Silicon-based MEMS resonators have shown promising potential to replace quartz crystal resonators in many fields, especially in realizing precise timing. However, the large temperature-dependent properties of single-crystal silicon render the MEMS resonators suffer from severe degradation in frequency stability caused by temperature variation, thus hindering the development of silicon-based resonant devices. Although oven-controlled MEMS resonators have been demonstrated to achieve ppb-level frequency stability, the on-chip oven control scheme requires a redesign of the resonator structures or even a change in the manufacturing process, offering little post-fabrication flexibility and limiting its engineering applications. In this work, a nonlinearity-mediated temperature compensation scheme is proposed with the objective of rapidly and precisely controlling the frequency stability of the MEMS resonator. By employing the nonlinear amplitude-frequency dependence of a Duffing resonator to actively suppress the frequency drift after the first stage oven control, the reported MEMS resonator exhibits a frequency stability of ±14 ppb.

Analysis of the Local Physicochemical Properties of the Electrolyte at the Dynamic Electrochemical Interface Using the Quartz Crystal Resonator Technique

Abstract Volatile emissions can be efficiently reduced by membrane separation processes. Selecting the most adequate membrane polymer can be a time and resource‐intensive screening process. It is demonstrated that surface‐sensitive techniques such as the quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) can be valuable tools to significantly cut down on the time needed to characterize and quantify vapor‐polymer interactions. Both techniques are shown to be highly complementary. QCM allows also obtaining qualitative data on changes in the polymer viscoelasticity upon vapor sorption which ultimately might permit a correlation with the mechanical membrane stability.

A Multi-Functional VOC Sensor Based on Cascaded Quartz Crystal Resonators

Quantification of Methane in Water at Parts Per Billion Sensitivity Using a Metal–Organic Framework-Functionalized Quartz Crystal Resonator

In this study, an aptamer biosensor for detecting lactoferrin (LF) was developed using piezoelectric quartz-induced bond rupture sensing technology. The thiol-modified aptamer I was immobilized on the gold electrode surface of the quartz crystal microbalance (QCM) through an Au-S bond to specifically bind LF. It was then combined with aptamer-magnetic beads to amplify the mass signal. The peak excitation voltage was 8 V at the resonance frequency for the 60 MHz gold-plated quartz crystal. When the molecular bond cracking process occurred, the aptamer-magnetic beads combined on the surface of the piezoelectric quartz were removed, which resulted in an increase in quartz crystal resonance frequency. Therefore, the specific detection of LF can be realized. Under optimized experimental conditions, the linear range for LF was 10-500 ng/mL, the detection limit (3σ) was 8.2 ng/mL, and the sample recoveries for actual milk powder samples ranged from 97.2% to 106.0%. Compared with conventional QCM sensing technology, the signal acquisition process of this sensing method is simple, fast, and easy to operate.

Practical limits of the quartz crystal microbalance and surface plasmon resonance for elucidating salt or ion partitioning into membrane polymers

Abstract Quartz Crystal Resonators (QCR) are fundamental components of Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) sensors, which are highly sensitive to temperature. First, theoretical and finite element models of an AT-cut QCR considering temperature coupling are established. Subsequently, the effects of quartz substrate shape and thermal stress on the amplitude and dissipation factor of the resonator across a broad temperature range are analyzed by using the constructed finite element simulation model. The results indicate that the dissipation factor shows little correlation with the shape and thermal stresses across a broad range of temperature fluctuations. The amplitude decreases gradually as the temperature rises, and the circular substrate experiences a relatively smaller rate of change compared to the squared one. Additionally, thermal stresses contribute to reducing the resonator’s amplitude.

This study focuses on the influence of electrospray deposition parameters on the morphology, topography, optical and sensing properties of ZnO films deposited on gold electrodes of quartz crystal resonators. The substrate temperature, precursor feed rate and emitter's voltage were varied. Zinc acetate dehydrate dissolved in a mixture of deionized water, ethanol and acetic acid was used as a precursor. The surface morphology and average roughness of the films were studied by scanning electron microscopy (SEM) and 3D optical profilometry, respectively, while the optical properties were investigated by diffuse reflectance and photoluminescence measurements. The sensing response toward ammonia was tested and verified by the quartz crystal microbalance (QCM) method. The studies demonstrated that electrospray deposition parameters strongly influence the surface morphology, roughness and gas sensing properties of the films. The deposition parameters were optimized in order for the highest sensitivity toward ammonia to be achieved. The successful implementation of the electrospray method as a simple, versatile and low-cost method for deposition of ammonia-sensitive and selective ZnO films used as a sensing medium in QCM sensors was demonstrated and discussed.

This study explores the sensing capabilities of chemical vapor deposition (CVD)-grown graphene in detecting volatile organic compounds (VOCs) through quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. Two distinct sensing devices were developed, each tailored for QCM and SPR transducing mechanisms, utilizing CVD graphene as the sensing element. The sensors demonstrated consistent and reproducible responses when exposed to various concentrations of dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, and m-xylene. Notably, both sensors exhibited unparalleled sensitivity to dichloromethane, with the graphene-coated SPR sensor displaying a sensitivity value of 294 × 10−3 ppm−1 and a limit of detection (LOD) value of 10.62 ppm. Additionally, the SPR sensor showcased remarkably swift response and recovery times, both under 3 sec. Results indicate that the adsorption of VOC molecules on the CVD graphene surface increases with the rising dipole moments and vapor pressure values of the molecules. The utilization of CVD graphene in both sensing approaches demonstrates good reproducibility in detecting ultralow concentrations of VOCs at room temperature.

Optimization of AT-cut Quartz Crystal Resonator Shape on the Support Substrate

Liquid Density Measurement in High-Pressure Region Using Quartz Crystal Resonators

In this study, the destabilization of asphaltenes in a crude oil sample was analyzed under various pressure conditions using a fully immersed Quartz Crystal Resonator (QCR) sensor. Firstly, oil samples with and without a chemical additive were tested at atmospheric pressure through titration with different liquid n-alkanes (C7, C9, and C12) as antisolvents. Then, high-pressure experiments (HP) were conducted on a recombined crude oil + gas system, involving constant mass expansions from 1000 bar to the saturation pressure point at various fixed temperatures. From these high-pressure experiments, the phase diagrams, including the asphaltene pressure envelope (APE), were constructed and compared for the recombined oil with and without the chemical additive in both P vs T and P vs composition diagrams. The results regarding the impact of the chemical additive under HP conditions were compared with those obtained under atmospheric pressure conditions. The comparison shows an strong agreement between the two sets of experiments, confirming that the test conducted to evaluate the effectiveness of asphaltene inhibitors can be extrapolated to high-pressure applications.

Quartz crystal resonators (QCRs) can be described by four parameters in the BVD-equivalent circuit: static capacitance (C 0), motional capacitance (C 1), motional inductance (L 1), and motional resistance (R 1). In this study, we propose a set of formulae through theoretical deduction to evaluate these four parameters using the impedances of QCRs at different frequencies. Using this method, engineers can evaluate the four parameters without theoretical errors in only one frequency sweep. The method has been verified by LTspice simulation. In the simulation, the average error was 0.35%, which demonstrated its correctness. Meanwhile, in practical measurements, compared to the parameters reported by 250B, the parameters calculated using this method demonstrated better fitting ability. Moreover, the calculation process was simple. Therefore, the measuring procedures and apparatus can be simplified using this method.

This paper presents a new clustering method for identifying the vibration mode shapes of piezoelectric resonators using image processing and principal component analysis (PCA). The finite element method (FEM) is an indispensable tool for analyzing the vibration-displacement distribution of resonators and suppressing spurious vibration modes. Although the FEM exports eigenfrequencies as a list, including spurious vibration modes, recognizing the vibration shape of each eigenfrequency requires manual operation by operators to view the displacement distribution and identify the vibration shapes. The proposed method consists of a preprocessing step based on a threshold selection before the PCA step. Preprocessing significantly simplifies the vibration displacement distribution and reduces the amount of data required for post-processing PCA. The mode chart of the AT-cut quartz crystal resonator obtained using the proposed method agreed with Koga’s experimental results. The proposed method enables the generation of mode charts with reduced processing and computational resources.

Quartz Crystal Resonator Force Sensor combined with the high-efficiency stress concentration mechanism

Microalgae cell adhesions on hydrophobic membrane substrates using quartz crystal microbalance with dissipation.

Purpose This paper aims to apply the novel numerical model to analyze the effect of pillar material on the response of compound quartz crystal resonator (QCR) with an array of pillars. The performance of the proposed device compared to conventional QCR method was also investigated. Design/methodology/approach A finite element method model was developed to analyze the behavior of QCR coupled with an array of pillars. The model was composed of an elastic pillar, a solution and a perfectly matched layer. The validation of the model was performed through a comparison between its predictions and previous experimental measurements. Notably, a good agreement was observed between the predicted results and the experimental data. Findings The effect of pillar Young’s modulus on the coupled QCR and pillars with a diameter of 20 µm, a center-to-center spacing of 40 µm and a density of 2,500 kg/m3 was investigated. The results indicate that multiple vibration modes can be obtained based on Young’s modulus. Notably, in the case of the QCR–pillar in air, the second vibration mode occurred at a critical Young’s modulus of 0.2 MPa, whereas the first mode was observed at 3.75 Mpa. The vibration phase analysis revealed phase-veering behavior at the critical Young’s modulus, which resulted in a sudden jump-and-drop frequency shift. In addition, the results show that the critical Young’s modulus is dependent on the surrounding environment of the pillar. For instance, the critical Young’s modulus for the first mode of the pillar is approximately 3.75 Mpa in air, whereas it increases to 6.5 Mpa in water. Originality/value It was concluded that the performance of coupled QCR–pillar devices significantly depends on the pillar material. Therefore, choosing pillar material at critical Young’s modulus can lead to the maximum frequency shift of coupled QCR–pillar devices. The model developed in this work helps the researchers design pillars to achieve maximum frequency shift in their measurements using coupled QCR–pillar.

Influence of humidity on accuracy of QCM – IR780-based GUMBOS sensor arrays

Gas sensors based on quartz crystal microbalance (QCM) are used to measure mass changes through frequency shifts, using the piezoelectric principle. These sensors are employed in odor detection and are essential for the development of electronic noses. For optimal performance, a sensitive film is applied to the surface of the crystal electrode, which is compatible with a specific compound. There are different methods of film deposition: ultrasonic atomization, spray coating, and casting. The casting method, which involves the manual application of sensitive films using a micropipette, is the most commonly used. However, it is not reproducible. To improve the casting method, a mechanism is proposed as a preliminary platform for a sensitive film application system. The objective is to achieve reproducibility in the construction of gas sensors by applying ethyl cellulose sensitive films onto the sensor surface, thereby reducing the margin of error. Tests were performed on the mechanism to verify the capabilities of the system for the deposition of sensing films using joysticks based on the resistance change principle.