Journal articles: 'QCM sensors'

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Miyake, Akiko, Satoshi Komasa, Yoshiya Hashimoto, Yutaka Komasa, and Joji Okazaki. "Adsorption of Saliva Related Protein on Denture Materials: An X-Ray Photoelectron Spectroscopy and Quartz Crystal Microbalance Study." Advances in Materials Science and Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/5478326.

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The aim of this study was to evaluate the difference in the adsorption behavior of different types of bovine salivary proteins on the PMMA and Ti QCM sensors are fabricated by spin-coating and sputtering onto bare QCM sensors by using QCM and X-ray photoelectron spectroscopy (XPS). SPM, XPS, and contact angle investigations were carried out to determine the chemical composition and surface wettability of the QCM surface. We discuss the quality of each sensor and evaluate the potential of the high-frequency QCM sensors by investigating the binding between the QCM sensor and the proteins albumin and mucin (a salivary-related protein). The SPM image showed a relatively homogeneous surface with nano-order roughness. The XPS survey spectra of the thin films coated on the sensors were similar to the binding energy of the characteristic spectra of PMMA and Ti. Additionally, the amount of salivary-related protein on the PMMA QCM sensor was higher than those on the Ti and Au QCM sensors. The difference of protein adsorption is proposed to be related to the wettability of each material. The PMMA and Ti QCM sensors are useful tools to study the adsorption and desorption of albumin and mucin on denture surfaces.

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Regmi, Bishnu P., Puspa L. Adhikari, and Beni B. Dangi. "Ionic Liquid-Based Quartz Crystal Microbalance Sensors for Organic Vapors: A Tutorial Review." Chemosensors 9, no. 8 (July 27, 2021): 194. http://dx.doi.org/10.3390/chemosensors9080194.

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Organic vapor sensors are used in diverse applications ranging from environmental monitoring to biomedical diagnostics. Among a number of these sensors, quartz crystal microbalance (QCM) sensors prepared by coating ionic liquids (ILs) or their composites are promising devices for the analysis of volatile organic compounds (VOCs) in complex chemical mixtures. Ionic liquids are remarkable materials, which exhibit tunable physico-chemical properties, chemical and thermal stability, multiple interactions with diverse group of molecules, and enormous structural variability. Moreover, ILs exhibit viscoelastic properties, and hence these materials are ideal for creation of QCM virtual sensor arrays. While the scientific literature on IL-coated QCM sensors is rapidly growing, there is still much to learn. This manuscript provides a comprehensive review on the development of IL-coated QCM sensors and multi-sensor arrays as well as their applications for the analysis of VOCs in complex mixtures. Furthermore, IL-coated QCM virtual sensor arrays and their applications are presented. A short overview of some of the QCM designs, future research areas, and recommendations are also discussed. This short review is a necessary first step towards standardization and further development of QCM for the analysis of VOCs.

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Varga, Marián, Alexandr Laposa, Pavel Kulha, Marina Davydova, Jiri Kroutil, Miroslav Husak, and Alexander Kromka. "Fabrication of Diamond Based Quartz Crystal Microbalance Gas Sensor." Key Engineering Materials 605 (April 2014): 589–92. http://dx.doi.org/10.4028/www.scientific.net/kem.605.589.

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Synthetic diamond has remarkable properties comparable with natural diamond and hence is a very promising material for many various applications (sensors, heat sink, optical mirrors, cold cathode, tissue engineering, etc.). Nowadays, deposition of diamond films is normally employed in chemical vapor deposition (CVD) usually at high temperatures (800900 °C), what limit its application to high melting substrates. Gravimetric (mass) sensors belong to the major categories of chemical sensors and the most common type of mass sensor is the bulk acoustic quartz crystal microbalance (QCM). This contribution deals with a nanocrystalline diamond (NCD) growth from the H2/CH4/CO2gas mixture at low temperature (400 °C) by pulsed linear antenna microwave plasma system on 10 MHz circular AT-cut quartz resonators substrate. Gas sensor based on the NCD-coated QCM was developed for detection of ammonia (NH3) at room temperature. Measurements not only confirmed the functionality of this first published NCD-coated QCM sensor, but in addition its sensitivity was twofold to a virgin QCM sensor with a gold active layer.

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Julian, Trisna, Aditya Rianjanu, Shidiq Nur Hidayat, Ahmad Kusumaatmaja, Roto Roto, and Kuwat Triyana. "Quartz crystal microbalance coated with PEDOT–PSS/PVA nanofiber for a high-performance humidity sensor." Journal of Sensors and Sensor Systems 8, no. 2 (July 16, 2019): 243–50. http://dx.doi.org/10.5194/jsss-8-243-2019.

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Abstract. Quartz crystal microbalance (QCM) coated with poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate mixed with polyvinyl alcohol (PEDOT–PSS/PVA) nanofiber has been fabricated as a humidity sensor using the electrospinning method. Three types of PEDOT–PSS/PVA nanofiber sensors are fabricated with different needle-to-collector electrospinning distances. The scanning electron microscope images confirm the presence of beads in the nanofiber structure. The results show that the sensor mass deposition increased with the decrease in needle-to-collector distance. The best sensor performance is exhibited by the sample with medium needle-to-collector distance (QCM NF 2). The QCM NF 2 nanofiber sensor shows excellent sensitivity of up to 33.56 Hz per percentage point of relative humidity, with rapid response (5.6 s) and recovery (3.5 s) times, good linearity, excellent repeatability, low hysteresis, and long-term stability and response. The QCM PEDOT–PSS/PVA nanofiber sensor provides a simple method to fabricate high-performance humidity sensors.

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Cao, Yu, Zhong Cao, Jiao Yun Xia, Ju Lan Zeng, and Li Xian Sun. "Calixarene Molecules Immobilized on Gold Substrates of QCM Sensors Based on Self-Assembled Monolayer Technology." Advanced Materials Research 239-242 (May 2011): 2054–57. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2054.

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Four calixarene supramolecular compounds, RCT, PCT, MRCT, and TBCA as active materials, were immobilized on gold substrates of quartz crystal microbalance (QCM) sensors by using L-cysteine self-assembled monolayer (SAM) as a linker. The RCT immobilized QCM sensor possessed the best response characteristics for methanol molecule when the assembling concentration of RCT reached 1.0 mg/mL. The frequency shift response value of the RCT immobilized QCM sensor was in direct proportion to the concentration of methanol vapor with a range of 0 ~ 6000 ppm. Comparing with a gas chromatography, the proposed QCM sensor could be well used for the determination of methanol vapor with a recovery rate of 98.01 ~ 103.9 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reproducibility and stability, showing that the RCT immobilized QCM sensor can be applied for the detection of the methanol vapor of atmospheric polutants in our living environment.

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Kuchmenko and Lvova. "A Perspective on Recent Advances in Piezoelectric Chemical Sensors for Environmental Monitoring and Foodstuffs Analysis." Chemosensors 7, no. 3 (August 26, 2019): 39. http://dx.doi.org/10.3390/chemosensors7030039.

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This paper provides a selection of the last two decades publications on the development and application of chemical sensors based on piezoelectric quartz resonators for a wide range of analytical tasks. Most of the attention is devoted to an analysis of gas and liquid media and to industrial processes controls utilizing single quartz crystal microbalance (QCM) sensors, bulk acoustic wave (BAW) sensors, and their arrays in e-nose systems. The unique opportunity to estimate several heavy metals in natural and wastewater samples from the output of a QCM sensor array highly sensitive to changes in metal ion activity in water vapor is shown. The high potential of QCM multisensor systems for fast and cost-effective water contamination assessments “in situ” without sample pretreatment is demonstrated.

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Rodríguez-Torres, Marcos, Víctor Altuzar, Claudia Mendoza-Barrera, Georgina Beltrán-Pérez, Juan Castillo-Mixcóatl, and Severino Muñoz-Aguirre. "Discrimination Improvement of a Gas Sensors’ Array Using High-Frequency Quartz Crystal Microbalance Coated with Polymeric Films." Sensors 20, no. 23 (December 6, 2020): 6972. http://dx.doi.org/10.3390/s20236972.

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The discrimination improvement of an array of four highly sensitive 30 MHz gas quartz crystal microbalance (QCM) sensors was performed and compared to a similar system based on a 12-MHz QCM. The sensing polymeric films were ethyl cellulose (EC), poly-methyl methacrylate (PMMA), Apiezon L (ApL), and Apiezon T (ApT) and they were coated over the AT-cut QCM devices by the drop casting technique. All the sensors had almost the same film thickness (0.2 μm). The fabricated QCM sensor arrays were exposed to three different concentrations, corresponding to 5, 10, and 15 μL, of ethanol, ethyl acetate, and heptane vapors. The steady state sensor responses were measured in a static system at a temperature of 20 °C and relative humidity of 22%. Our results showed that the 30-MHz sensors have a higher sensitivity than 12-MHz ones (around 5.73 times), independently of the sensing film and measured sample. On the other hand, principal component analysis and discriminant analysis were performed using the raw data of the responses. An improvement of the classification percentage between 12 MHz and 30 MHz sensors was found. However, it was not sufficient, especially for low concentrations. Furthermore, using partition coefficient and discriminant analysis (DA), an improvement of 100% classification of the three samples was achieved for the case of the 30-MHz sensor array.

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Ummah, Auliya Rahmatul, Imam Tazi, and Muthmainnah Muthmainnah. "QCM SENSOR SENSITIVITY ANALYSIS OF SILVER ELECTRODES COATED WITH LIPID MEMBRANE OLEYL ALCOHOL TOWARD NaCl AND HCl." Jurnal Neutrino 11, no. 2 (September 17, 2019): 65. http://dx.doi.org/10.18860/neu.v11i2.6597.

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One of the sensors, which is currently being developed is the QCM sensor. The QCM sensor is a sensor that utilizes the frequency change to detect a change in mass due to a test substance. The use of a QCM sensor includes other forms of electronic tongue sensor that can distinguish five basic flavours on the tongue. QCM sensor can also be varied electrodes using various lipid membranes such as electronic tongues to increase sensor sensitivity. This research aims to determine the sensitivity of the QCM sensor before and after coated with the lipid membrane to NaCl and HCl. The sensitivity of the QCM sensor to NaCl is 1.47 Hz/M for uncoated sensor and 0.63 Hz/M for coated sensor, while the sensitivity of HCl is 4.55 Hz/M for uncoated sensor and 4.93 Hz/M for coated sensor. The difference of the results is caused by the nature of ionization of the compound and the amount of concentration used. The result of the sensitivity research shows that the QCM sensor with Oleyl Alcohol lipid membrane is more sensitive to HCl than NaCl.

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Kusakawa, You, Eiji Yoshida, and Tohru Hayakawa. "Protein Adsorption to Titanium and Zirconia Using a Quartz Crystal Microbalance Method." BioMed Research International 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/1521593.

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Protein adsorption onto titanium (Ti) or zirconia (ZrO2) was evaluated using a 27 MHz quartz crystal microbalance (QCM). As proteins, fibronectin (Fn), a cell adhesive protein, and albumin (Alb), a cell adhesion-inhibiting protein, were evaluated. The Ti and ZrO2 sensors for QCM were characterized by atomic force microscopy and electron probe microanalysis observation, measurement of contact angle against water, and surface roughness. The amounts of Fn and Alb adsorbed onto the Ti and ZrO2 sensors and apparent reaction rate were obtained using QCM measurements. Ti sensor showed greater adsorption of Fn and Alb than the ZrO2 sensor. In addition, amount of Fn adsorbed onto the Ti or ZrO2 sensors was higher than that of Alb. The surface roughness and hydrophilicity of Ti or ZrO2 may influence the adsorption of Fn or Alb. With regard to the adsorption rate, Alb adsorbed more rapidly than Fn onto Ti. Comparing Ti and ZrO2, Alb adsorption rate to Ti was faster than that to ZrO2. Fn adsorption will be effective for cell activities, but Alb adsorption will not. QCM method could simulate in vivo Fn and Alb adsorption to Ti or ZrO2.

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Hu, Jing Ling, Ting Zhou, Yun Fei Zhang, Zhe Wang, Dong Mei Luo, and Zhong Cao. "Detection of Trace Formaldehyde Gas Based on Quartz Crystal Microbalance Sensor in Living Environment." Advanced Materials Research 233-235 (May 2011): 720–23. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.720.

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Using four types of calixarene derivatives (RCT, PCT, MRCT, TBCA) as coating materials, quartz crystal microbalance (QCM) sensors have been examined for detection of toxic formaldehyde gas indoors. The results showed that PCT was the most efficient adsorption coating material for host-guest recognition of formaldehyde molecule, when the coating mass was 43.93 μg. The PCT based QCM sensor possessed a linear response range of 109 ~ 2721 ppm formaldehyde gas. In comparison with gas chromatography method, the QCM sensor had a recovery of 97.98~104.59 % with a good reversibility, stability and reproducibility, showing that the PCT based QCM sensor can be well used for the determination of trace formaldehyde in the living environment.

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He, Ying Fei, Ya Dong Jiang, Hui Ling Tai, and Guang Zhong Xie. "The Investigation of Quartz Crystal Microbalance (QCM) Formaldehyde Sensors Based on PEI-MWCNTs Composites." Advanced Materials Research 1030-1032 (September 2014): 217–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.217.

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The detection of formaldehyde is very necessary and important in both industrial and residential environments. In this paper, a novel quartz crystal microbalances (QCM) formaldehyde gas sensor has been successful fabricated based on Polyethylenimine (PEI)-multi-walled carbon nanotubes (MWCNTs) composite films by the spraying process. The morphology of films was analyzed by scanning electron microscope (SEM), and formaldehyde-sensing properties of sensors were investigated. The results showed that the prepared QCM gas sensor exhibited good response and recovery behaviors towards formaldehyde gas in the concentration range of 0-10 ppm at room temperature, which also has the superior repeatability and selectivity. Moreover, the gas-sensing mechanism of sensors was studied.

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Aleixandre, Manuel, and Takamichi Nakamoto. "Study of Room Temperature Ionic Liquids as Gas Sensing Materials in Quartz Crystal Microbalances." Sensors 20, no. 14 (July 20, 2020): 4026. http://dx.doi.org/10.3390/s20144026.

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Twenty-eight quartz crystal microbalance (QCM) sensors coated with different sensing films were tested and analyzed in this work; twenty-three sensors were coated in different room temperature ionic liquids (RTILs) and five additional QCM sensors were coated with conventional films commonly used as stationary phases in gas chromatography. Four volatile organic compounds (VOCs), in gaseous phase—hexanol, butyl acetate, 2-hexanone, and hexanoic acid—were measured. Two transducer mechanisms were used; resonant frequency shift and resistance shift of a QCM Mason equivalent circuit. The sensors were characterized by their sensitivity to the VOCs and their discrimination power of the four VOCs. The highest separation among VOCs was obtained when frequency and resistance information of both RTIL and conventional films was used, a sensor array composed by two RTILs (1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and 1-hexyl-3-methylimidazolium hexafluorophosphate) and two conventional films (tricresyl phosphate and apiezon-L) was found to improve the Wilks lambda separation for the tested gases two orders of magnitude compared to the Wilks lambda using only a conventional films array.

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Vashist, Sandeep Kumar, and Priya Vashist. "Recent Advances in Quartz Crystal Microbalance-Based Sensors." Journal of Sensors 2011 (2011): 1–13. http://dx.doi.org/10.1155/2011/571405.

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Quartz crystal microbalance (QCM) has gained exceptional importance in the fields of (bio)sensors, material science, environmental monitoring, and electrochemistry based on the phenomenal development in QCM-based sensing during the last two decades. This review provides an overview of recent advances made in QCM-based sensors, which have been widely employed in a plethora of applications for the detection of chemicals, biomolecules and microorganisms.

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Yan, Ying, Yu Ping Guo, Lan Kun Cai, Qiong Wu, Hao Zhou, and Lai Ming Wu. "Environmental Monitoring of Acetic Acid Gas by Thin Film Polyaniline Sensor." Advanced Materials Research 864-867 (December 2013): 913–18. http://dx.doi.org/10.4028/www.scientific.net/amr.864-867.913.

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The acetic acid gas, as a kind of organic pollutants, can cause severe damage to both people and materials, and has received much attention as a problem. In this paper, a QCM sensor coated with the polyaniline film was employed as a gas sensor to detect the content of the acetic acid gas. The polyaniline film was electrochemical polymerized in situ on the silver electrode surface of quartz crystal microbalance (QCM) sensor and employed as sensing film for detection of acetic acid gas. Responses of the QCM sensors coated with the polyaniline film to different concentrations of the acetic acid gas as a function of time was presented. And the frequency shifts of QCM showed a linear correlation of the concentration of acetic acid gas. The result of our experiment fully indicated that the QCM sensor with the polyaniline film appear to respond effectively and sensitively to the acetic acid gas within the range of experimental concentrations. Such sensor will have potential application in our living environment for real-time monitoring.

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He, Ying Fei, Ya Dong Jiang, Hui Ling Tai, and Guang Zhong Xie. "Fabrication and Formaldehyde-Sensing Property of Quartz Crystal Microbalance (QCM) Coated with PVP-MWCNTs Composites." Key Engineering Materials 645-646 (May 2015): 719–23. http://dx.doi.org/10.4028/www.scientific.net/kem.645-646.719.

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In this paper, the quartz crystal microbalance (QCM) sensors coated with polyvinyl pyrrolidone (PVP)-multiwalled carbon nanotubes (MCWNTs) nanocomposite thin films were developed by the spray process, which were used for the detection of low concentration formaldehyde at room temperature. The surface morphology and structure of films was analyzed by scanning electron microscope (SEM), UV-Vis absorption spectrometry, respectively, and the formaldehyde-sensing properties of sensors were investigated. The results showed that the prepared QCM gas sensor exhibited the linear characteristic, fast response, good reproducibility to low concentration formaldehyde within 6 ppm, and the poisoning of films was observed when the formaldehyde concentration exceeded 6ppm. Moreover, the sensitivity of the sensor could achieve up to 1Hz/ppm and had the good stability of response values.

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ŞAHİN SADIK, Evin, Hamdi Melih SARAOĞLU, İlke GÜROL, Mehmet Ali EBEOĞLU, and Fatma Emel KOÇAK. "Determination of blood glucose parameter from human blood serum by using a quartz crystal microbalance sensor coated with phthalocyanines compounds." TURKISH JOURNAL OF CHEMISTRY 44, no. 5 (October 26, 2020): 1293–302. http://dx.doi.org/10.3906/kim-1911-69.

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Determining the blood glucose level is important for the prevention and treatment of diabetes mellitus. We developed a sensor system using Quartz Crystal Microbalance (QCM) to determine the blood glucose level from human blood serum. This study consists of two experimental stages: artificial glucose/pure water solution tests and human blood serum tests. In the first stage of the study, the QCM sensor with the highest performance was identified using artificial glucose solution concentrations. In the second stage of the study, human blood serum measurements were performed using QCM to determine blood glucose levels. QCM sensors were coated with phthalocyanines (Pcs) by jet spray method. The blood glucose values of 96 volunteers, which ranged from 71 mg/dL to 329 mg/dL, were recorded. As a result of the study, human glucose values were determined with an average error of 3.25%.

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Boutamine, M., O. C. Lezzar, A. Bellel, Salah Sahli, Y. Segui, and Patrice Raynaud. "Plasma Polymerized Highly Hydrophobic Hexamethyldisiloxane Layers: Investigation on the Effect of Monomer Flow Rate Related to the Film Gas Sensing Properties." Key Engineering Materials 605 (April 2014): 275–78. http://dx.doi.org/10.4028/www.scientific.net/kem.605.275.

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Hexamethyldisiloxane (HMDSO) thin films coated quartz crystal microbalance (QCM) electrodes have been characterized for the detection of volatile organic compounds (VOCs). The sensitive coatings were plasma polymerized in pure vapor of HMDSO at different flow rates. The QCM based sensors responses were found to be linearly correlated with the concentration of VOCs vapor. It was shown that it is possible to tune the chemical affinity of the sensor by changing the HMDSO flow rate. Contact angle measurements, Fourier transform infrared spectroscopy and scanning electron microscopy were used to study surface wettability, chemical composition and surface morphology of the coated QCM electrodes.

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Guo, Lili, Shuang Chao, Pei Huang, Xiukai Lv, Quanquan Song, Chunli Wu, Yuxin Pei, and Zhichao Pei. "A Universal Photochemical Method to Prepare Carbohydrate Sensors Based on Perfluorophenylazide Modified Polydopamine for Study of Carbohydrate-Lectin Interactions by QCM Biosensor." Polymers 11, no. 6 (June 10, 2019): 1023. http://dx.doi.org/10.3390/polym11061023.

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A universal photochemical method to prepare carbohydrate sensors based on perfluorophenylazide (PFPA) modified polydopamine (PDA) for the study of carbohydrate–lectin interactions by a quartz crystal microbalance (QCM) biosensor was developed. The PFPA was immobilized on PDA-coated gold sensors via Schiff base reactions. Upon light irradiation, the underivatized carbohydrates were inserted into the sensor surface, including mannose, galactose, fucose and N-acetylglucosamine (GlcNAc). Carbohydrate sensors were evaluated for the binding to a series of plant lectins. A kinetic study of the interactions between mannose and concanavalin A (Con A), fucose and Ulex europaeus agglutinin I (UEA-I) were performed. This method can eliminate the tedious modification of carbohydrates, improve the experimental efficiency, and reduce the experimental cost, which is of great significance for the development of QCM biosensors and the study of biomolecular interactions.

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Kosuru, Lakshmoji, Adam Bouchaala, Nizar Jaber, and Mohammad I. Younis. "Humidity Detection Using Metal Organic Framework Coated on QCM." Journal of Sensors 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4902790.

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Quartz crystal microbalance (QCM) coated with poly-4-vinylpyridine (PVP) and metal organic framework HKUST-1 are investigated and compared for humidity sensing. Drop casting method is employed to coat the PVP and HKUST-1 solutions onto the surface of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH) from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times of these sensors are studied. The sensitivities of uncoated, PVP, and HKUST-1 coated QCM sensors are 7 Hz, 48 Hz, and 720 Hz, respectively, in the range of 22% RH–69% RH. The extraction of desorption rate and adsorption energy associated with the adsorption and desorption of water molecules on these surfaces reveals that HKUST-1 has better sensing properties than PVP and uncoated QCM sensors. In this work, the HKUST-1 coated QCM is shown to be a promising material for moisture detection.

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Kim, Min-Hee, In-Keun Yu, and Seong-Ho Choi. "Development of an Ionic Quartz Crystal Microbalance (QCM) Sensors for the Detection of Na+ and K+ in Human Urine." Sensor Letters 17, no. 9 (September 1, 2019): 671–79. http://dx.doi.org/10.1166/sl.2019.4125.

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In this study, we developed a quartz crystal microbalance (QCM) ionic sensor that can determine Na+ and K+ in human urine by the immobilization of crown ether as an ionic selector on a QCM electrode. In detail, –COOH was first introduced onto the QCM electrode surface by electrochemical copolymerization of thiophene and 3-thiopheneacetic acid, and then crown ether was introduced as an ionic selector onto the –COOH-modified QCM electrode by amide bond reaction. The prepared QCM ionic sensor was evaluated by FT-IR spectroscopy, SEM, contact angle, and cyclic voltammetry to confirm its successful fabrication. A prepared QCM ionic sensor with 4′-aminobenzo18-crown-6 adsorbed at 0.344 μg to K+ cation in this experiment. The Na+ cation was 0.360 mg in a human urine sample with a prepared QCM ionic sensor with 4′-aminobenzo-15-crown-5 and the K+ cation in a real human urine sample was 0.280 mg with a QCM ionic sensor with 4-aminobenzo18-crown-6, respectively. According to these results, the prepared QCM ionic sensor could be used to detection of sodium and potassium concentrations in human urine samples.

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Lee, Seung-Woo. "A New Concept for Development of Quartz Crystal Microbalance Fire Prevention Sensors Modified with Nano-Assembled Thin Films." Journal of Disaster Research 10, no. 4 (August 1, 2015): 595–603. http://dx.doi.org/10.20965/jdr.2015.p0595.

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In this report, we describe a new concept for the development of quartz crystal microbalance (QCM) fire prevention sensors modified with nano-assembled thin films. The first example is the fabrication of QCM gas sensors based on alternate adsorption of TiO2and poly(acrylic acid) (PAA) for the sensitive detection of amine odors. The QCM sensors showed a linear response to ammonia at concentrations of 0.3--15 ppm, depending on the deposition cycle of the alternate TiO2/PAA layers. Ammonia binding is based on acid--base interaction with the free carboxylic acid groups of PAA, and the limit of detection of the 20-cycle TiO2/PAA400film under exposure to ammonia was estimated to be 0.1 ppm. The second example, monitoring of relative humidity, used porphyrin-based nano-assembled thin films prepared by a layer-by-layer approach on QCM resonators. These films were also used to detect significant environmental changes (due to smoke, humidity, or hazardous material release), and the results revealed that QCM-based real-environment monitoring devices can be implemented.

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Hu, Ying, Hui Yu, Zhiyong Yan, and Qinfei Ke. "The surface chemical composition effect of a polyacrylic acid/polyvinyl alcohol nanofiber/quartz crystal microbalance sensor on ammonia sensing behavior." RSC Advances 8, no. 16 (2018): 8747–54. http://dx.doi.org/10.1039/c7ra13006f.

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Wang, Zhenqiang, Mingqing Yang, and Junhui He. "Sensing Properties of GO and Amine-Silica Nanoparticles Functionalized QCM Sensors for Detection of Formaldehyde." International Journal of Nanoscience 13, no. 05n06 (October 2014): 1460011. http://dx.doi.org/10.1142/s0219581x14600114.

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In the current work, graphene oxides (GO) and Amine-Functionalized Silica Nanoparticles ( NH 2-SNs) were used as sensing layer on quart crystal microbalance (QCM) for detection of HCHO gas. The GO and NH 2-SNs functionalized QCM resonators all had a significant response to HCHO gas. The sensitivity of GO functionalized QCM resonator is 0.04 Hz/(μg⋅ppm), which is four times as high as that of NH 2-SNs functionalized QCM resonator (0.01 Hz/(μg⋅ppm)). The GO functionalized QCM resonators would be of benefit in area of environmental applications.

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Syritski, V., J. Reut, A. Öpik, and K. Idla. "Environmental QCM sensors coated with polypyrrole." Synthetic Metals 102, no. 1-3 (June 1999): 1326–27. http://dx.doi.org/10.1016/s0379-6779(98)01047-9.

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Eun, Alvin Jin-Cherng, Liqun Huang, Fook-Tim Chew, Sam Fong-Yau Li, and Sek-Man Wong. "Detection of Two Orchid Viruses Using Quartz Crystal Microbalance-Based DNA Biosensors." Phytopathology® 92, no. 6 (June 2002): 654–58. http://dx.doi.org/10.1094/phyto.2002.92.6.654.

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We have developed a piezoelectric DNA-sensor based on DNA-RNA hybridization for the detection of two orchid viruses, Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). Specific oligonucleotide probes modified with a mercaptohexyl group at the 5′-phosphate end were directly immobilized onto 10-MHz AT-cut quartz crystal microbalance (QCM). QCMs coated with such oligonucleotide probes were exposed to test solutions containing viral RNA for hybridization. Various experimental conditions evaluated were (i) DNA probe coating concentration, (ii) sensitivity and specificity of the probes at different hybridization temperatures, and (iii) effects of incubation temperature on the hybridization time. The specific nucleotide probe-coated QCM-based DNA sensors were able to detect both CymMV and ORSV in quantities as low as approximately 1 ng in purified RNA preparations and 10 ng in the crude sap of infected orchids. This is the first application of a DNA biosensor for the detection of plant viruses.

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Wasilewski, Tomasz, Bartosz Szulczyński, Wojciech Kamysz, Jacek Gębicki, and Jacek Namieśnik. "Evaluation of Three Peptide Immobilization Techniques on a QCM Surface Related to Acetaldehyde Responses in the Gas Phase." Sensors 18, no. 11 (November 14, 2018): 3942. http://dx.doi.org/10.3390/s18113942.

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The quartz-crystal microbalance is a sensitive and universal tool for measuring concentrations of various gases in the air. Biochemical functionalization of the QCM electrode allows a label-free detection of specific molecular interactions with high sensitivity and specificity. In addition, it enables a real-time determination of its kinetic rates and affinity constants. This makes QCM a versatile bioanalytical screening tool for various applications, with surface modifications ranging from the detection of single molecular monolayers to whole cells. Various types of biomaterials, including peptides mapping the binding sites of olfactory receptors, can be deposited as a sensitive element on the surface of the electrodes. One of key ways to ensure the sensitivity and accuracy of the sensor is provided by application of an optimal and repeatable method of immobilization. Therefore, effective sensors operation requires development of an optimal method of deposition. This paper reviews popular techniques (drop-casting, spin-coating, dip-coating) for coating peptides on piezoelectric crystals surface. Peptide (LEKKKKDC-NH2) derived from an aldehyde binding site in the HarmOBP7 protein was synthesized and used as a sensing material for the biosensor. The degree of deposition of the sensitive layer was monitoring by variations in the sensors frequency. The highest mass threshold for QCM measurements for peptides was approximately 16.43 µg·mm−2 for spin coating method. Developed sensor exhibited repeatable response to acetaldehyde. Moreover, responses to toluene was observed to evaluate sensors specificity. Calibration curves of the three sensors showed good determination coefficients (R2 > 0.99) for drop casting and dip coating and 0.97 for the spin-coating method. Sensors sensitivity vs. acetaldehyde were significantly higher for the dip-coating and drop-casting methods and lower for spin-coating one.

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Omatu, Sigeru, Hideo Araki, Toru Fujinaka, Mitsuaki Yano, Michifumi Yoshioka, Hiroyuki Nakazumi, and Ichiro Tanahashi. "Mixed Odor Classification for QCM Sensor Data by Neural Network." ADCAIJ: Advances in Distributed Computing and Artificial Intelligence Journal 1, no. 2 (July 1, 2013): 43–48. http://dx.doi.org/10.14201/adcaij2012124348.

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Compared with metal oxide semiconductor gas sensors, quarts crystal microbalance (QCM) sensors are sensitive for odors. Using an array of QCM sensors, we measure mixed odors and classify them into an original odor class beforemixing based on neural networks. For simplicity we consider the case that two kinds of odor are mixed since more than two becomes too complex to analyze the classification results. We have used eight sensors and four kinds of odor are used as the original odors. The neural network used here is a conventional layered neural network. The classification is acceptable although the perfect classification could not been achieved.

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Zou, Rui Fen, Zhong Cao, Ju Lan Zeng, Yun Lin Dai, and Li Xian Sun. "Characteristics and Mechanism for Host–Guest Recognition of Isopropanol Vapor Based on Calixarene Supramolecules." Advanced Materials Research 239-242 (May 2011): 2050–53. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2050.

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The adsorption characteristics of four calixarene supramolecular compounds, like RCT, PCT, MRCT, and TBCA, as coating materials of quartz crystal microbalance sensors responding to isopropanol vapor have been investigated in this paper. The results showed that the RCT was the best coating material for isopropanol vapor when the coating mass reached 20.41 μg. The frequency shift of RCT coated QCM and the concentration of isopropanol vapor had a good linear relationship and sensitivity. Comparing with the gas chromatography, the QCM sensor could be well used for the determination of isopropanol vapor with a recovery rate of 95.22~108.1 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reversibility, reproducibility and stability, indicating that the RCT coated QCM sensor can be applied for the detection of the atmospheric polutant of isopropanol vapor in practice. The mechanism of the calixarene derivative for recognition of the isopropanol molecule has been preliminarily discussed.

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Yao, Yao, Xianhe Huang, Qiao Chen, Zhen Zhang, and Weiwei Ling. "High Sensitivity and High Stability QCM Humidity Sensors Based on Polydopamine Coated Cellulose Nanocrystals/Graphene Oxide Nanocomposite." Nanomaterials 10, no. 11 (November 5, 2020): 2210. http://dx.doi.org/10.3390/nano10112210.

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In this paper, a high sensitivity and high stability quartz crystal microbalance (QCM) humidity sensor using polydopamine (PDA) coated cellulose nanocrystal (CNC)/graphene oxide (GO) (PDA@CNC/GO) nanocomposite as sensitive material is demonstrated. The PDA@CNC was prepared by the self-polymerization action on the surface of CNC, and it acted as filler material to form functional nanocomposite with GO. The material characteristics of PDA@CNC, CNC/GO and PDA@CNC/GO were analyzed by transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The experimental results show that the introduction of PDA@CNC into GO film not only effectively enhanced the sensitivity of GO-based nanocomposite-coated QCM sensor but also significantly maintained high stability in the entire humidity range. The PDA@CNC/GO30-coated QCM humidity sensor exhibited a superior response sensitivity up to 54.66 Hz/% relative humidity (RH), while the change rate of dynamic resistance of the sensor in the humidity range of 11.3–97.3% RH is only 14% that is much smaller than that of CNC/GO-coated QCM. Besides, the effect of the PDA@CNC content on the sensitivity and stability of GO-based nanocomposite-coated QCM humidity was also studied. Moreover, other performances of PDA@CNC/GO-coated QCM humidity sensor, including humidity hysteresis, fast response and recovery and long-term stability, were systematically investigated. This work suggests that PDA@CNC/GO nanocomposite is a promising candidate material for realizing high sensitivity and high stability QCM humidity sensor in the entire humidity detection range.

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LIEBERZEIT, PETER A., ABDUL REHMAN, SADAF YAQUB, and FRANZ L. DICKERT. "NANOSTRUCTURED PARTICLES AND LAYERS FOR SENSING CONTAMINANTS IN AIR AND WATER." Nano 03, no. 04 (August 2008): 205–8. http://dx.doi.org/10.1142/s1793292008001015.

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Chemical sensor layers for environmental applications require optimal selectivity, sensitivity, and long term stability, which can be achieved in artificial matrices. For detecting thiols in air, reversible affinity interactions can be optimized by varying the stoichiometry of molybdenum disulphide nanoparticles to achieve sulphur deficiencies. Generating MoS1.9 increases the quartz crystal microbalance (QCM) sensor responses towards butane thiol by a factor of three. Artificial recognition sites are accessible by molecular imprinting: acrylate copolymers can be tuned in polarity to interact selectively with atrazine in water leading to detection limits below one ppb with QCM sensors. Finally, sensor arrays coated with six different molecularly imprinted polymers (MIP) correctly reproduce the ethyl acetate concentration of a composter over a period of two weeks validated by GC-MS measurements.

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Vaughan, Stephanie R., Rocío L. Pérez, Pratap Chhotaray, and Isiah M. Warner. "Quartz Crystal Microbalance Based Sensor Arrays for Detection and Discrimination of VOCs Using Phosphonium Ionic Liquid Composites." Sensors 20, no. 3 (January 22, 2020): 615. http://dx.doi.org/10.3390/s20030615.

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Herein, we examine two sensing schemes for detection and discrimination of chlorinated volatile organic compounds (VOCs). In this work, phosphonium ionic liquids (ILs) were synthesized and vapor sensing properties examined and compared to phosphonium IL-polymer composites. Pure IL sensors were used to develop a QCM-based multisensory array (MSA), while IL-polymer composites were used to develop an MSA and virtual sensor arrays (VSAs). It was found that by employing the composite MSA, five chlorinated VOCs were accurately discriminated at 95.56%, which was an increase in accuracy as compared to pure ILs MSA (84.45%). Data acquired with two out of three VSAs allowed discrimination of chlorinated VOCs with 100% accuracy. These studies have provided greater insight into the benefits of incorporating polymers in coating materials for enhanced discrimination accuracies of QCM-based sensor arrays. To the best of our knowledge, this is the first report of a QCM-based VSA for discrimination of closely related chlorinated VOCs.

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Susilo, M. Dwiki Destian, Teguh Jayadi, Ahmad Kusumaatmaja, and Ari Dwi Nugraheni. "Development of Molecular Imprinting Polymer Nanofiber for Aflatoxin B1 Detection Based on Quartz Crystal Microbalance." Materials Science Forum 1023 (March 2021): 103–9. http://dx.doi.org/10.4028/www.scientific.net/msf.1023.103.

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Aflatoxin B1 (AFB1) is one of the mycotoxins with the most dangerous poisons and poses a threat to living things. Several detection methods for Aflatoxin B1 (AFB1) with high sensitivity (LC-MS technique, HPLC, ELISA, etc.) still require lengthy preparation time and are not real-time and portable. Aflatoxin B1 (AFB1) detection is one of the major challenges in the field of food safety because Aflatoxin B1 (AFB1) attacks the food and agricultural products sector. One of the potential sensors that can be used as a base for Aflatoxin B1 (AFB1) detection is the Quartz Crystal Microbalance (QCM) sensor. This study examines the performance of the Quartz Crystal Microbalance (QCM) sensor as one of the Aflatoxin B1 detection techniques through the physical deposition method. The Quartz Crystal Microbalance (QCM) sensor modified uses polyvinyl acetate (PVAc) material as a container to embed a molecular model that will be detected through a molecular imprinting polymer (MIP) process coated on QCM using the electrospinning method. The response results show that the value of the sensor response using the MIP process is more significant than without the MIP process. The sensor characteristics demonstrated by the PVAc/AFB 50 sample have a limit of detection (LOD) value is 0.63 ppb, and a limit of quantitation (LOQ) is 1.91 ppb with a coefficient correlation is 0.97 for testing with a concentration range of 5.0 – 40.0 ppb. Therefore, the MIP process in QCM provides a favorable response for the detection of AFB1 in the future.

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Triyana, Kuwat, Agustinus Sembiring, Aditya Rianjanu, Shidiq Hidayat, Riowirawan Riowirawan, Trisna Julian, Ahmad Kusumaatmaja, Iman Santoso, and Roto Roto. "Chitosan-Based Quartz Crystal Microbalance for Alcohol Sensing." Electronics 7, no. 9 (September 8, 2018): 181. http://dx.doi.org/10.3390/electronics7090181.

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Short-chain alcohols are a group of volatile organic compounds (VOCs) that are often found in workplaces and laboratories, as well as medical, pharmaceutical, and food industries. Real-time monitoring of alcohol vapors is essential because exposure to alcohol vapors with concentrations of 0.15–0.30 mg·L−1 may be harmful to human health. This study aims to improve the detection capabilities of quartz crystal microbalance (QCM)-based sensors for the analysis of alcohol vapors. The active layer of chitosan was immobilized onto the QCM substrate through a self-assembled monolayer of L-cysteine using glutaraldehyde as a cross-linking agent. Before alcohol analysis, the QCM sensing chip was exposed to humidity because water vapor significantly interferes with QCM gas sensing. The prepared QCM sensor chip was tested for the detection of four different alcohols: n-propanol, ethanol, isoamyl alcohol, and n-amyl alcohol. For comparison, a non-alcohol of acetone was also tested. The prepared QCM sensing chip is selective to alcohols because of hydrogen bond formation between the hydroxyl groups of chitosan and the analyte. The highest response was achieved when the QCM sensing chip was exposed to n-amyl alcohol vapor, with a sensitivity of about 4.4 Hz·mg−1·L. Generally, the sensitivity of the QCM sensing chip is dependent on the molecular weight of alcohol. Moreover, the developed QCM sensing chips are stable after 10 days of repeated measurements, with a rapid response time of only 26 s. The QCM sensing chip provides an alternative method to established analytical methods such as gas chromatography for the detection of short-chain alcohol vapors.

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Voinova, Marina V. "On Mass Loading and Dissipation Measured with Acoustic Wave Sensors: A Review." Journal of Sensors 2009 (2009): 1–13. http://dx.doi.org/10.1155/2009/943125.

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We summarize current trends in the analysis of physical properties (surface mass density, viscosity, elasticity, friction, and charge) of various thin films measured with a solid-state sensor oscillating in a gaseous or liquid environment. We cover three different types of mechanically oscillating sensors: the quartz crystal microbalance with dissipation (QCM-D) monitoring, surface acoustic wave (SAW), resonators and magnetoelastic sensors (MESs). The fourth class of novel acoustic wave (AW) mass sensors, namely thin-film bulk acoustic resonators (TFBARs) on vibrating membranes is discussed in brief. The paper contains a survey of theoretical results and practical applications of the sensors and includes a comprehensive bibliography.

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Casteleiro-Roca, J. L., J. L. Calvo-Rolle, M. C. Meizoso-Lopez, A. Piñón-Pazos, and B. A. Rodríguez-Gómez. "New approach for the QCM sensors characterization." Sensors and Actuators A: Physical 207 (March 2014): 1–9. http://dx.doi.org/10.1016/j.sna.2013.12.002.

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Sedlak, Petr, Josef Sikula, Jiri Majzner, Martin Vrnata, Premysl Fitl, Dusan Kopecky, Filip Vyslouzil, and Peter H. Handel. "Adsorption–desorption noise in QCM gas sensors." Sensors and Actuators B: Chemical 166-167 (May 2012): 264–68. http://dx.doi.org/10.1016/j.snb.2012.02.058.

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Chao Zhang and Guanping Feng. "Contributions of amplitude measurement in QCM sensors." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 43, no. 5 (September 1996): 942–47. http://dx.doi.org/10.1109/58.535498.

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Auge, Jörg, Peter Hauptmann, Jens Hartmann, Steffen Rösler, and Ralf Lucklum. "New design for QCM sensors in liquids." Sensors and Actuators B: Chemical 24, no. 1-3 (March 1995): 43–48. http://dx.doi.org/10.1016/0925-4005(95)85010-4.

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Jenik, Michael, Alexandra Seifner, Peter Lieberzeit, and Franz L. Dickert. "Pollen-imprinted polyurethanes for QCM allergen sensors." Analytical and Bioanalytical Chemistry 394, no. 2 (March 11, 2009): 523–28. http://dx.doi.org/10.1007/s00216-009-2718-8.

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Kabir, K. M. Mohibul, Samuel J. Ippolito, Glenn I. Matthews, S. Bee Abd Hamid, Ylias M. Sabri, and Suresh K. Bhargava. "Determining the Optimum Exposure and Recovery Periods for Efficient Operation of a QCM Based Elemental Mercury Vapor Sensor." Journal of Sensors 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/727432.

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In recent years, mass based transducers such as quartz crystal microbalance (QCM) have gained huge interest as potential sensors for online detection of elemental mercury (Hg0) vapor from anthropogenic sources due to their high portability and robust nature enabling them to withstand harsh industrial environments. In this study, we determined the optimal Hg0exposure and recovery times of a QCM based sensor for ensuring its efficient operation while monitoring low concentrations of Hg0vapor (<400 ppbv). The developed sensor was based on an AT-cut quartz substrate and utilized two gold (Au) films on either side of the substrate which functions as the electrodes and selective layer simultaneously. Given the temporal response mechanisms associated with mass based mercury sensors, the experiments involved the variation of Hg0vapor exposure periods while keeping the recovery time constant following each exposure and vice versa. The results indicated that an optimum exposure and recovery periods of 30 and 90 minutes, respectively, can be utilized to acquire the highest response magnitudes and recovery rate towards a certain concentration of Hg0vapor whilst keeping the time it takes to report an accurate reading by the sensor to a minimum level as required in real-world applications.

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Xu, Zhangliang, and Yong J. Yuan. "Quantification ofStaphylococcus aureususing surface acoustic wave sensors." RSC Advances 9, no. 15 (2019): 8411–14. http://dx.doi.org/10.1039/c8ra09790a.

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Quartz crystal microbalance (QCM), surface acoustic wave (SAW)-Rayleigh and ZnO based SAW-Love sensors were fabricated and their sensitivity was comparatively analyzed for the quantification ofStaphylococcus aureus(S. aureus).

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Oztuna, Ali, Hasan Nazir, and Mehmet Baysallar. "Simultaneous Bacillus anthracis Spores Detection via Aminated-Poly(vinyl chloride) Coated Piezoelectric Crystal Immunosensor." Journal of Coatings 2014 (August 19, 2014): 1–8. http://dx.doi.org/10.1155/2014/256168.

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Bacillus anthracis spores are a potential threat to countries in the context of biodefense. We have already seen the destructiveness of the anthrax attacks in the recent past. This study presents an aminated-poly(vinyl chloride) (PVC-NH2) coated quartz crystal microbalance (QCM) immunosensor for simultaneous rapid detection of B. anthracis spores. PVC-NH2, synthesized in the laboratory, was used as an adhesive layer for monoclonal antibody immobilization on gold quartz crystal. The prepared QCM sensor was tested using a pathogen field strain of B. anthracis (GenBank number: GQ375871.1) under static addition and flow through procedures with different spore concentrations. Fourier transform infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM) were performed to characterize the surface of the sensor during the modification. Furthermore, a series of SEM micrographs were taken in order to investigate surface morphology and show the presence of the B. anthracis spores on the surface. It is concluded that B. anthracis spores can be accomplished by using amine functionalized polymer coated QCM sensors without requiring complicated immobilization procedures or expensive preliminary preparations.

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Wu, Mei, Guang Zhong Xie, Yong Zhou, and Hui Ling Tai. "A PVP-Based Quartz Crystal Microbalance Sensor for H₂S Detection." Applied Mechanics and Materials 651-653 (September 2014): 191–94. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.191.

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Hydrogen sulfide is a typical toxic, inflammable gas. The detection of H2S is crucial in the areas of oil, natural gas and so on. However, studies on H2S gas sensors at room temperature were seldom reported. In this study, Quartz crystal microbalance (QCM) sensors have been utilized, and PVP film were prepared on the QCM by airbrush method with different airbrush volume for H2S detection. The results showed that the PVP film with airbrush volume 0.2ml exhibited a better sensing response to H2S gas. Besides, sensitive characteristics parameters, i.e. selectivity, stability, linearity and sensitivity of prepared sensors were studied for comparison. The relative sensing mechanism associated with SEM pictures was studied as well.

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Kazantseva, Z. I. "Phosphorylated thiacalixarenes as molecular receptors for QCM sensors of volatile compounds." Functional materials 24, no. 4 (December 18, 2017): 599–606. http://dx.doi.org/10.15407/fm24.04.599.

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Yoshida, Eiji, and Tohru Hayakawa. "Quantitative Analysis of Apatite Formation on Titanium and Zirconia in a Simulated Body Fluid Solution Using the Quartz Crystal Microbalance Method." Advances in Materials Science and Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/7928379.

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The bone-bonding ability of a material is evaluated by examining apatite formation on its surface in simulated body fluid (SBF). Partially stabilized zirconia (ZrO2) is currently attractive as an alternative to titanium (Ti) implants; however, no quantitative analysis of apatite formation between Ti and ZrO2 in SBF has been reported. In the present study, we quantitatively evaluated apatite formation onto Ti or ZrO2 in SBF using the 27 MHz quartz crystal microbalance method (QCM). In the QCM measurements, apatite formation was detected as a frequency decrease in the Ti or ZrO2 sensor. Frequency decreases were observed at around 1 hour for Ti and at around 2 hours for the ZrO2 sensor after the injection of SBF. This revealed that the Ti sensor showed faster apatite formation than ZrO2. There was no significant difference in the amounts of apatite formation between the Ti and ZrO2 sensors after 24 hours of apatite formation in SBF. In conclusion, the present quantitative study using QCM revealed that apatite formation on the Ti surface in the SBF was obviously faster than that on the ZrO2 surface. Faster apatite formation may predict faster initiation of bone formation on Ti compared with ZrO2.

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Lieberzeit, Peter A., Gerd Glanznig, Anton Leidl, and Franz L. Dickert. "Ceramic Materials for Mass-Sensitive Sensors - Detection of VOCs and Monitoring Oil Degradation." Advances in Science and Technology 45 (October 2006): 1799–802. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1799.

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Inorganic frameworks obtained by the sol-gel route can be templated by a molecular imprinting (MIP) approach to generate functional cavities. Such MIP ceramics show highly appreaciable properties for chemical sensor applications, because they are inherently chemically and thermally robust. In combination with mass-sensitive devices (e.g. quartz crystal micro balance – QCM, surface transverse wave oscillator - STW), they yield highly selective and sensitive chemical sensors. Gas phase measurements with volatile organic compounds (VOCs) e.g. lead to sensitivities below 1 ppm. Sensitivity can be tuned by the sol-gel-precursor: when hydrolysing more bulky alkoxides, this leads to enhanced sensitivity by increasing porosity as a consequence of slower solvent evaporation. By adding products of oxidative oil degradation to the sol-gel mixture, we succeeded in generating sensors for degradation processes in these complex matrices. This allows parallelly monitoring both the chemical state of oil and changes in viscosity. Sensitivity is enhanced according to the Sauerbrey equation by going from 10 MHz QCM transducers to higher frequencies either by etching the quartz substrates and so reducing the resonator thickness or by applying STWs.

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Yarman, Aysu, Sevinc Kurbanoglu, Katharina J. Jetzschmann, Sibel A. Ozkan, Ulla Wollenberger, and Frieder W. Scheller. "Electrochemical MIP-Sensors for Drugs." Current Medicinal Chemistry 25, no. 33 (October 24, 2018): 4007–19. http://dx.doi.org/10.2174/0929867324666171005103712.

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In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the ”molecularly imprinted polymer” (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano- up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts.

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Anwar Zainuddin, Ahmad, Anis Nurashikin Nordin, Rosminazuin Ab. Rahim, Aliza Aini Md. Ralib, Sheroz Khan, Cyril Guines, Matthieu Chatras, and Arnaud Pothier. "Verification of Quartz Crystal Microbalance Array using Vector Network Analyzer and OpenQCM." Indonesian Journal of Electrical Engineering and Computer Science 10, no. 1 (April 1, 2018): 84. http://dx.doi.org/10.11591/ijeecs.v10.i1.pp84-93.

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Quartz Crystal Microbalance (QCM) is a device that allows non-destructive measurements of r in situ reaction activities. In this article, an array comprising of six 3MHz QCM sensors in an array were characterized using a vector network analyzer and OpenQCM, a portable measuring instrument that measures change in resonance frequency. Measurements of S21 transmission characteristics using the vector network analyzer provides the resonance frequency and can also be used to derive the RLC equivalent electrical circuit values of a resonant two-port network based on the Butterworth-Van Dyke model. In this work, Rm, Lm, Cm and Co were obtained via curve-fitting of the measurement results to the simulated results. Measurements were done in triplicates to verify reproducibility for all 6 sensors. For comparison, measurements were also done using a portable, open-source instrument, OpenQCM. The OpenQCM instrument directly measures changes in resonance frequencies, making it ideal for biosensing experiments, which correlate changes in mass with changes in resonance frequencies. Comparison between resonance frequency measurements using VNA and OpenQCM exhibit low percentage difference 0.2%. This QCM sensor array has the potential of conducting real-time, point-of-care analyses for detection of biological molecules.

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Yoshioka, Tomohiko, Toshiyuki Ikoma, Akira Monkawa, Toru Tonegawa, Dinko Chakarov, B. Kasemo, Nobutaka Hanagata, and M. Tanaka. "Protein Adsorption on Hydroxyapatite Nano-Crystals with Quartz Crystal Microbalance Technique." Key Engineering Materials 361-363 (November 2007): 1119–22. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.1119.

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Real time adsorption behaviors of six proteins with different isoelectric points on hydroxyapatite (HAp) nanocrystal surfaces have been investigated by using HAp sensors for quartz crystal microbalance with dissipation technique (QCM-D). The dissipation (D)–frequency (f) plots clearly showed that the different types of protein adsorption behaviors; the D-f plots of acidic proteins lie on one straight line with a constant slope under all initial protein concentrations, while those of neutral and basic proteins lie on two straight lines with different slopes. The acidic proteins formed a monolayer, while the neutral and basic proteins could cause conformational changes with the adsorbed amount of proteins. The QCM-D technique with novel HAp nanocrystal sensor is useful for the liquid phase changes of proteins on the surface.

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WYSZYNSKI, B., P. SOMBOON, and T. NAKAMOTO. "Pegylated lipids as coatings for QCM odor-sensors." Sensors and Actuators B: Chemical 121, no. 2 (February 20, 2007): 538–44. http://dx.doi.org/10.1016/j.snb.2006.04.089.

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Journal articles on the topic 'QCM sensors'

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