Hydrogels

Hydrogel biomaterials have found use in various biomedical applications partly due to their biocompatibility and tuneable viscoelastic properties. The ideal rheological properties of hydrogels depend highly on the application and should be considered early in the design process. Rheometry is the most common method to study the viscoelastic properties of hydrogels. However, rheometers occupy much space and are costly instruments. On the other hand, quartz crystal resonators (QCRs) are devices that can be used as low-cost, small, and accurate sensors to measure the viscoelastic properties of fluids. For this reason, we explore the capabilities of a low-cost and compact QCR sensor to sense and characterise the gelation process of hydrogels while using a low sample amount and by sensing two different crosslink reactions: covalent bonds and divalent ions. The gelation of covalently crosslinked mucin hydrogels and physically crosslinked alginate hydrogels could be monitored using the sensor, clearly distinguishing the effect of several parameters affecting the viscoelastic properties of hydrogels, including crosslinking chemistry, polymer concentrations, and crosslinker concentrations. QCR sensors offer an economical and portable alternative method to characterise changes in a hydrogel material's viscous properties to contribute to this type of material design, thus providing a novel approach.

Feature-Weighted Echo State Network for Dynamic Frequency Offset Modeling of Quartz Crystal Resonators.

Quartz crystal resonators are widely used as reference frequency sources in modern electronic systems. However, their frequency often deviates from the nominal value due to the significant change in the ambient temperature. Therefore, it is of great value to develop an accurate dynamic frequency offset model regarding temperature changes. In this article, a novel feature-weighted echo state network (FWESN) method is presented to capture the dynamic frequency-temperature ( f - T ) characteristic of quartz crystal resonators. Different from the traditional echo state network (ESN), which simply takes the temperature measurement signal as a single model input variable, the proposed method mines the feature information hidden in the temperature measurement series to construct the model input vector. Specifically, five dynamic features are designed to substitute for the original temperature signal by investigating the influence mechanism of temperature versus frequency. Furthermore, considering the difference in these features' importance, two feature weighting strategies, including the Pearson's correlation coefficient (PCC)-based and particle swarm optimization (PSO)-based, are proposed to assign the different weights to the five features. Finally, the weighted features are fed into the ESN model to implement the dynamic frequency offset estimation. The application results on the real experiment datasets demonstrate that the presented FWESN method can estimate the frequency offset more precisely than the basic ESN method.

Bacteriophage-Based Biosensors: A Platform for Detection of Foodborne Bacterial Pathogens from Food and Environment.

Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity and a prolonged time-to-result. The specificity and sensitivity of assays for live pathogen detection may also depend on the nature of the samples being analyzed and the immunological or molecular reagents used. Bacteriophage-based biosensors offer several benefits, including specificity to their host organism, the detection of only live pathogens, and resistance to extreme environmental factors such as organic solvents, high temperatures, and a wide pH range. Phage-based biosensors are receiving increasing attention owing to their high degree of accuracy, specificity, and reduced assay times. These characteristics, coupled with their abundant supply, make phages a novel bio-recognition molecule in assay development, including biosensors for the detection of foodborne bacterial pathogens to ensure food safety. This review provides comprehensive information about the different types of phage-based biosensor platforms, such as magnetoelastic sensors, quartz crystal microbalance, and electrochemical and surface plasmon resonance for the detection of several foodborne bacterial pathogens from various representative food matrices and environmental samples.

Wet Etching of Quartz Using a Solution Based on Organic Solvents and Anhydrous Hydrofluoric Acid.

The quartz-crystal resonator is the core device for frequency control in modern communication systems and network technology. At present, in modern resonator blanks manufacturing, BOE solution is usually used as the etching solution, but its etching rate is relatively volatile, and the surface morphology of the blanks is prone to defects after etching, which brings certain difficulties to the deep-etching process of the wafer. To solve the above challenges, this paper systematically compares a BOE solution and anhydrous etching solution in terms of etching rate, surface morphology, and electrical properties of the blanks after etching. Seven groups of blanks were etched using different etching solutions with different etching conditions to verify their effect on the surface morphology and electrical properties of quartz blanks. The experimental results suggest that the application of anhydrous etching solution has achieved better surface morphology and electrical properties and can be more suitable for application in batch manufacturing. In general, when using anhydrous etching solution, it is possible to reduce surface roughness by up to 70% and equivalent resistance by 32%, and the etch rate is almost 10 times lower than BOE solution under the same temperature, which is more conducive to the rate control of wafers in the etching process.

Research on Dual-Technology Fusion Biosensor Chip Based on RNA Virus Medical Detection.

In recent years, the emergence of COVID-19 and other epidemics caused by RNA(ribonucleic acid)-type genetic viruses has aroused the close attention of governments around the world on emergency response to public safety and health emergencies. In this paper, an electrodeless biosensing detection chip for RNA virus medical detection is designed using quartz crystal microbalance technology and local surface plasmon resonance technology. The plasmonic resonance characteristic in the nanostructures of gold nanorods-quartz substrates with different parameters and the surface potential distribution of the quartz crystal microbalance sensing chip were studied by COMSOL finite element simulation software. The results show that the arrangement structure and spacing of gold nanorod dimers greatly affect the local surface plasmon resonance of nanorods, which in turn affects the detection results of biomolecules. Moreover, high concentrations of “hot spots” are distributed between both ends and the gap of the gold nanorod dimer, which reflects the strong hybridization of the multiple resonance modes of the nanoparticles. In addition, by simulating and calculating the surface potential distribution of the electrode area and non-electrode area of the biosensor chip, it was found that the biosensor chip with these two areas can enhance the piezoelectric effect of the quartz chip. Under the same simulation conditions, the biochip with a completely electrodeless structure showed a better sensing performance. The sensor chip combining QCM and LSPR can reduce the influence of the metal electrode on the quartz wafer to improve the sensitivity and accuracy of detection. Considering the significant influence of the gold nanorod dimer plasma resonance mode and the significant advantages of the electrodeless biosensor chip, an electrodeless biosensor combining these two technologies is proposed for RNA virus detection and screening, which has potential applications in biomolecular measurement and other related fields.

An Analysis of the Thermal Behavior and Effects of Circular Quartz Crystal Resonators for Microbalance Applications.

The accurate calculation of vibration frequency is essential in design of circular quartz crystal resonators which are the core elements of high-precision microbalances used for testing and measurement. Currently, the prediction of thermal effects on frequency through an analytical analysis is still in its developmental stage, mainly due to the complexity of solving the 3-D equations with the consideration of asymmetric structure of resonators and electrodes along with material anisotropy. By using a scalar differential equation for vibrations with the eigen-displacement of thickness mode, the eigen-frequency of a plano-convex AT-cut circular quartz crystal plate with asymmetric electrodes is determined. Furthermore, the temperature effect in the scalar differential equation is successfully obtained by incorporating the incremental thermal field theory into the 1-D analysis. The theoretical results agree well with the experimental data. The combination of the thermal field and the thickness model for circular quartz crystal resonators can realize a full analysis of thermal properties in vital applications such as high-sensitivity microbalance sensors.

A force measurement platform for a vitreoretinal surgical simulator using an artificial eye module integrated with a quartz crystal resonator

To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane (ILM) peeling, we developed an artificial eye module comprising a quartz crystal resonator (QCR) force sensor and a strain body that serves as a uniform force transmitter beneath a retinal model. Although a sufficiently large initial force must be loaded onto the QCR force sensor assembly to achieve stable contact with the strain body, the highly sensitive and wide dynamic-range property of this sensor enables the eye module to detect the slight forceps contact force. A parallel-plate strain body is used to achieve a uniform force sensitivity over the 4-mm-diameter ILM peeling region. Combining these two components allowed for a measurable force range of 0.22 mN to 29.6 N with a sensitivity error within −11.3 to 4.2% over the ILM peeling area. Using this eye module, we measured the applied force during a simulation involving artificial ILM peeling by an untrained individual and compensated for the long-term drift of the obtained force data using a newly developed algorithm. The compensated force data clearly captured the characteristics of several types of motion sequences observed from video recordings of the eye bottom using an ophthalmological microscope. As a result, we succeeded in extracting feature values that can be potentially related to trainee skill level, such as the mean and standard deviation of the pushing and peeling forces, corresponding, in the case of an untrained operator, to 122.6 ± 95.2 and 20.4 ± 13.2 mN, respectively.

Stiffness Measurement of Organoids Using a Wide-Range Force Sensor Probe Fabricated Using a Quartz Crystal Resonator

The automation of the experimental process and evaluation method is required to screen chemical substances in the fields of biology and chemistry. In the case with biological evaluations, the automation of the mechanical probing has been considered, but the measurement method should possess versatility as the mechanical properties of biological samples widely distribute. We present a stiffness measurement using a quartz crystal resonator (QCR) fabricated force sensor probe. Owing to the low frequency noise, the QCR force sensor exhibits a wide force measurement range. We measured the stiffness of the two samples, organoids and polydimethylsiloxane (PDMS) beads, that have different Young’s modulus. The fabricated QCR sensor probe exhibited the measurement range over five digits with the force resolution of 272 nN and the maximum load of over 30 mN. Using the sensor probe, the stiffness of organoids and PDMS beads was successfully evaluated; 2.51 kPa and 1.19 MPa, respectively. As a result, we succeeded in measuring the stiffness of various samples whose Young’s modulus distributed over three digits.

Non-contact bolt axial force measurement based on the deformation of bolt head using quartz crystal resonator and coils

As a health monitoring tool of bolts in infrastructures, we propose a non-contact evaluation method for the axial force of a bolt. Deformation of the bolt head is measured as an electrical capacitance variation detected as a frequency shift of a simple circuit composed of a quartz crystal resonator and coils. The measurement was carried out via magnetic field coupling between the coil installed on the bolt head and another coil connected to the measurement instrument. Since the method requires no active electronic circuit or battery for the bolt, low cost and high durability can be expected. First, the circuit was analyzed and optimized using an equivalent circuit model. Then, the feasibility of the proposed method was experimentally studied using a prototype. It was demonstrated that the method enabled non-contact axial force estimation in which the dependence on the distance between the coils is sufficiently small for detecting bolt looseness.

Simpler and faster quartz crystal microbalance for macromolecule detection using fixed frequency drive

Despite advancements in analytical technologies, their complexity and cost have largely restricted their application in scalable online or multiplexed measurements. Here we report a quartz crystal resonator (QCR)-based method for detection of macromolecules that allows immensely simpler and faster measurements by employing for the first time a fixed frequency drive (FFD) and analytical expressions of acoustic parameters. Using human immunoglobulin E (hIgE) as an exemplar macromolecule and an anti-hIgE aptamer functionalised on a QCR, quantitative accuracy was benchmarked against the traditional impedance analysis method. The ability of FFD to capture data over longer observation periods at significantly higher acquisition rates at a fixed amplitude showed improvement in the QCR’s sensitivity and specificity of transduction. The foundations for low-cost and low-power online integration and large-scale multiplexability are also discussed.

Dynamic Frequency-Temperature Characteristic Modeling for Quartz Crystal Resonator Based on Improved Echo State Network.

Quartz crystal resonators are the key component of various kinds of electronic systems because they provide the reference frequency source of the system running clocks. However, the frequency stability is often affected by the temperature. Therefore, the frequency-temperature ( f-T ) characteristic modeling has been an important research topic in the frequency control field. The classic f-T modeling method omits the system dynamics and may lead to a large frequency compensation error in the case of rapid temperature changing. To deal with this issue, this article proposes a dynamic f-T modeling method based on improved echo state network (ESN), called residual scaled ESN (RSESN). In the proposed method, the residual modeling framework is designed for purposes of good physical understandability and high prediction precision. This framework uses the static polynomial f-T model to depict the approximated data relationship and applies the complicated network model to compensate the detailed dynamic error. To estimate the dynamic errors, one effective dynamic modeling tool, ESN, is introduced to build the dynamic compensation model for f-T characteristic of quartz crystal resonators. For a better fitting performance, the ESN activation limitations are analyzed and the scaled echo states are constructed in the improved ESN model. The modeling and testing results on the real experiment data show that the proposed method can capture the dynamic information effectively and provide better frequency deviation predictions.

Final report on key comparison APMP.M.P-K7.3 in hydraulic gauge pressure from 10 MPa to 100 MPa

Main textThis report describes the results of a key comparison among hydraulic high pressure standards that have been maintained by seven National Metrology Institutes (NMIs: NIMT, NMIJ/AIST, NPLI, RCM-LIPI, NMIM, VMI and NMLPHIL). This comparison was carried out during the period March 2016 to October 2017 within the framework of the Asia-Pacific Metrology Programme (APMP) in order to determine their degrees of equivalence in the pressure range from 10 MPa to 100 MPa, gauge mode. The pilot institute was the National Institute of Metrology (Thailand) (NIMT). All participating institutes used hydraulic pressure balance as their pressure standards. In order to ensure reliability, two high precision pressure transducers were used as the transfer standard. The sensing element of the transducers was a precision quartz crystal resonator attached to a small Bourdon tube. During the comparison, the transfer standard was calibrated at the pilot institute two times, before and after circulating the transfer standard to participants. From the two NIMT calibration results, the transfer standard was sufficiently stable to meet the requirements of the comparison. The long-term instability obtained from the two calibration results was taken into account as the uncertainty of the transfer standard for all participants. As the matter of fact NPL India and NMIM participated in this comparison as one of the linkage institutes and participating institutes, respectively. However, it was found later that the systems of hydraulic pressure balance reference standards used in this comparison were not functioning. Therefore, the comparison results were withdrawn. The degrees of equivalence of each national measurement standard were expressed quantitatively by deviations from the key comparison reference value of the corresponding CCM key comparison, CCM.P-K7 through the linkage institute, NMIJ/AIST. In conclusion, the hydraulic pressure standards in the range 10 MPa to 100 MPa, gauge mode of the five participating NMIs were found to be equivalent within their claimed uncertainties.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Physicochemical and statistical characterization of gas-sensing behaviors of resonator sensors with carbonaceous films prepared by rf-sputtering of aromatic and hydrophilic biomolecules

Quartz crystal resonators coated with gas-sorptive films were characterized by analyzing their structures and their organic gas-sorption behaviors, which were then studied using statistics and computational molecular simulations. The films had carbonaceous structures that were prepared by radio-frequency (rf) sputtering of aromatic biomolecules, such as cytosine and lignin. These films had been compared with the rf-sputtered films of hydrophilic biopolymer of lignin and gelatin.The composition and morphology of each film governed the organic gas-sorption characteristics of the resonator sensors used for organic gas-sensing. The cytosine film, which was nitrogen-rich and layered, had a moderate affinity for the larger molecules of normal alcohols and acetate esters. The cytosine film is repulsive to positively-charged moieties of adsorbates. In contrast, the agarose film, which was nitrogen-poor and columnar, had a high affinity for small adsorbates with short hydrocarbon chains. Molecular flexibility of the adsorbate played an important role in the gas-sorption ability of the agarose film. Molecular dynamics simulation clarified that the weakly dipolar adsorbate-aggregate were immiscible in the cytosine adsorbent-aggregate because the collision mixture was prone to be instable. In practice, the cytosine-sputtered film had a higher gas-sorption ability for weakly dipolar species that have the longer hydrocarbon chains.

Streptavidin Coverage on Biotinylated Surfaces.

Biosensors and other biological platform technologies require the functionalization of their surface with receptors to enhance affinity and selectivity. Control over the functionalization density is required to tune the platform’s properties. Streptavidin (SAv) monolayers are widely used to immobilize biotinylated proteins, receptors, and DNA. The SAv density on a surface can be varied easily, but the predictability is dependent on the method by which the SAv is immobilized. In this study we show a method to quantitatively predict the SAv coverage on biotinylated surfaces. The method is validated by measuring the SAv coverage on supported lipid bilayers with a range of biotin contents and two different main phase lipids and by using quartz crystal microbalance and localized surface plasmon resonance. We explore a predictive model of the biotin-dependent SAv coverage without any fit parameters. Model and data allow to predict the SAv coverage based on the biotin coverage, in both the low- and high-density regimes. This is of special importance in applications with multivalent binding where control over surface receptor density is required, but a direct measurement is not possible.

Development of quartz crystal complex capacitive sensor with microelectrode array for sensitization

AbstractIn this paper, we report a development of quartz crystal complex capacitive sensor with microelectrode array for local detection of liquid sample. This sensor is composed of the sensing capacitor (SC) with microelectrode array and quartz crystal resonator (QCR). It is a contactless capacitive sensor using out‐of‐plane electric field of a planer SC. We succeeded in confining the electric field by placing microelectrode array on the SC and improving the spatial resolution of the sensor. This sensor enables local capacitive detection of target materials. This sensor is expected to be applied to the detection system of μ‐TAS.

Phenolic Resin Dual-Use Stamps for Capillary Stamping and Decal Transfer Printing.

We report an optimized two-step thermopolymerization process carried out in contact with micropatterned molds that yields porous phenolic resin dual-use stamps with topographically micropatterned contact surfaces. With these stamps, two different parallel additive substrate manufacturing methods can be executed: capillary stamping and decal transfer microlithography. Under moderate contact pressures, the porous phenolic resin stamps are used for nondestructive ink transfer to substrates by capillary stamping. Continuous ink supply through the pore systems to the contact surfaces of the porous phenolic resin stamps enables multiple successive stamp-substrate contacts for lithographic ink deposition under ambient conditions. No deterioration of the quality of the deposited pattern occurs, and no interruptions for ink replenishment are required. Under a high contact pressure, porous phenolic resin stamps are used for decal transfer printing. In this way, the tips of the stamps' contact elements are lithographically transferred to counterpart substrates. The granular nature of the phenolic resin facilitates the rupture of the contact elements upon stamp retraction. The deposited phenolic resin micropatterns characterized by abundance of exposed hydroxyl groups are used as generic anchoring sites for further application-specific functionalizations. As an example, we deposited phenolic resin micropatterns on quartz crystal microbalance resonators and further functionalized them with polyethylenimine for preconcentration sensing of humidity and gaseous formic acid. We envision that also preconcentration coatings for other sensing methods, such as attenuated total reflection infrared spectroscopy and surface plasmon resonance spectroscopy, are accessible by this functionalization algorithm.