AT-cut Quartz Crystal Research Articles

Surface Roughness Effects on the Vibration Characteristics of AT-Cut Quartz Crystal Plate.

With the miniaturization and high-frequency requirements of quartz crystal sensors, microscopic issues affecting operating performance, e.g., the surface roughness, are receiving more and more attention. In this study, the activity dip caused by surface roughness is revealed, with the physical mechanism clearly demonstrated. Firstly, the surface roughness is considered as a Gaussian distribution, and the mode coupling properties of an AT-cut quartz crystal plate are systematically investigated under different temperature environments with the aid of two-dimensional thermal field equations. The resonant frequency, frequency-temperature curves, and mode shapes of the quartz crystal plate are obtained through the partial differential equation (PDE) module of COMSOL Multiphysics software for free vibration analysis. For forced vibration analysis, the admittance response and phase response curves of quartz crystal plate are calculated via the piezoelectric module. The results from both free and forced vibration analyses demonstrate that surface roughness reduces the resonant frequency of quartz crystal plate. Additionally, mode coupling is more likely to occur in a crystal plate with a surface roughness, leading to activity dip when temperature varies, which decreases the stability of quartz crystal sensors and should be avoided in device fabrication.

A Quartz Crystal Microbalance (QCM) Study on the Formation of Aqueous κ-Carrageenan-Chitosan Composite Bilayers with NaCl and Graphene Oxide

Biomaterials and thin biofilms play a fundamental role in the medical, food and pharmaceutical industries. The Quartz crystal microbalance (QCM) measurement technique is one of the attractive techniques which have been used for monitoring the thin-film formation process. In the current work described here, κ-carrageenan and chitosan solutions were used for the layer-by-layer (LBL) deposition of polyelectrolyte multilayers (PEMs) on the gold surface of a 5 MHz AT-cut (thickness-shear mode) quartz crystal in a flow module. A sensitive QCM system was designed to detect 0.1 Hz differences in the resonance frequency (Δf) and 10−7 changes in the energy dissipation (ΔD) values, which are the measures of the deposited mass and the film rigidity, respectively. Negatively charged carrageenan and positively charged chitosan biomolecules in the solutions were used to build up sequential and very thin bilayers on the modified gold surface. The effects of NaCl and graphene oxide (GO) addition on the mass of the deposited films were also investigated. Intermolecular interactions between the biopolymer chains, Na+ cations and GO sheets were explained by interactions between molecules, such as electrostatic forces and hydrogen bondings.

Real‐Time Quantification of Cell Mechanics and Functions by Double Resonator Piezoelectric Cytometry – Theory and Study of Cellular Adhesion of HUVECs

AbstractCell mechanics is closely associated with cellular structure and function. However, the inability to measure both cellular force and viscoelasticity of statistically significant number of cells noninvasively remains a challenge for quantitative characterizations of various cellular functions and practical applications. Here a double resonator piezoelectric cytometry (DRPC), using AT and BT cut quartz crystals of the same frequency and surface morphology is developed to simultaneously quantify the cells‐generated forces (ΔS) and viscoelastic moduli (G′, G″) of a population of isolated single cells or cells with different degrees of cell‐cell interactions in a non‐invasive and real time manner. DRPC captures the dynamic mechanical parameters ΔS and G′, G″ during the adhesions of human umbilical vein endothelial cells (HUVECs) under different ligand densities of adhesion molecules fibronectin or Arg‐Gly‐Asp (RGD) modified on the gold surfaces of 9 MHz AT and BT cut quartz crystals, and different seeding densities of HUVECs. It is found that both the ligand density and cell seeding density affect the magnitudes of ΔS and G′, G″ and their correlations are revealed for the first time by DRPC. The validity of DRPC is further verified by mechanical changes of the cells in response to treatments with cytoskeleton regulators.

The Multi-field Coupled Vibration Analysis of AT-Cut Quartz Crystal Resonators with Parallelism Error

The Multi-field Coupled Vibration Analysis of AT-Cut Quartz Crystal Resonators with Parallelism Error

A Novel Method in Identifying Pyroptosis and Apoptosis Based on the Double Resonator Piezoelectric Cytometry Technology

In this study, a double resonator piezoelectric cytometry (DRPC) technology based on quartz crystal microbalance (QCM) was first employed to identify HeLa cell pyroptosis and apoptosis by monitoring cells' mechanical properties in a real-time and non-invasive manner. AT and BT cut quartz crystals with the same frequency and surface conditions were used concurrently to quantify the cells-exerted surface stress (ΔS). It is the first time that cells-exerted surface stress (ΔS) and cell viscoelasticity have been monitored simultaneously during pyroptosis and apoptosis. The results showed that HeLa pyroptotic cells exerted a tensile stress on quartz crystal along with an increase in the elastic modulus (G'), viscous modulus (G″), and a decrease of the loss tangent (G″/G'), whereas apoptotic cells exerted increasing compressive stress on quartz crystal along with a decrease in G', G″ and an increase in G″/G'. Furthermore, engineered GSDMD-/--DEVD- HeLa cells were used to investigate drug-induced disturbance and testify the mechanical responses during the processes of pyroptosis and non-pyroptosis. These findings demonstrated that the DRPC technology can serve as a precise cytomechanical sensor capable of identifying pyroptosis and apoptosis, providing a novel method in cell death detection and paving the road for pyroptosis and apoptosis related drug evaluation and screening.

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.

Application of Multiharmonic QCM-D for Detection of Plasmin at Hydrophobic Surfaces Modified by β-Casein

Plasmin protease plays an important role in many processes in living systems, including milk. Monitoring plasmin activity is important for control of the nutritional quality of milk and other dairy products. We designed a biosensor to detect the proteolytic activity of plasmin, using multiharmonic quartz crystal microbalance with dissipation (QCM-D). The β-casein immobilized on the hydrophobic surface of 1-dodecanethiol on the AT-cut quartz crystal was used to monitor plasmin activity. We demonstrated detection of plasmin in a concentration range of 0.1–20 nM, with the limit of detection about 0.13 ± 0.01 nM. The analysis of viscoelastic properties of the β-casein layer showed rapid changes of shear elasticity modulus, μ, and coefficient of viscosity, η, at plasmin sub-nanomolar concentrations, followed by modest changes at nanomolar concentrations, indicating multilayer architecture β-casein. A comparative analysis of viscoelastic properties of β-casein layers following plasmin and trypsin cleavage showed that the higher effect of trypsin was due to larger potential cleavage sites of β-casein.

Machine learning approach to optimization of parameters for impedance measurements of Quartz Crystal Microbalance to improve limit of detection

Impedance spectroscopy allows real time monitoring of fundamental resonance frequency and harmonics of AT cut Quartz Crystal Microbalance (QCM) biosensors. Acquisition of accurate and high resolution spectroscopic data requires optimization of parameters, which is rarely performed as it requires an excessive number of experiments. In this work, machine learning clustering and classification algorithms are applied in an attempt to minimize the number of experiments by designating a small representative subset of chosen values of parameters, while preserving the variation of those values. Our results indicated it is possible to reduce the number of experiments required by more than 10 fold. The constructed model has both an unsupervised clustering part (k-means algorithm) and a supervised classification part (Support Vector Machine algorithm), working independently. From those two different approaches 83% compatibility is obtained. Such optimization can improve limit of detection (LOD) of glycerol concentrations by a factor of 12 using a QCM with a fundamental resonance frequency of 10 MHz. This approach can be applied not only to biosensors but also to chemical sensors involving resonance frequency monitoring by means of impedance spectroscopy, and has the potential to be expanded to systems with different transducer types, monitoring resonance by other means.

Label-Free Real-Time Detection of HBsAg Using a QCM Immunosensor.

Hepatitis B virus surface antigen (HBsAg) is an important protein in both diagnosis and prevention of hepatitis B infection. In the current study, a piezoelectric immunosensor based on antibody-antigen interaction was designed to detect HBsAg. A quartz crystal microbalance system was employed to detect antibody-antigen interaction. At first, an oscillator was designed to measure the resonant frequency affected by the reactants using IC 74LVC1GX04. Antibody against HBsAg was immobilized on 10 MHz AT-cut quartz crystal. The surface modifications were monitored by atomic force microscopy (AFM) and contact angle measurements. Different concentrations of antibody were used for surface immobilization and the frequency shifts were assessed. The system stability was studied by evaluating the stability of the crystal and the immobilized antibody. The adsorption of antibody onto the crystal was analyzed using AFM and changes in the resonance frequency. Further, a direct immunoassay was performed with this immobilized antibody to identify HBsAg solutions at different concentrations. Finally, specific and non-specific responses were investigated using hepatitis B (HBsAg) and hepatitis C (HCV Ag) antigens, respectively. Antibodies against HBsAg were successfully immobilized on 10 MHz AT-cut quartz crystal. The stability tests of crystal immobilized with antibody and unimmobilized crystal revealed that both forms of crystals were stable. Theoretical and experimental frequency assays were compared. A decrease in the contact angle indicated the hydrophilicity of surface after modifications. AFM images illustrated a more uniform surface after antibody adsorption and the surface roughness (RMS) reduced from 1.13 to 0.99 nm. Changes in the frequency were detected after the physical adsorption of HBsAb on the designed chip. The standard curve of antigen revealed the frequency changes depend on concentration of antigen. Finally, the specificity test confirmed the specificity of the designed biosensor for the detection of HBsAg from HCV Ag. The quantization of immobilized antibody was characterized by the frequency shift of the QCM. The obtained results were compared with ELISA assay. The correlation coefficients of HBsAg dilution between QCM and ELISA was 0.9821. This study is a new step to meet the challenges regarding HBsAg detection. Physical adsorption used in this study was effective as the simplest immobilization method to design a QCM-based immunosensor for HBsAg detection. Facilitated, fast, and simple detection of HBsAg by an antibody-based QCM biosensor is our main objective.

UV Light Detection Using Resonance Frequency of Piezoelectric Quartz Crystal

This article reported about the ultraviolet (UV) radiation effect on the resonance frequency response of a AT-cut piezoelectric quartz crystal. A large resonance frequency upshift was observed when the quartz crystal was irradiated by UV light of 355-nm wavelength using a Q-switched pulsed Nd:YVO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> UV laser. The dynamic frequency response behavior was systematically investigated by illuminating the quartz crystal with UV light in which the UV intensity was varied with time in staircase- and linear pulse-shaped patterns. From the experimental analysis, we measured the limit of detection and the sensitivity of the quartz crystal, which are about 0.5 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 0.706 Hz/(mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), respectively. For a constant UV irradiation, a moderate response (<;10 s) and recovery (<;10 s) times were achieved during the on and off cycles of the UV light. The short-term repeatability and maximum operating limit of AT-cut quartz crystal were also further studied upon exposure to UV light with different intensities. In this work, we not only demonstrate the impact of UV irradiation on quartz crystal but also discuss the mechanism of upshift in resonance frequency upon exposure to UV light. This study shows the applicability of quartz crystal for the detection of UV light.

Development of a Low-Cost Portable Gas Sensing System Based on Molecularly Imprinted Quartz Crystal Microbalance Sensor for Detection of Eugenol in Clove Oil

A low-cost portable gas sensing system for the detection of eugenol in clove oil is described in this article. The sensor has been developed on a molecularly imprinted polymer (MIP) modified quartz crystal microbalance (QCM) platform. The system has two parts: 1) MIP-QCM sensor and 2) sensor signal measuring unit, which includes a crystal oscillator (10 MHz), a frequency counter (ATmega328P microcontroller unit), a liquid crystal display (LCD), and a data storage unit. A 10-MHz AT cut quartz crystal was coated with the synthesized solution of the optimum ratio of styrene, methyl methacrylate, and divinylbenzene with eugenol as the template. A crystal oscillator based on a simple complementary metal-oxide-semiconductor inverter and ATmega328 microcontroller were used for data generation and transfer. The portable instrument was used for the detection of eugenol in clove oil samples, which revealed reasonably good repeatability (96.37%), reproducibility (92.92%), and fast response time of about 1 min. The system could detect the concentration of eugenol at ppm level in different real samples. Finally, the response of the proposed system was correlated with the response obtained from gas chromatograph.

Application of QCM in Peptide and Protein-Based Drug Product Development

AT-cut quartz crystals vibrating in the thickness-shear mode (TSM), especially quartz crystal resonators (QCRs), are well known as very efficient mass sensitive systems because of their sensitivity, accuracy, and biofunctionalization capacity. They are highly reliable in the measurement of the mass of deposited samples, in both gas and liquid matrices. Moreover, they offer real-time monitoring, as well as relatively low production and operation costs. These features make mass sensitive systems applicable in a wide range of different applications, including studies on protein and peptide primary packaging, formulation, and drug product manufacturing process development. This review summarizes the information on some particular implementations of quartz crystal microbalance (QCM) instruments in protein and peptide drug product development as well as their future prospects.

High-Performance QCM Humidity Sensors Using Carbon Nanostructure Material as Sensing Film

Introduction Nowadays, sensors have become increasingly indispensable. It is particularly worth mentioning that the humidity has gradually become the standard for measuring environmental state and physical health. From the perspective of manufcturing, the performance and technical index of humidity sensors can vary greatly on materials, structures and processes. For instance, multiple sensing technologies including acoustic [1], resistance [2], optical [3], impedance [4],capacitance [5], thermal [6], and resonance [7], etc. have been explored to monitor the humidity. quartz crystal microbalance (QCM) has been proven to be an excellent mass sensing platform for humidity detection according to Sauerbrey’s equation [8].Sensitive material is the key of a QCM sensor. Among various materials, a variety of sensitive materials has been deposited on the electrode surface of QCM for detecting moisture, such as polymer, metal oxides, carbonic materials and so on. In this study, a series of high performance QCM humidity sensors were developed which using multi-walled CNTs (MWCNTs), Graphene quantum dots(GQDs), Chitosan(CS) and their composites as sensing film. The humidity sensing characteristics, such as dynamical response, reproducibility, and hysteresis characteristics were measured and discussed. Furthermore, the adsorption dynamics of water vapor molecules mechanism was also analyzed. Method Characterization Raman spectra were obtained on J-YT64000 Raman spectrometer with 633 nm wavelength incident laser light. The X-ray photoelectron spectroscopy (XPS) analysis was measured on an ESCALAB MK II Xray photoelectron spectrometer using Mg as exciting source. The Fourier transform infrared spectroscopy (FT-IR) spectra of as-prepared were obtained on a WQF-510AFTIR spectrometer, using KBr pellets as the reference. The transmission electron microscopy (TEM) images were taken by a JEM-2100F electron microscope (JEOL, Japan). Fabrication of QCM humidity sensor The QCM substrates used in this work were purchased from Beijing Chenjing Electronic Co., Ltd. China. The QCM was consisted of AT-cut quartz crystal (8 mm diameter) with a fundamental frequency of 10 MHz and silver electrodes (5 mm diameter) were covered on both sides, the electrode leaded two pins for testing purposes. As a typical procedure, the QCM substrates were ultrasonic cleaned by acetone, ethanol and deionized water for 10 min successively, and then dried in an air-tight container which filled with inert nitrogen gas for the whole night at room temperature. The QCM humidity sensor was obtained via dropping the as-prepared composites dispersion by micropipette on the Ag-electrodes surface of the QCM. Then, the modified QCM sensor was put into the foregoing container for at least 12 h. Results and Conclusions The humidity sensing characteristics of prepared QCM sensors were quantified by transforming the RH level ambient and measuring the shift of the vibration frequency. The humidity hysteresis performance, reproducibility and reversibility were also examined respectively. After further study, a plausible mechanism analysis for the above excellent sensitivity was given. In conclusion, an excellent QCM humidity sensor was obtained to detect full RH range. The oscillating circuit and impedance analysis methods have been adopted to examine the dynamic response and recovery behaviors and static humidity sensing performances, respectively. In addition, the intrinsic hydrophilicity is able to provide more water adsorption sites. The optimized QCM sensor demonstrated the highest humidity sensitivity and long-term stability, and tiny humidity hysteresis. The prepared QCM sensor is reliable for monitoring water vapor content in wide humidity range.

MEMS biosensor for monitoring water toxicity based on quartz crystal microbalance.

This paper presents the use of a commercial quartz crystal microbalance (QCM) to investigate live-cell activity in water-based toxic solutions. The QCM used in this research has a resonant frequency of 10 MHz and consists of an AT-cut quartz crystal with gold electrodes on both sides. This QCM was transformed into a functional biosensor by integrating with polydimethylsiloxane culturing chambers. Rainbow trout gill epithelial cells were cultured on the resonators as a sensorial layer. The fluctuation of the resonant frequency, due to the change of cell morphology and adhesion, is an indicator of water toxicity. The shift in the resonant frequency provides information about the viability of the cells after exposure to toxicants. The toxicity result shows distinct responses after exposing cells to 0.526 μM of pentachlorophenol (PCP) solution, which is the Military Exposure Guidelines concentration. This research demonstrated that the QCM is sensitive to a low concentration of PCP and no further modification of the QCM surface was required.

A High Frequency Dual Inverted Mesa QCM Sensor Array with Concentric Electrodes

Quartz Crystal Microbalance (QCM) is a candidate technology for high sensitivity application. This mass sensor's property depends on the piezoelectric property of the AT-cut quartz crystal. QCM has been widely employed for gas detection due to its comparative advantages including high mass sensitivity, potential for array configuration, low cost, ease of fabrication as well as wide range of available sensitive material compatibility. However, its application has been limited due to two main disadvantages of the non-uniform mass sensitivity across the electrodes and lower frequency of operation. In this work, in order to overcome these disadvantages, a novel concentric electrode structure combined with the dual inverted mesa structure has been proposed and implemented. It is demonstrated that the developed and optimized concentric electrode has provided a uniform displacement across the QCM's sensing electrode. In addition, the dual inverted mesa design has been implemented in the QCM array in which a high fundamental resonant frequency of 33 MHz has been achieved without interference between the adjacent channels in the sensor array. The interference between the adjacent high frequency QCM channels has been eliminated and therefore, each QCM can function as an individual gas sensor when coated with the designed sensing layers. For 33 MHz, the interference has been eliminated at the optimal center to center between electrode distance (c2c). In the case of 10 MHz array, c2c value of 6 mm is achieved which is lower than the value of c2c achieved on a traditionally un-etched QCM array which was found equal to 6.5 mm. Therefore, the proposed QCM array design is shown to reduce the overall size while enhancing the device sensitivity, uniformity and performance.

Identification of Bioactive Compounds in Ginger Based on Molecularly Imprinted Polymer Quartz Crystal Microbalance Gas Sensor

Borneol, citral, and geraniol have been investigated as the major bioactive compound commonly found in ginger. In this work, a molecularly imprinted polymer (MIP) coated quartz crystal microbalance (QCM) sensor array has been employed for selective recognition of bioactive compounds in the ginger essential oil. In the experiment, the concentration of these bioactive compounds previously was measured using solid phase micro extraction gas chromatography-mass spectroscopy (SPME-GC/MS). Design of MIPs as the template of target molecules was created using polyacrylic acid (PAA) polymer matrix and three molecular targets (borneol, citral, and geraniol). An array of QCM sensor was prepared using four 9-Mhz AT-cut quartz crystal embedded between vacuum-deposited Au electrodes. For data recording, the headspace system flew the odorant of three varieties of ginger essential oil as positive control odorant and wild ginger essential oil as negative control odorant into the QCM sensor chamber. Then, mass loading in the MIP films caused frequency change of QCM sensor array due to odorant adsorption in a thin layer of MIP. Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to analyse the QCM response sensor. PCA score plot showed segregation of feature response of ginger essential oil with and without the molecular target in the coordinate of principal components. Meanwhile, LDA was able to discriminate training datasets of 80 ginger samples containing borneol, citral, and borneol with accuracy more than 92.50%.

Bulk Acoustic Wave Characteristics of Pseudo Lateral-Field-Excitation on LGT Single Crystal for Liquid Phase Sensing.

In the present study, pseudo lateral-field-excitation (LFE) bulk acoustic wave characteristics on LGT crystals are investigated to increase the sensitivity of LFE devices on the liquid characteristic variations. The cut orientation of LGT crystals for pseudo-LFE is investigated and verified experimentally. For an LFE device in the pseudo-LFE mode, the thickness shear mode wave is excited by the thickness field rather than the lateral field. The present work shows that when the (yxl) 13.8° LGT plate is excited by the electric field parallel to the crystallographic axis x, it operates in the pseudo-LFE mode. Moreover, characteristics of devices including the sensitivity and impedance are investigated. The present work shows that sensitivity of LFE devices to variation of the conductivity and permittivity of the aqueous solution are 9 and 3.2 times higher than those for AT-cut quartz crystal based devices, respectively. Furthermore, it has been found that the sensitivity of the LGT LFE sensor to liquid acoustic viscosity variations is 1.4 times higher than the one for the AT-cut quartz sensor. The results are a critical basis of designing high-performance liquid phase sensors by using pseudo-LFE devices.

Simultaneous stress and mass change measurements arising from laser induced detuning of a quartz crystal microbalance

We report a study of the frequency response of AT and BT cut Quartz Crystal Microbalances (QCMs) to laser illumination. AT and BT cut QCMs have a similar response to mass adsorption but the opposite frequency response to stress levels, allowing the individual contributions to stress and mass desorption induced by the laser light to be quantitatively investigated. A detailed analysis of the transient thermal behaviors in the quartz crystals has also been performed, which yields stress levels that are consistent with the observed results. Our results quantitatively confirm previous suggestions that radial compressive stress is a dominant contributor to the response of the QCM to laser illumination. They also establish a theoretical framework for the analysis of the transient phenomenon to infer temperature shifts and radial stress levels in the system irrespective of whether both AT and BT cut crystals are utilized.

A 0.45 ppm and low phase noise analog crystal oscillator using a four order temperature compensation algorithm

Based on the analysis of the limitations of traditional compensation methods for analog temperature compensated crystal oscillators (ATCXOs), a new compensation algorithm and compensation network for ATCXOs are proposed in this paper. According to the frequency-temperature characteristics of AT-cut quartz crystals, the gain-temperature characteristics of voltage control crystal oscillators (VCXOs) are firstly derived and approximated by cubic functions. To improve the gain-temperature characteristics of ATCXOs, a quartic compensation algorithm and network are derived using curve fitting technique. A proposed design is implemented using 0.40 µm BCD process. Chip measurement results show that the frequency-temperature stability is within ±0.45 ppm over a temperature range of −40 °C to 85 °C. The phase noise levels are −87 dBc/Hz, −113 dBc/Hz, −137 dBc/Hz, and −152 dBc/Hz at 10 Hz, 100 Hz, 1 kHz, and 10 kHz frequency offset of 26 MHz AT-cut crystal, respectively. Compared with existing ATCXO designs in the literature, our proposed ATCXO chip improves the frequency-temperature stability by at least 55%, while maintaining a similarly low level of phase noise.

Detection of flexibly bound adsorbate using the nonlinear response of quartz crystal resonator driven at high oscillation amplitude

Flexibly bound heavy adsorbates as antibodies, biomarkers, microbeads, bacteria do not produce response at quartz resonators accounted by their mass alone, which complicates their acoustic detection. To resolve this problem, an anharmonic detection technique (ADT) has been developed. It generates higher harmonics by applying a high voltage (0.7–10V) fundamental frequency excitation to 14.3MHz AT-cut quartz crystal. Due to non-linearity the parameters of generated oscillations depend on the amplitude A of the applied signal, being proportional to A2 for the fundamental resonance frequency and mainly to A3 for the amplitude of generated 3rd harmonics. The coefficients of proportionality depend on number of attached particles, but not on their mass and can be calculated from the phenomenological model based on Duffing equation with damping. The model was tested in liquids of various viscosity, on composite layer including polymer film with deposited gold nanoparticles and in electrochemical mode for E.-coli adsorption.