石英晶体微天平在液相中的振荡理论及应用

压电石英晶体微天平在液相中的振荡理论有质量效应理论、振荡边界层理论、耦合理论电解质效应理论,介电效应理论和非质量效应综合理论。     

一种简易的电化学石英晶体微天平自动记录电路

介绍了一种简易的电化学石英晶体微天平（ＥＱＣＭ）自动记录电路，可利用常用的Ｘ－Ｙ记录仪，在 位条件下同时记录电极上的质量变化和电信号变化。用铜的恒电流电沉积验证了ＥＱＣＭ的质量灵敏度，结果符合Ｓａｕｅｒｂｒｅｙ方程。仪器已初步用于镍电极对１，４－丁炔二醇吸附的观察。     

石英晶体传感器系统在检测领域的应用

回顾了石英晶体传感器系统在检测领域的应用。并根据在研发过程中容易遇到的问题，在应用层面提出了解决这些问题的技术和方法。最后简述了相关领域的最新研究动向。     

石英晶体微天平气敏传感器阵列测量系统

为克服现有单气敏传感器测量系统非自动识别气体种类和浓度的缺陷,采用一种基于以太网传输协议的32通道石英晶体微天平(QCM)测量系统。该系统由QCM气敏传感器阵列起振模块和高精度频率计数卡组成。起振模块产生32路石英晶体频率信号;高精度频率计数卡通过FPGA内部计数器直接采样频率信号,通过以太网高速传输到上位机进行数据存储、数据处理及信号波形显示。测试结果表明:系统可以实现实时、多通道、高速、高精度采集和发送数据。     

用于aPTT测量的Parylene-C增强型石英晶体微天平耗散检测系统

房颤、血栓等患者抗凝药物日常口服等场景迫切需要凝血参数快速检测,本文设计和制作了一种Parylene-C增强型石英晶体微天平(QCM)传感器及其耗散因子检测系统用于凝血测量。首先使用Parylene-C有效增加石英晶体微天平传感器的峰峰值和有效使用次数,基于传感器耗散因子对血液凝固过程血液粘弹性变化敏感,设计电导谱分析法的压电传感器耗散因子快速测量系统,对血浆部分凝血活酶时间(aPTT)进行测量。并用SYSMEX CS 5100光学凝血仪、Lambda 950分光光度计验证系统测量结果。实验表明,Parylene-C增强型QCM传感器信号峰峰值增加8±1%,传感器aPTT实验有效重复使用次数为30次,系统30℃温差最大耗散偏移2.09×10-6。aPTT耗散曲线与光学法(lambda950)吸光度曲线变化趋势一致。与SYSMEX CS 5100临床结果线性拟合决定系数R2为0.99。同样本10次重复实验结果变异系数为1.48%。Parylene-C增强型QCM传感器与耗散分析法的联合应用具备多场景下凝血参数快速检测的能力,系统温度稳定性好,具有满足即时检测应用的潜力。     

石英晶体温度传感器的原理及应用

石英晶体是弹性体,它存在固有振动频率.当强迫振动频率等于它的固有振动频率时,就会产生谐振.利用这一特性人们将它做成振荡器、压电传感器等元件.通常,用于这些方面的石英晶体,它的温度稳定性是衡量其品质的一项重要指标.由于石英晶体的固有振动频率与温度密切相关,因此,我们可以利用这一特点作成高精度的温度一频率传感器.     

石英晶体微量天平在分析化学中的应用

本文介绍近年来石英晶体微量天平(QCM)在大气污染检测、工业生产过程控制及液相色谱分析领域中应用的概况。     

薄型石英晶体半波片的制造

介绍薄型石英晶体半波片的平面和侧面加工。     

石英晶体粘度传感器原理及特性研究

介绍了石英晶体粘度传感器的原理、结构及振荡电路组成。通过实验分析了传感器的响应时间、探头插入深度的影响、温度特性以及粘度灵敏度。     

Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications

The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequency/mass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed.     

Improved frequency/voltage converters for fast quartz crystal microbalance applications

The monitoring of frequency changes in fast quartz crystal microbalance (QCM) applications is a real challenge in today's instrumentation. In these applications, such as ac electrogravimetry, small frequency shifts, in the order of tens of hertz, around the resonance of the sensor can occur up to a frequency modulation of 1 kHz. These frequency changes have to be monitored very accurately both in magnitude and phase. Phase-locked loop techniques can be used for obtaining a high performance frequency/voltage converter which can provide reliable measurements. Sensitivity higher than 10 mVHz, for a frequency shift resolution of 0.1 Hz, with very low distortion in tracking both the magnitude and phase of the frequency variations around the resonance frequency of the sensor are required specifications. Moreover, the resonance frequency can vary in a broad frequency range from 5 to 10 MHz in typical QCM sensors, which introduces an additional difficulty. A new frequency-voltage conversion system based on a double tuning analog-digital phase-locked loop is proposed. The reported electronic characterization and experimental results obtained with conducting polymers prove its reliability for ac-electrogravimetry measurements and, in general, for fast QCM applications.     

Development of a magnetic quartz crystal microbalance

A new technique for measurement of magnetic properties of materials is demonstrated. It can be used for the measurement of thin magnetic films during their chemical modification. The resonance frequency of a quartz crystal microbalance (QCM) with conducting polymer (polyaniline) suspension in poly(ethylene glycol) was observed to increase with increasing the externally applied uniform dc magnetic field. Slowly sweeping the magnetic field between 0 and 3.1 T results in a frequency-field response curve. Chemical doping was done by exposing the polyaniline-emeraldine base film to HCl vapor. The change in population of free spins is reflected in increased frequency-field curve magnitude after HCl doping. Two working hypotheses explaining this observation are offered to explain how frequency of QCM with deposited magnetic film shifts with increasing intensity of the magnetic field.     

Adsorption of fatty acids from alkane solution studied with quartz crystal microbalance

This paper describes the adsorption of the unsaturated fatty acids, oleic-, linoleic-, and linolenic acid onto steel coated quartz crystal surfaces from 2,2,4,4,6,8,8-heptamethylnonane as monitored by the quartz crystal microbalance (QCM) technique. It is shown that addition of fatty acid to the oil results in changes in bulk density and viscosity and that these changes must be considered before the sensed mass can be evaluated. The change in viscosity of the solution is larger for oleic acid than for linoleic acid and linolenic acid, which results in a larger correction for oleic acid with respect to bulk effects. After considering the effects due to changes in bulk properties, the influence of the viscoelastic properties of the adsorbed layer on the sensed mass was evaluated. The correction for the viscoelastic properties of the adsorbed layer was found to be very small for the systems studied. The sensed mass, at 1.1 weight percent, ranged from 0.5 mg/m² for oleic acid to 5 mg/m² for linolenic acid.     

Ethanol sensing properties of PVP electrospun membranes studied by quartz crystal microbalance

In this study, ethanol gas sensing of PVP fiber membranes based on Quartz Crystal Microbalance (QCM) was investigated. The fibers were deposited on the QCM’s electrodes by electrospinning the viscous blend solutions of PVP. The effects of PVP concentration on morphology of the fibers and their permeability when exposed to ethanol were investigated. Membranes which were prepared using low concentration solutions, contained beads and high packing fibers and showed low permeability. Increase of the PVP concentration to 12 wt% resulted in continuous fine fibers with good permeability. Furthermore, higher PVP concentrations were found to decrease ethanol permeability due to larger fiber radius and lower surface area. Moreover, effects of fibrous layer thickness on gas response was examined. Consequently, optimum amount of PVP concentration and fibrous layer thickness for the best gas response was found.     

A low-temperature quartz microbalance

The design of a low-temperature quartz microbalance based on standard radio engineering quartz resonators is described. The sensitivity of the balance on PK88CP, PK104-5M, and PΓ-07 resonators at a 5-K temperature is determined. Special features of the practical use of the microbalance in the FTIR matrix insulation spectroscopy are considered. It is shown that, for films of solidified inert gases, one may ignore the dependence of the sensitivity on the frequency shift below 0.5–1.0% of the initial frequency of the resonator. Original Russian Text ? A.Yu. Ivanov, A.M. Plokhotnichenko, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 166–169.     

On the current status of quartz crystal microbalance studies of superconductivity-dependent sliding friction

Recent observations of superconductivity-dependent friction in nitrogen films adsorbed on lead substrates have inspired a number of theoretical and experimental efforts to understand the origins of this phenomenon. The status of these efforts is discussed, focussing on the role of electronic contributions to friction.     

A combined reflectometry and quartz crystal microbalance with dissipation setup for surface interaction studies

We have developed an instrument for surface interaction studies, which combines a newly invented four detector optical reflectometry setup with quartz crystal microbalance with dissipation (QCM-D) monitoring. The design is such that data from both techniques can be obtained simultaneously on the same sensor surface, with the same signal-to-noise ratio and time resolution, as for the individual techniques. In addition, synchronized information about structural transformations, molecular mass, and the hydration of thin films on solid surfaces can be obtained on the same specimen, as validated by monitoring the formation of supported lipid bilayers on a silica-coated QCM sensor surface. We emphasize that the optical (molecular) mass can be separated from the acoustic mass including hydrodynamically coupled solvent, which means, in turn, that the amount of solvent sensed by the QCM-D technique can be dynamically resolved during adsorption processes. In addition, the advantage/necessity to use four, compared to two, detector reflectometry is emphasized.     

Rapid determination of volatile organics using a nanoporous zinc oxide microsphere-coated quartz crystal microbalance

The organic vapor sensing properties of nanoporous ZnO microspheres coated on a quartz crystal microbalance were characterized. The ZnO nanoparticles were aggregated by aqueous synthesis into micrometer diameter spheres. The porous structure of the microspheres provided sufficient surface area for vapor adsorption and diffusion for gas exchange. The reversible response suggests that complete desorption without contamination was achieved. Sensing films on a quartz crystal microbalance (QCM) were characterized using five volatile organic compounds with different functional groups to compare the differences in selectivity between polyisobutylene (PIB) and nanoporous ZnO. The response time for nanoporous ZnO was half the value of the PIB-coated sensor. The results show that nanoporous ZnO microspheres are an alternative that provide selectivity and rapid response for QCM.