An Unexpected Frequency Response of A Piezoelectric Quartz Crystal Sensor to the Density and Viscosity of the Liquid

An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (?f ) show a wave-shape response to liquid density (ρ) and viscosity (η) in fine structure, if the longitudinal wave effect was not eliminated. This result is different from the well-known linear relationship between of ?f and (ρη)1/2. An oscillating frequency-temperature curve of the sensor was observed and explained.

High sensitive piezoelectric quartz crystal liquid density sensor

We report for the first time a cleavage phenomenon in the resonant peak of a piezoelectric quartz crystal(PQC) in liquid phase.In the presence of a strong longitudinal wave effect,an additional resonant peak appears in the conductance-frequency curve.With gradually increasing liquid density,the additional peak moves from low to high frequency region then disappears.The frequency of the additional resonant peak is sensitive to the change in liquid density.The frequency shift of the additional peak is linear with the liquid density in a given range.For a 5 MHz PQC with a reflection distance of 16 mm for longitudinal wave,the sensitivity to liquid density is 2.61×10^6 Hz g^-1 cm^3.The overlap between the primary resonant peak and the additional resonant peak causes a decrease in the intensity of the former and an increase in the intensity of the latter.In a combined impedance analysis method,the changes in surface mass loading,density and viscosity of the liquid were monitored simultaneously by a PQC sensor.

Oscillation Conditions for An Electrode-separated Piezoelectric Sensor in Electrolyte Solution

Based on the needs of the oscillation equation and frequency stability, three oscillation conditions are proposed and have been experimentally verified for an electrode-separated piezoelectric sensor (ESPS ) in electrolyte solutions. The present paper covers the dependence of the minimum cell constant needed for the ESPS on solution conductivity. The oscillation conditions of the classical liquid piezoelectric sensor are discussed. The 'cease-to-oscillate' frequencies of the ESPS were measured.

Simultaneous Multimode Oscillation of Stress-Compensated Cut Quartz Resonator with Narrow-Band Wide Variable-Range Quartz Crystal Oscillator

A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.

Vibration analysis of a new polymer quartz piezoelectric crystal sensor for detecting characteristic materials of volatility liquid

We present a new polymer quartz piezoelectric crystal sensor that takes a quartz piezoelectric crystal as the basal material and a nanometer nonmetallic polymer thin film as the surface coating based on the principle of quartz crystal microbalance(QCM). The new sensor can be used to detect the characteristic materials of a volatile liquid. A mechanical model of the new sensor was built, whose structure was a thin circle plate composing of polytef/quartz piezoelectric/polytef. The mechanical model had a diameter of 8 mm and a thickness of 170 μm. The vibration state of the model was simulated by software ANSYS after the physical parameters and the boundary condition of the new sensor were set. According to the results of experiments, we set up a frequency range from 9.995850 MHz to 9.997225 MHz, 17 kinds of frequencies and modes of vibration were obtained within this range. We found a special frequency fspof 9.996358 MHz. When the resonant frequency of the new sensor's mechanical model reached the special frequency, a special phenomenon occurred. In this case, the amplitude of the center point O on the mechanical model reached the maximum value. At the same time, the minimum absolute difference between the simulated frequency based on the ANSYS software and the experimental measured stable frequency was reached. The research showed that the design of the new polymer quartz piezoelectric crystal sensor perfectly conforms to the principle of QCM. A special frequency value fspwas found and subsequently became one of the most important parameters in the new sensor design.

An Oscillation Condition for an Electrode－separated Piezoelectric Sensor in Non－electrolyte Liquid

n oscillation condition was proposed and experimentally verified for an elec-troderaeparated piezoelectric sensor (ESPS) in non-electrolyte liquid, it was ex-pressed as , where C_s is the solution capaci-tance , R_q, C_o and w are the motional resistance , static capacitance and resonant an-gle frequency of the crystal , respectively. And Y-tgθ, where θ is the phase shift inthe oscillator. The relationships between the minimum cell constant needed for ES-PS to oscillate and each of the following parameters, permittivity, density and vis-cosity of the liquid as well as the oscillator phase shift were discussed. The″ cease-to-oscillate″ frequency of ESPS was measured. The oscillation ability of ESPS in-creases with increasing permittivity or decreasing density and viscosity of the liq-uid. An oscillator with a larger Y value is helpful to drive ESPS.

Frequency characteristic of series piezoelectric sensor and application to the determination of water in organic solvents

Theoretical consideration was proposed for the frequency response of a series piezoelectric sensor to the properties of liquid and verified experimentally. This kind of sensor has sensitive and selective frequency response to the permittivity and specific conductivity of solution with excellent stability, and was applied to the determination of micro-content of water in organic solvents. The detection limit is 0.01 g/L in dioxane.

QCM传感器在生物医学检测中的应用研究进展

现代医学在治疗技术和药物研发不断提升的同时,也越来越依赖于医学检测技术的进步。石英晶体微天平(quartz crystal microbalance,QCM)是基于石英晶体压电效应的一种新型高灵敏的纳克级质量型传感技术,具有实时监测、高灵敏度、免标记等优势,近年在生物医学检测领域中广泛应用。该文概述了近年来QCM传感器的构建及其在核酸、蛋白质、癌细胞和微生物检测中的应用研究进展,并对其未来的发展方向进行探讨。

压电力传感器中晶轴偏转产生的维间耦合研究

针对压电式石英力传感器的维间耦合现象,从敏感材料测量原理出发开展研究。结合优化算法,以控制维间耦合为目标,建立了石英晶轴偏转与传感器维间耦合的公式关系,计算了石英晶轴偏转角度的容差范围,并通过有限元仿真验证了公式精度。结果表明,晶轴偏转对传感器维间耦合影响较大,建立的公式在一定范围内可较高精度地计算维间耦合输出,为高精度压电传感器的研究提供了参考。

双幅正弦波激励频移法的压电石英传感器用于测定凝血时间

快速凝血检测技术在医学诊断领域具有重要应用价值,为了降低样本加入过程的扰动,文章开发了一种双幅激励的压电石英体新型凝血监测系统。该系统采用两种振幅正弦波分别对压电石英体进行激励,通过快速扫频技术测得其在不同激励电压下的谐振频率,所获得的频率差作为测量信号与液体粘度存在良好的线性关系。在血液凝固过程中,介质粘度会发生显著变化,压电石英体双幅频移信号可实现对血液凝固过程的实时动态监测。采用直径8 mm(电极直径3 mm)、基频10 MHz小型镀钛石英晶体设计出一次性微流控PQC检测片,成功用于微滴(15μL)毛细自动进样凝血过程的监测。对比传统单振幅激励PQC血凝监测系统,压电石英体双幅频移监测系统具有灵敏度高、重现性好的优势。使用该系统与商用电化学凝血仪分别对血样凝血时间进行了检测,结果显示两者数据具有很好的相关性。

压电晶体传感器的研究进展

本文简要介绍了压电晶体传感器的基本原理 ,以及基于质量、粘度、电导率变化的溶液分析法。重点介绍了电化学石英晶体微天平 (EQCM)、压电生物传感器 ;对具有很大发展潜力和重要应用价值的串联式压电传感器 (SPQC)、串联式表面声波电导传感器 (SAW)、液隔电极式压电传感器 (ESPS)等也作了简要说明。

压电石英晶体传感器液相检测的影响因素

目的 探讨压电石英晶体传感器液相检测的影响因素。方法 采用AT切向镀金膜的石英晶体制成 2× 5型石英晶体微阵列 ,观察晶体振荡频率在不同粘度和密度的甘油PBS( 0 .15mol LpH 7.0 )溶液、不同浓度的NaCl溶液、不同pH的PB溶液( 0 .0 6 7mol L)及不同体积的PBS溶液 ( 0 .15mol LpH 7.0 )中的变化规律以及机械冲击和重新加样对晶体振荡频率的影响。结果 石英晶体振荡频率随溶液粘度和密度、离子浓度、pH的增大而降低。溶液体积、机械冲击和重新加样对晶体频率基本无影响。结论 石英晶体传感器所处溶液体系的性状如粘度、密度、离子浓度、pH等因素对其振荡频率有较大的影响 。

压电石英晶体传感器检测血浆凝血酶原时间及其初步应用

目的 建立一种压电石英晶体传感器检测血浆凝血酶原时间 (PT)的方法。方法 采用AT切向、基频 1 0MHz的银膜石英晶体作为压电元件 ;观察血浆凝集过程中晶体振荡频率的变化 ,确定血浆凝集反应的起点和终点。结果 ①血浆标本加入反应体系后 ,晶体振荡频率呈阶梯状快速下降 ,接着频率瞬时上升 ,然后再缓慢降低达到平稳 ,频率阶梯下降的起点为血浆凝集反应的起点 ,频率从快速上升变为下降的转折点为血浆凝集的终点 ,计算两点之间的时间即为血浆凝血酶原时间。②该方法的检测结果与STAGO磁珠检测法的相关性好 (γ =0 .97) ,批内CV =0 .78% ,批间CV =2 .3 8%。结论 压电石英晶体传感器检测血浆凝血酶原时间 ,血浆凝集反应起点和终点确定方便、可靠。且操作简单、快速、成本低廉 ,检测结果准确 ,是一种敏感性高、重复性好的血浆凝血酶原时间检测新方法 。

压电石英晶体活化部分凝血酶时间检测传感器的构建及初步应用

目的 建立一种检测血浆活化部分凝血酶时间 (APTT)的压电石英晶体传感器。方法 采用AT切向、基频 1 0MHz的银膜石英晶体作为压电元件 ;观察血浆凝集过程中晶体振荡频率的变化 ,确定血浆凝集反应的起点和终点。结果 (1 )血浆标本加入反应体系后 ,晶体振荡频率呈阶梯状快速下降 ,接着频率瞬时上升 ,然后再缓慢降低达到平稳 ,频率阶梯下降的起点为血浆凝集反应的起点 ,频率从快速上升变为下降的转折点为血浆凝集的终点 ,计算两点之间的时间即为血浆活化部分凝血酶时间。(2 )该方法检测结果与STAGO磁珠检测法的相关性好 (γ =0 .972 ) ,批内CV =2 .5 4 % ,批间CV =7.1 4 %。结论 压电石英晶体传感器检测血浆活化部分凝血酶时间 ,血浆凝集反应起点和终点确定方便、可靠。且操作简单、快速、成本低廉 ,检测结果准确 ,是一种敏感性高、重复性好的血浆活化部分凝血酶时间检测新方法 ,可用于临床常规检测。

多次压电效应对压电力传感器静态特性的影响

采用两片由压电系数d11转换的xy切型压电石英晶片构成单元晶组,研究了多次压电效应对压电传感器的影响,通过与传感器并联电容的方法使其不发生多次压电效应,得出了多次压电效应对传感器静态灵敏度的影响,实验结果表明,在0.1μF的并联电容下,传感器的灵敏度从4.00 pC/N增大到4.07 pC/N,提高了1.75%,进一步分析表明,传感器灵敏度发生变化的实质是多次压电效应影响了压电系数,同时探讨了灵敏度提高后多次压电效应对弹性系数以及传感器刚度和固有频率的影响。多次压电效应的研究为压电类传感器性能的提高提供了一种新方法。

压电基因传感器检测巨细胞病毒PCR产物的实验研究

目的 应用自行研制的压电基因传感器检测巨细胞病毒临床标本的PCR产物 ,探讨压电传感器检测核酸反应的可行性以及各种影响因素。方法 设计特异性DNA探针巯基法固定于传感器晶振表面并调节谐振频率在液相中稳定性达到± 1Hz ,定量加入 65份巨细胞病毒临床标本的PCR产物并观察核酸反应导致的频率变化情况 ,并与PCR产物的电泳结果作对照。结果 加入HCMVPCR阳性产物的传感器谐振频率明显下降 ,3 8例阳性产物的平均频率下降值为73 66Hz ,阴性产物的频率没有变化。与PCR电泳结果的阳性符合率为 86 8%,阴性符合率为 93 10 %。

间苯二酚杯[4]芳烃为涂层的压电石英传感器测定液相多巴胺

研究了以间苯二酚杯 [4 ]芳烃为敏感涂层的石英压电晶体 (PQC)传感器 ,在中性磷酸盐缓冲液体系中对神经传递质多巴胺和抗坏血酸的响应 ,发现间苯二酚杯 [4 ]芳烃对多巴胺有很好的响应选择性 ,这归因于间苯二酚杯 [4 ]芳烃与多巴胺分子结构相匹配 ,形成主客体超分子体系 .以间苯二酚杯 [4 ]芳烃为涂层的PQC传感器对液相中多巴胺具有响应快、重现性好、灵敏度高的特点 ,线性响应范围为 3.5～ 5 0 0 μg

压电液相化学分析

压电液相分析方法有吸附、电解沉积、频移滴定，化学频移、萃取频移、介电分析、内电解、选择性络合、催化、化学倍增、氧瓶燃烧测频、多元混合物速测等法，可用于无机物、有机物、药物、环境、冶金、食品和饮料等分析。

分子印记聚合物压电模拟生物传感器测定烟草中的绿原酸

为快速准确测定烟草中的绿原酸,基于压电石英晶体传感器灵敏的响应性能,结合分子印记聚合物的特异识别性能,研制出绿原酸分子印记压电体声波模拟生物传感器,还探讨了膜的修饰作用,验证了该传感器的印记效应,优化了实验条件。该法线性范围为5.0×10-8～1.0×10-4mol/L,回收率为96.7%～105.0%,RSD为3.7%,并用该法测定了一些烟草中的绿原酸含量。

压电石英晶体传感器检测血浆纤维蛋白原方法的研究及应用

目的 建立一种压电石英晶体传感器检测血浆纤维蛋白原 (Fib)的方法。方法 采用AT切向、基频 1 0MHz的银膜石英晶体作为压电元件 ;观察血浆凝集过程中晶体振荡频率的变化 ,确定血浆凝集反应的起点和终点。结果 (1 )检测池加入凝血酶原待频率稳定后 ,血浆标本加入反应体系后 ,晶体振荡快速下降 ,由于反应中形成的纤维蛋白原凝块的质量、体积与晶体接触的面积以及血清产生的量不同 ,造成频率瞬时的上升、下降 ,或频率稳定 ,直至反应结束频率平稳 ,加样后频率下降的起点为血浆凝集反应的起点 ,频率上升、下降 ,稳定的起始点为反应的终点 ,计算两点的时间即为反应时间 ,查标准曲线得纤维蛋白原的含量。(2 )该方法的检测结果与STAGO磁珠检测法的相关性好 (r =0 .95 7)。结论 压电石英晶体传感器检测血浆纤维蛋白原是一种实时在线检测的方法 ,在线观测凝集反应的终点 ,反应的起点和终点的判别方便、可靠、准确。且操作简单 ,快速 ,成本低廉 ,是一种敏感性高、重复性好的方法 。