QCM Sensor Research Articles

Morphology and Wettability of Polystyrene film on QCM Sensor Caused by Oxygen Plasma with DC Bias

Surface wettability and morphology are important aspects of developing QCM sensors for chemical sensors and biosensors. The functionality and morphology of the sensitive coating on the sensor surface affect the sensor sensitivity and selectivity. Various materials and methods to improve the functionality and morphology of the sensor surface have been developed, one of which is plasma. Species and parameters of the generated plasma play an important role in the treatment. One parameter is the DC-bias voltage of RF plasma, which plays an important role in plasma generation and bombardment on the surface being modified. This work shows the effect of the DC bias of the 2 MHz RF plasma with oxygen species. Surface functionality and morphology modification of the polystyrene film on the QCM sensor was done by surface modification using oxygen plasma. Partial etching of the polystyrene film occurred when treated with oxygen plasma generated using 2 MHz with negative DC-bias. CII, CO+, and CO were detected during the exposure of oxygen plasma on polystyrene film, indicating a chemical reaction between the plasma species, oxygen plasma, and the polystyrene. Observation by optical microscope and SEM showed the occurrence of partial etching on the polystyrene film. As there is no masking, the partial etching occurred randomly. The average size of the etched film increased with the DC bias voltage, but the percentage of the etched area was not. The oxygen plasma converts the polystyrene film from hydrophobic to hydrophilic, but hydrophobicity increases with the DC bias voltage. HIGHLIGHTS Polystyrene surface treatment using oxygen plasma can be used to alter the surface hydrophobicity. The DC bias plays important role in the surface modification. High DCV bias gives stronger plasma energy which may etched the polystyrene film. Observation using SEM shows part of the polystyrene film was etched as the DC bias voltage increase. The amount of the etched surface can be measured using optical microscope and processed using ImageJ. Increasing the DC bias result in a wider etched film. GRAPHICAL ABSTRACT

Nanofiber-coated quartz crystal microbalance with chitosan overlay for highly sensitive room temperature ammonia gas sensor

Ammonia is toxic and can pose health risks. Ensuring the safety of individuals working with or around ammonia sensors is crucial, adding complexity to the design and use of such sensors. An ammonia gas sensor by quartz crystal microbalance coated with chitosan-overlaid polyvinyl acetate (PVAc) nanofiber has been studied to have high performance in both sensitivity and selectivity. The scanning electron microscope (SEM) and Fourier-transform infrared (FTIR) spectroscopy were used to analyze the sensing surface, which was the electrospun PVAc nanofiber with chitosan overlay. The nanofiber showed a morphological change and had a more active layer after being overlaid by chitosan. The estimation of PVAc nanofiber thickness on the QCM sensor is (12.0 ± 2.1) µm, measured using a digital microscope. The QCM sensor deposited with PVAc nanofiber only had a sensitivity of 0.076 Hz·ppm−1. It improved to 3.012 Hz·ppm−1 after overlaid with 0.7 wt% chitosan (denoted as PVAc/Ch7 sensor), an increase of 39.6 times. Moreover, the PVAc/Ch7 sensor had a rapid response and recovery times of 9 and 35 s with a very low detection limit of 0.526 ppm. The sensor also exhibited good selectivity toward other analytes. In addition, the sensor also had outstanding in other performances, such as linearity, repeatability, reversibility, and excellent long-term stability. This proposed QCM-based ammonia sensor could be an alternative to analyzing ammonia in various fields.

Coupled vibration and frequency response of a micropillar-enhanced QCM sensor

A theoretical model of a quartz crystal microbalance carrying a layer of substrate and an array of micropillars based on the classical and modified Timoshenko beam theory was established. By choosing specific substrate thickness and micropillar height, this composite sensor approaches the coupled resonance state, and thus significantly improving the mass sensitivity. The intentionally designed sensor is extremely sensitive to tiny mass. However, with increasing mass, the mass sensitivity decreases sharply and then tends to be constant. The frequency shifts calculated by two models have some differences, but their mass sensitivity is almost the same.

Exploring Metal Electroplating for Energy Storage by Quartz Crystal Microbalance: A Review

AbstractThe development and application of Electrochemical Quartz Crystal Microbalance (EQCM) sensing to study metal electroplating, especially for energy storage purposes, are reviewed. The roles of EQCM in describing electrode/electrolyte interface dynamics, such as the electric double‐layer build‐up, ionic/molecular adsorption, metal nucleation, and growth, are addressed. Modeling of the QCM sensor is introduced and its importance is emphasized. Challenges of metal electrode use, including side reactions and dendrite formation, along with their mitigation strategies are reviewed. Numerous factors affecting the electroplating processes, such as electrolyte composition, additives, temperature, and current density, and their influence on the electroplated metals’ mass, structural, and mechanical characteristics are discussed. Looking forward, the need for deeper fundamental understanding and advancing simulations of the QCM signal response as a result of electroplating metal nanostructures is stressed. Further development and integration of innovative EQCM‐strategies will provide unique future means to fundamentally understand and optimize metal electroplating for energy storage and application alike.

Exploring Technology-Driven Technology Roadmaps (TRM) for Wearable Biosensors in Healthcare

ObjectivesThis paper is proposed to identify both promising technologies and potential products in the domain of biosensor using patent-based Technology-Driven Technology Roadmaps (TRM). Materials and methodsThe technology-driven TRM with timelines in this study is developed in three layers: technology, function and product. Patent applications are collected and identified to interpret technologies and functions for biosensors in healthcare, and product manuals or releases can be used as product introductions. ResultsMost biosensors in healthcare patents are concentrated in biochemical (T2) and electroencephalography (T5). Glycated hemoglobin (F1), measuring of glucose (F3), and biological process and molecular systems (F6) have a relatively larger patent count. Biochemical (T2) can combine with biological process and molecular systems (F6), and then brain's real-time electrical activity monitoring can be handled. Biochemical (T2) can also devote to glycated hemoglobin (F1), and glucose monitoring (F3), and thus create QCM sensor, CGM and GlucoWatch etc. applications. ConclusionBiochemical (T2) has a wide application among different functions for wearable biosensors in healthcare. This paper identifies and explores new developments biochemical (T2), and electroencephalography (T5) in wearable biosensors are expected to play a significant role over the coming decade in improving the current healthcare infrastructure, and enhancing the democratization of information and allocation of medical resources.

Highly selective QCM sensor based on functionalized hierarchical hollow TiO2 nanospheres for detecting ppb-level 3-hydroxy-2-butanone biomarker at room temperature

Highly selective QCM sensor based on functionalized hierarchical hollow TiO2 nanospheres for detecting ppb-level 3-hydroxy-2-butanone biomarker at room temperature

A sub-second QCM humidity sensor with low hysteresis base on Nafion thin film

In this paper, we developed a QCM humidity sensor with Nafion thin film coated on its electrode. An impedance-based QCM measurement system proposed in our previous work was used for measurement without oscillators. The experimental results indicate that the obtained QCM sensor has an ultrafast response speed (0.6/0.9 s) and very low hysteresis (1.61% RH). This may be related to the low amount of Nafion on the QCM electrode and the thin enough film generated on it.

System Integration of an Optimally Designed Virtual Impactor with a QCM Sensor as a One-Stop PM2.5 Classification and Detection Platform.

Excessive exposure to airborne particulate matter (PM), especially PM2.5 particles, adversely affects human health. Conventional PM2.5 detection instruments based on light scattering are generally bulky, expensive, and easily affected by particle size and composition. Here, we report a low-cost and compact one-stop PM2.5 detection platform by integrating a three-dimensional (3D) printed virtual impactor with a QCM sensor. To reduce eddy and airflow impact on the side wall and improve the VI lifetime, a computational fluid dynamics simulation is used to optimize the VI structure. Results show that when the included angle between the minor flow channel and the inner side of the major flow channel is 40-45° and the included angle between the inlet channel and the outside wall of the major flow channel is 125°, the VI has a relatively small particle loss, eddy, and good collection efficiency. Finally, the system detection performance is experimentally evaluated with a sensitivity of 0.08 Hz/min per μg/m3, showing a comparable performance with the commercial instrument.

Simultaneous humidity and temperature measurement with micropillar enhanced QCM sensors

In this study, we propose using a polymethylmethacrylate (PMMA) micropillar-based quartz crystal microbalance (micropillar-QCM) sensor for simultaneous measurement of exhaled breath temperature (EBT) and relative humidity (RH). The micropillar-QCM device, fabricated by nanoimprinting lithography, exhibits enhanced sensitivity due to the unique resonance phenomena formed between the vibrating micropillars and quartz substrate. The resonance frequency of the micropillar-QCM shifts in response to changes in the mechanical property – Young’s modulus of PMMA due to the temperature and humidity variations. Experimental results demonstrate that the frequency shift is linearly dependent on the temperature change within the range of 25–35 °C and follows a power law relationship with relative humidity (RH) within the range of 50%− 90%. The sensor exhibits excellent sensitivity in temperature and humidity measurements with limit of detections (LODs) of 0.09 °C and 0.35% respectively. In addition, the temperature change has little effect on the bandwidth of the signal of micropillar-QCM while its bandwidth decreases linearly with the increasing relative humidity. As a result, the combination of the resonance frequency shift and bandwidth of the micropillar-QCM sensor can be utilized to predict the temperature and relative humidity simultaneously. The finding highlights the potential of the micropillar-QCM sensor for applications requiring accurate and real-time temperature and humidity measurements, such as breath analysis, environmental monitoring, and healthcare.

Detection of Citral in some lemongrass essential oil with copolymer composites based QCM Sensor

Detection of Citral in some lemongrass essential oil with copolymer composites based QCM Sensor

Selection of Highly Specific DNA Aptamer for the Development of QCM-Based Arsenic Sensor.

Heavy metal arsenic is a water pollutant that affects millions of lives worldwide. A novel aptamer candidate for specific and sensitive arsenic detection was identified using Graphene Oxide-SELEX (GO-SELEX). Eleven rounds of GO-SELEX were performed to screen As(III) specific sequences. The selected aptamer sequences were evaluated for their binding affinity. The dissociation constant of the best aptamer candidate, As-06 was estimated by fluorescence recovery upon target addition, and it was found to be 8.15 nM. A QCM-based biosensing platform was designed based on the target-triggered release of aptamer from the QCM electrode. An rGO-SWCNT nanocomposite was adsorbed on the gold surface, and the single-stranded probe was stacked on the rGO-CNT layer. Upon addition of the target to the solution, a concentration-dependent release of the ssDNA probe was observed and recorded as the change in the electrode frequency. The developed QCM sensor showed a dynamic linear range from 10 nM to 100 nM and a low detection limit of 8.6 nM. The sensor exhibited excellent selectivity when challenged with common interfering anions and cations.

Artifact Correction of Light Induced Detuning in QCM-D Experiments.

The quartz crystal microbalance with dissipation (QCM-D) has become an efficient and versatile measurement technique for investigating in situ the external stimuli responsiveness such as pH, temperature, or chemical gradients of surface-active substances at solid-liquid interfaces. However, light responsive adsorption investigation is more challenging presumably since the quartz crystal itself reacts to optical stimulation, showing frequency and dissipation shifts known as light induced detuning (LID). This yields an effective measurement artifact and makes data interpretation with respect to dynamic interactions of light responsive materials rather challenging. Here we introduce a simple guideline for correcting the artifacts of the QCM sensor response on irradiation to ensure quantitative analysis for light responsive materials via OCM-D. We also show that the LID depends on the adsorption properties of the sensor and the solvent properties (ionic concentration or viscosity), providing a guideline to minimize impact of the LID.

Design and characterization of Nano cobalt complex as low limit detection qcm sensor for cadmium ions

Design and characterization of Nano cobalt complex as low limit detection qcm sensor for cadmium ions

Development of a portable, low-cost QCM sensor-based device for detecting α-pinene in Indian cardamom

One of the key quality indicators for Indian cardamom is α-pinene. To detect α-pinene, linoleic acid, a constituent fatty acid present in rice bran oil, was found responsible for the physisorption of α-pinene through Van der Waals (vdW) interaction. For the analysis and study of the sensing behaviour of α-pinene, a portable gas measuring device incorporating the rice bran oil coated quartz crystal microbalance sensor (RB-QCM) is developed for real-time detection. The sensor offers a good sensitivity (0.367 Hz/ppm) and a rapid response/recovery time (6 s/11 s). The physical adsorption affinity of α-pinene is calculated using the Langmuir, Freundlich, and Langmuir-Freundlich isotherm models. For estimating α-pinene in cardamom samples, the sensor demonstrated a coefficient of 0.98, with the peak area (%) determined by gas chromatography-mass spectrometry (GC–MS). SEM, FTIR, and AFM are used to analyse the structure and morphology of the sensor coating. According to this study, the rice bran oil-coated QCM sensor is a promising method for detecting α-pinene.

Morphological Evolution of TiO2 Nanoparticle Deposited on QCM Sensor at Various Calcination Temperature

The morphology of TiO2 nanoparticles deposited on a QCM sensor is crucial in its mechanical loading. Different heating treatments transform the morphology of TiO2 nanoparticles, affecting the loading and hence shifting the resonant frequency and changing the impedance QCM value. In this research, the deposition of TiO2 nanoparticles was carried out above QCM using the ultrasonic spray pyrolysis (USP) technique with variations in calcination temperature of 200, 230, and 250 °C. The analysis results show that the increase in the agglomeration and particle size causes an increase in the inertial mass of TiO2 nanoparticles. HIGHLIGHTS The size of TiO2 agglomerates and their particles increases as the calcination temperature is raised Higher calcination temperature resulted in a larger frequency shift of the QCM oscillation due to the layer inertial mass increase Larger TiO2 nanoparticle size significantly increases the layer’s resistance, contributing to higher impedance GRAPHICAL ABSTRACT

Effect of Load on Quartz Crystal Microbalance Sensor Response Addressed Using Fractional Order Calculus.

To accurately model the effect of the load caused by a liquid medium as a function of its viscosity, the fractional order Butterworth-Van Dyke (BVD) model of the QCM sensor is proposed in this study. A comprehensive understanding of the fractional order BVD model followed by a simulation of situations commonly encountered in experimental investigations underpins the new QCM sensor approach. The Levenberg-Marquardt (LM) algorithm is used in two fitting steps to extract all parameters of the fractional order BVD model. The integer-order electrical parameters were determined in the first step and the fractional order parameters were extracted in the second step. A parametric investigation was performed in air, water, and glycerol-water solutions in ten-percent steps for the fractional order BVD model. This indicated a change in the behavior of the QCM sensor when it swapped from air to water, modeled by the fractional order BVD model, followed by a specific dependence with increasing viscosity of the glycerol-water solution. The effect of the liquid medium on the reactive motional circuit elements of the BVD model in terms of fractional order calculus (FOC) was experimentally demonstrated. The experimental results demonstrated the value of the fractional order BVD model for a better understanding of the interactions occurring at the QCM sensor surface.

New Theoretical Model for Mass Sensitivity of Love Wave Sensors

In this work we analyse basic characteristics of Love wave sensors implemented in waveguide structures composed of a lossy viscoelastic surface layer deposited on a lossless elastic substrate. It has to be noted that Love wave sensors working at ultrasonic frequencies have the highest mass density sensitivity $S_σ^(v_p )$ among all known ultrasonic sensors, such as QCM, Lamb wave or Rayleigh wave sensors. In this paper we have established an exact analytical formula for the mass density sensitivity $S_σ^(v_p )$ of the Love wave sensors in the form of an explicit algebraic expression. Subsequently, using this developed analytical formula, we compared theoretically the mass density sensitivity $S_σ^(v_p )$ for various Love wave waveguide structures, such as: (1) lossy PMMA surface layer on lossless Quartz substrate and (2) lossy PMMA on lossless Diamond substrate. The performed analysis shows that the mass density sensitivity $S_σ^(v_p )$ (real and imaginary part) for a sensor with a structure PMMA on Diamond is five times higher than that of a PMMA on Quartz structure. It was found that the mass density sensitivity $S_σ^(v_p )$ for Love wave sensors increases with the increase of the ratio: bulk shear wave velocity in the substrate to bulk shear wave velocity in the surface layer.

Real-time detection of organic acid gases by QCM sensor based on acidified MWCNTs/PANI nanocomposites

Real-time detection of organic acid gases by QCM sensor based on acidified MWCNTs/PANI nanocomposites

Humidity-Mediated QCM Sensor Based on COF-5 for Carbon Dioxide Detection

In this work, covalent organic frameworks (COF-5) are synthesized based on the dehydration reaction of organic ligands and serve as the sensitive layers to realize the reliable detection of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The as-prepared COF-5 based quartz crystal microbalance (QCM) sensor shows a humidity-enhanced CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> response. Under 80% RH, the response to 8000 ppm CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is 154 Hz at room temperature. In addition, the sensor also shows the great selectivity and repeatability. The large specific surface area and -OH group of COF-5 provide the great platform for the adsorption/desorption of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> molecules on the sensitive membrane surface. This work paves the way for rational design of QCM CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensors with the high performances.

A novel molecular imprinted QCM sensor based on MoS2NPs-MWCNT nanocomposite for zearalenone determination.

Zearalenone (ZEN) is a mycotoxin that has a carcinogenic effect and is often found at a high rate in frequently consumed foods. In this study, a characteristic molecular imprinted quartz crystal microbalance (QCM) sensor based on molybdenum disulfide nanoparticle (MoS2NPs)-multiwalled carbon nanotube (MWCNT) nanocomposite (MoS2NPs-MWCNTs) is presented for selective determination of ZEA in rice samples. Firstly, molybdenum disulfide nanoparticle (MoS2NP)-multiwalled carbon nanotube nanocomposites were characterized by using microscopic, spectroscopic, and electrochemical techniques. Then, ZEA-imprinted QCM chip was prepared in the presence of methacryloylamidoglutamicacid (MAGA) as monomer, N,N'-azobisisobutyronitrile (AIBN) as initiator, and ZEA as target molecule by using UV polymerization. The sensor revealed a linearity toward ZEA in the range 1.0-10.0ngL-1 with a detection limit (LOD) of 0.30ngL-1. The high repeatability, reusability, selectivity, and stability of the developed sensorenable reliable ZEA detection in rice samples.