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。     

A conductance sensor for dissolved sulphur dioxide using a series piezoelectric crystal device

A new piezoelectric crystal impedance sensor for the determination of sulphur dioxide in aqueous solution is presented. It is realized using a series piezoelectric crystal device which is constructed by connecting an AT-cut piezoelectric crystal to a probe in series. The probe is filled with an internal electrolyte solution that is separated from sample solutions by a gas-permeable membrane. The present sensor exhibits a favourable frequency response to 1 x 10(-7)-1 x 10(-3) M sulphur dioxide. The detection limit is 1 x 10(-8) M. The effects of the sensor preparation are considered. Dynamic range, reproducibility, response time and selectivity of the sensor are also discussed. The proposed sensor has been used successfully for lamp sulphur determinations in petroleum samples.     

A Simple Sensor for Potentiometric Titrations

Abstract

A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran. The reference was a Ag/AgCl single-junction electrode. The sensor was used in the following potentiometric titrations:

1. precipitation titrations 2. acid-base titrations, 3. compleximetric titrations, and 4. redox titrations.

A survey of its use in such titrations is presented.

Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane.     

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.     

Determination of bioelectrochemical parameters of red cell using a piezoelectric crystal sensor

Based on the impedance behavior of red cell at high frequency, the frequency response of series piezoelectric crystal sensor in the red cell suspension was derived and verified experimentally. A method of using piezoelectric crystal sensor to determine the conductivity of the interior of the cell was proposed. The experimental results show that the mean conductivity of rabbit red cell cytoplasm was 0.269 S/m and the mean shape factor of red cell was 2.05.     

Applications of in situ detection with an auto-mated micro batch analyzer

A new batch-type microscale liquid-phase analyzer, called an automated micro batch analyzer (a.m.b.a.), is introduced. The reaction chamber, a 1500-μl capacity polypropylene microcentrifuge tube, is equipped with conductometric, potentiometric, fluorimetric and spectrophotometric sensors. The sample is loaded into a loop injector and blown into the reaction chamber by compressed gas. Various reagents are delivered to the chamber from pneumatically pressurized reservoirs equipped with inexpensive high-speed valves in the liquid-delivery lines. The valves are under microcomputer control and highly precise microliter aliquots can be delivered by controlling valve on-times. Examples illustrated include acid-base, precipitation and compleximetric titrations with the conductometric sensor; acid-base titrations with the potentiometric sensor; determination of hydrogen peroxide with the fluorimetric sensor; and acid-base titrations, studies of metal/ligand complexation, standrd addition, liquid-liquid extraction and distillation of volatile analytes with the spectrophotometric sensor.     

Experimental setup for the determination of analytes contained in ultrasonically levitated drops

An automated technique for the determination of analytes in an ultrasonically levitated sample of 2 to 5 microL volume has been developed. Contactless dosing of reagents or solvents into an ultrasonically levitated drop was realized via piezoelectric micropumps. Drop size was continually controlled with a programmed CCD camera. A diode array spectrometer designed for the use with optical fibers was used for absorption and fluorescence measurements. Determinations via direct absorption measurements following the method of standard addition and acid-base titrations with an absorption indicator and a fluorescent indicator were carried out. The mean consumption of sodium hydroxide added via a piezoelectric micropump in five successive titrations with 18 nmol of sulfuric acid inside a levitated drop (indicator bromothymol blue) had a relative standard deviation of 0.7% and differed only by 0.2% from the expected value.     

Experimental setup for the determination of analytes contained in ultrasonically levitated drops

An automated technique for the determination of analytes in an ultrasonically levitated sample of 2 to 5 μL volume has been developed. Contactless dosing of reagents or solvents into an ultrasonically levitated drop was realized via piezoelectric micropumps. Drop size was continually controlled with a programmed CCD camera. A diode array spectrometer designed for the use with optical fibers was used for absorption and fluorescence measurements. Determinations via direct absorption measurements following the method of standard addition and acid-base titrations with an absorption indicator and a fluorescent indicator were carried out. The mean consumption of sodium hydroxide added via a piezoelectric micropump in five successive titrations with 18 nmol of sulfuric acid inside a levitated drop (indicator bromothymol blue) had a relative standard deviation of 0.7 % and differed only by 0.2 % from the expected value. Received: 19 January 2000 / Revised: 28 February 2000 / Accepted: 3 March 2000     

Selection of a piezoelectric sensor array for detecting volatile organic substances in water

Sensitive coatings for piezoelectric sensors used to assess the presence of anthropogenic volatile organic substances in the equilibrium gas phase over natural water have been selected using an array of measuring elements, and the data have been processed using principal component analysis. Groups of piezoelectric sensors with similar characteristics for substance identification have been determined based on the correlation between piezoelectric sensor responses when vapors of organic substances were detected. The stepby-step optimization of the piezoelectric sensor array has been carried out in order to identify the greatest number of organic compounds (vapors) in the sample. Volatile organic compounds can be identified in their aqueous solutions and natural water using the optimized piezoelectric sensor array.     

Test method for detecting adulterated apple juice using piezoelectric resonators

The adsorption of a mixture of volatile components comprising the aroma of apple juice was studied using piezoelectric quartz microweighing. Conventional gas-chromatographic adsorbents and specific films of different natures were used to modify the electrodes of a piezoelectric sensor. The conditions of the juice analysis were optimized using a piezoelectric sensor array in the batch mode. Different samples of apple juice and nectar were analyzed under the same conditions using the piezoelectric sensor array. The quality of the samples was estimated by comparing kinetic mass aromagrams. A method was developed for the rapid estimation and assortment identification or the detection of the adulteration of natural and reconstituted apple juice.     

Ratiometric fluorescence anion sensor based on inhibition of excited-state intramolecular proton transfer (ESIPT)

A colorimetric and ratiometric fluorescence anion sensor 1 was designed and synthesized according to site-signalling subunit approach. The sensor exhibited visible color changes from yellow to purple upon addition of the strong basic anions such as acetate. The ratiometric fluorescence changes with significant blue shift about 140 nm were observed during the fluorescence titrations. Such ratiometric fluorescence changes could be due to inhibition of excited-state intramolecular proton transfer (ESIPT). The ¹H NMR titrations indicated that the sensor 1 showed deprotonation in presence of large amounts of acetate ion. Therefore, ESIPT was inhibited owing to presence of deprotonation of phenol unit.     

压电晶体传感器阵列测定装置及数据采集系统

研究了一种利用微机控制测量和采集压电晶体传感器阵列振荡频率的智能型仪器。介绍了其硬件及数据采集软件的功能，结构等。     

A new piezoelectric response model for population growth of bacteria

A piezoelectric response model on the population growth of microorganism is proposed. This model is based on a novel population growth model, which has a more obvious ecological meaning and the fact that the series piezoelectric quartz crystal (SPQC) sensor responses to conductivity changes of the medium during the growth of the microorganism. From the response model four parameters can be obtained including the maximum specific growth rate mu(m), saturated population size N(m), and two constants C and K(1). The influence of the parameters on the response curve is discussed in which the influences of mu(m) and N(m) are more obvious. With the proposed model the quantitative determination of bacteria may be more accurate than the frequency detection time (FDT) method. Then the growth of Escherichia coliform (E. coli) monitored with a SPQC sensor is compared with the simulated growth curve obtained by the proposed model and a good agreement is obtained.     

Polypyrrole-calcion film as a membrane and solid-contact in an indicator electrode for potentiometric titrations

This paper shows the application of conducting polymers (CPs) for constructing potentiometric indicator electrodes. Two types of polypyrrole (PPy)-based calcium sensors are presented, one sensor with PPy-calcion film as the active part and the other sensor with PPy-calcion as a solid-state contact coated with a conventional membrane selective towards calcium ions. It is shown that the PPy-calcion film, due to the complexing properties of calcion ensuring high loading of the film with calcium, is sufficiently selective to be used as the active part or as a mediating layer of the indicator electrode. The electrode, with PPy-calcion film as the active part, was used as the indicator electrode in potentiometric titrations of calcium in mixed solvents, where conventional PVC-based electrode can not be used. For the first time, the practical applicability of PPy-based electrodes in titrations is demonstrated.     

Determination of sulpha-drugs with a piezoelectric sensor

A piezoelectric sensor is used for the determination of sulpha-drugs, as pure substances and in their dosage forms, by an indirect micro method based on reaction of the sulpha-drug with bromine and reduction of the resultant N-bromoderivative with iodide to form iodine, which after extraction is monitored with a piezoelectric quartz sensor. The response of the sensor is linear from 2 x 10(-5) to 4 x 10(-4)M sulpha-drug.     

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

IntroductionRecently,anelectrode-separatedpiezoelectricsensor(ESPS),asanewtypeofchemicalsensors,hasbeenreportedandemployedinchemistryofsolu-tionL1-4J.Inthiskindofpiezoelectricsensors,thehighfrequencyexcitationelec-tricfieldisappliedtothequartzdiskbymeansofaso1utionlayer.Hence,thefrequencyofanESPSismoresensitivetothepermittivityandconductivityofthesolutionthanthatofaclassicalliquidpiezoelectricquartzcrysta1(PQC).TousetheESPSmorereasonably,thetheoryforthiskindofsensorsissti1lrequired'Ino…     

A Rapid Method for Determination of Growth of Thiobacillus Ferrooxidans by Series Piezoelectric Quartz Crystal

ABSTRACT

A rapid and simple method for monitoring the growth of Thiobacillus ferrooxidans is put forward by using a series piezoelectric quartz crystal (SPQC). The SPQC was applied to continuously determine the variation of frequency shift during the culture of Thiobacillus ferrooxidans, with a conductive electrode as the probe. The frequency shift as a function of time agrees with a typical 'S - shape' model, a piezoelectric sensor responding well to the growth of Thiobacillus ferrooxidans. The fundamentals for determination of the bacterial growth activity using the SPQC is also described; the frequency shift is only dependent on the electrical conductivity of the solution and the dielectric constant.     

Titrations with piezoelectric monitoring : Part 1. Fundamental theory and titration of acids and bases

The use of a piezoelectric quartz crystal detector is proposed for monitoring the course of a titration reaction by observation of the frequency shift of the oscillating crystal. Satisfactory titrations can often be obtained using the acid-base technique, which is much more sensitive than the classical conductimetric titration and oscillometric titrration, with a lowest titratable concentration that is much lower but which can still be applied in the presence of a large amount of unreacting electrolyte.     

2-Hydroxy-naphth-1-aldehyde phenyl-thiosemicarbazone: effective thiourea-based sensor for acetate anion

A novel urea-based sensor displaying selective recognition for AcO^? had been designed and synthesized. Experiments showed that sensor 1 can selectively recognize acetate in DMSO. The evaluation of the sensor’s interaction with a variety of structurally different anions was performed by UV–vis titration experiments in DMSO. In addition, the nature of interaction between sensor 1 and AcO^? was investigated by ¹H NMR titrations.     

Studies on biotin–avidin indirect conjugated technology for a piezoelectric DNA sensor

Because of their high sensitivity, piezoelectric sensor techniques are extremely useful for environmental or clinical analysis. We developed a piezoelectric crystal DNA biosensor for the detection of the hybridization reaction based on the self-assembled monolayer technology and biotin–avidin system. 3,3′-Dithiopropionic acid was applied to form a self-assembled monolayer (SAM) on the gold surface of the quartz crystal. Avidin was coated on the gold electrode conjugated with 1-ethyl-3-[3-(dimethylamino)propyl]-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), and then biotinylated nucleotide acids were immobilized on the gold electrode surface through the specific interaction of biotin and avidin. Our results indicated that, using this immobilization method, the piezoelectric DNA sensor shows a higher sensitivity and specificity in detecting the hybridization reaction. The sensor can be used repeatedly by electrode regeneration.