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2003 S&T e-Digest Contents



No. 2, February 2004



Table of Contents




A Flowmeter for Measurements of Very Small Gas Flows


Abstract: : The paper presents description of a flow meter for measurements of very small gas flows (some or several ml/min). Low elementary volumes of gas are counted.  The elementary volumes are generated as gas bubbles located in a liquid. In the applied method of measurement of the bubble volume, a vertical column is subjected to a homogeneous light beam, next a luminous flux is detected by a set of optical wave-guide detectors. Detection enables to find a bubble and determine its dimensions. Finally, signals from the detectors are changed into electric signals in the measuring converters and they are registered in a computer.


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Mariusz R. Rząsa1, Jan Sawicki2

1Department of Thermal Engineering and Industrial Apparatus, Technical University of Opole, Poland

E-mail: mrz@po.opole.pl

2Department of Industry Electronics, Warszawa, Poland

E-mail: pie@pie.edu.pl



An Efficient Piezoelectric Analysis for Quartz Crystal Nanobalance Gas Sensor


Abstract: Based on the conventional metal-oxide-semiconductor-field-effect transistor (MOSFET), a new chemical field-effect transistor (ChemFET) gas-sensing device was fabricated by depositing organic gas-sensing material on the gate area of MOSFET replacing the gate metal. Sandwich-like bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] samarium complex Sm[Pc*]2 (Pc*=Pc(OC8H17)) was used as the gas-sensing material for detecting nitrogen dioxide (NO2). Using Langmuir-Blodgett (LB) technology, Sm[Pc*]2 LB film was prepared and deposited on the gate area forming the gas-sensing film/oxide/semiconductor structure with a sensitive gate area of 50mm50mm. The gas-sensing property and response-recovery property of Sm[Pc*]2 LB film/SiO2/Si structural ChemFET sensor to NO2 gas was studied by the change of drain current (IDS) during gas exposure. The results show that ChemFET gas sensor with Sm[Pc*]2 LB film can detect NO2 gas down to 2.5ppm. And the response and recovery time to 40ppm NO2 gas was about 15 s and 3 min. The mechanism of sensitivity of Sm[Pc*]2 LB film ChemFET to NO2 was also discussed in this paper.


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Der Ho Wu1, Wen Tung Chien1, Yng Jyi Tsai2

1Associate Professor, PhD, 2Graduate student

Microsystems Simulation and Design Lab., Department of Mechanical Engineering,

National Pingtung University of Science and Technology, Taiwan

E-mail: derhowu@mail.npust.edu.tw



Electrophysical Properties of Gas Sensitive Films SnO2 Doped with Palladium


Abstract: Pd-dopant influence (from 0,5 to 3 weight %) on the electrophysical properties and gas sensitivity of SnO2 films, produced by reactive ion-beam sputtering of tin target, was investigated. Doping with palladium was carried out from water salt solution PdCl2. It was found that Pd-dopant (1,5 weight % Pd) has decreased the temperature of maximal gas sensitivity of SnO2 films towards ethanol and acetone up to 200 oC and 250 oC, respectively. Possible mechanisms of Pd influence on the gas sensitivity of SnO2 films were discussed.


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Rembeza S., Rembeza E., Svistova T.

Voronezh State Technical University,Russia

E-mail: rembeza@ftt.vsu.ru



In Situ Monitor the Adsorption of Triton X-100 on Quartz Surface

by an Electrode-Separated Piezoelectric Sensor


Abstract:  In the configuration of an electrode-separated piezoelectric sensor (ESPS), the quartz crystal surface is in a direct contact with the liquid phase. The quartz surface can be hydrated to form silanol groups, which can adsorb nonionic surfactant Triton X-100 through hydrogen-bonding interaction between the silanol OH group and the ether oxygen atoms. The adsorption process of Triton X-100 on quartz crystal surface corresponds to a mass increase and can be monitored in situ by the ESPS device. And the adsorption densities and kinetics parameters can be obtained in the ESPS method. It was shown that the adsorption of Triton X-100 on quartz surface is reversible with respect to the dilution of bulk phase and can be analyzed using Langmuir model. The adsorption density and adsorption equilibrium constant decrease as pH rises. With increasing ionic strength, the adsorption rate constant and equilibrium constant increase slightly.


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Dazhong Shen, Fei Wang, Qi Kang, Duanling Yang

School of Chemistry and Chemical Engineering, Shandong University, P.R. China,

E-mail: dzshen@sdu.edu.cn



Study on the Properties of an Electrochemical Sensor of Modified Methylene Blue

on Vitreous Carbon Electrode


Abstract: This paper described the structure and electrochemical properties of MB adsorption layer on the surface of vitreous carbon electrode. The experimental results showed that the molecules of MB were adsorbed on the surface of vitreous carbon in the form of dimer, and it would dissociated to form a monolayer in special conditions, such as treating the modified electrode in ethanol under ultrasonic or in boiling water. We studied the electrochemical kinetics of adsorbed MB and calculated some physical chemistry parameters to evaluate the electron-transfer efficiency and to understand the mechanism of the electrochemical reaction. It makes clear that the electrochemical reaction is not a purely charge transference controlled procedure and also not a typical semi-infinite diffusion controlled one. It is reasonable because that the protons in solution were the participants in the redox reaction of adsorptive MB meanwhile the electron transfer in surficial layer. Furthermore, the modified electrode was used in the cyclic voltammetric experiment as a sensor of ferriporphyrin. It could proportionally respond the concentration of ferriporphyrin in deoxygenated neutral phosphate buffer.


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Tu Yifeng,

College of Chemistry and Chemical Engineering,

Suzhou University, P.R. China

E-mail: tuyf@suda.edu.cn





Miniature ICP* Accelerometer with Transducer Electronic Data Sheet (TEDS)


Depew, NY - Miniature Model 352A56 ICP TEDS accelerometer from the Vibration Division of PCB Piezotronics, Inc. occupies a small 0.26 x 0.57 x 0.30 inch (6.6 x 14.5 x 7.6 mm) footprint and weighs a mere 0.06 ounces (1.8 grams) for minimal mass loading of the test article. The device is ideally suited for vibration studies and stress screening of miniature components such as circuit boards, disc drive mechanisms, and other electronic items; modal analysis of small structures and satellite components; vibration measurement of scaled models; and biomedical research.


TEDS (Transducer Electronic Data Sheet) accelerometers conform to the IEEE P 1451.4 standard, which defines a mixed-mode interface that retains the traditional analog sensor signal, but adds a low-cost serial digital link to access a TEDS embedded in the sensor for self-identification and self-description. The embedded memory chip eliminates the need to manually input sensor parameters such as manufacturer, model number, serial number, calibration date, and sensitivity when configuring a system.


The ICP unit is structured with a shear mode, piezoceramic sensing ceramic element and built-in signal conditioning microelectronics to produce clean, low-impedance voltage output signals capable of being transmitted over long cable lengths. Measurements from Vi to 10,000 Hz may be accurately measured ( 5%).



Craig S. Aszkler, 

Division Manager

Vibration Division

3425 Walden Avenue, Depew, NY 14043-2495

Phone: (888)684-0013, fax: (716)685-3886

E-mail: caszkler@pcb.com

Accelerometer 352A56



Intrinsically Safe, Piezoelectric Pressure Sensors Satisfy

Dynamic Pressure Measurement Requirements


Depew, NY - The Pressure Division of PCB Piezotronics, Inc., introduces a series of ICP pressure sensors that have been certified under ATEX and CSA (Canada and US) as intrinsically safe for use in hazardous environments.


These dynamic pressure sensors are available in various mounting configurations, such as NPT, English and metric straight threads, with pressure ranges up to 20,000 psi. ICP" sensors incorporate built-in signal conditioning circuitry for ease of use and long distance signal transmission capability. These sensors measure dynamic pressure events such as surges, pulsations, spikes, and are useful for monitoring the performance of compressors, pumps, and gas turbines, as well as detecting flow anomalies in piping systems.


Dan Cummiskey 

Division Manager

Pressure Division

3425 Walden Avenue, Depew.NY 14043-2495

Phone:(888)684-0011, fax: (716)686-9129

E-mail: dcummiskey@pcb.com

Pressure sensor



In-Line Strain Gage Signal Conditioner


Depew, NY -The Force/Torque Division of PCB Piezotronics, Inc., introduces Model 8160A in-line strain gage signal conditioner, which provides regulated, strain gage excitation voltage and delivers both voltage and current mode output signals for recording, control, or analysis purposes.


The Model 8160A is designed for use with strain gage load cells and reaction torque sensors and incorporates easy to use zero and span adjustments via screwdriver adjustable potentiometers. The in-line design makes it a convenient choice for use with PLCs and computer based data acquisition systems.



Peter Munschauer, Division Manager

Force/Torque Division

3425 Walden Avenue

Depew, NY 14043-2495

Tel: (888) 684-0004, fax: (716)684-8877

E-Mail: pmunschauer@pcb.com

Strain gage signal conditioner 8160A



4-20 mA Side Exit Vibration Sensor


Depew, NY - The IMI Division of PCB Piezotronics introduces Model 642, a low profile, two wire, loop-powered, current output side exit sensor with patented 360-degree swivel mount technology. It is able to interface with existing alarm, control, and monitoring systems such as PLC's, DCS's, and SCADA systems. Temperature range is from -40 F to +185 F (-40 C to +85C).


Options include dual-output versions, and built-in temperature sensor. Peak velocity, rms velocity, and rms acceleration versions are available. These sensors withstand exposure to harsh industrial environments and are used for monitoring rotating machinery, gears, bearings, and motors.

Tim Geiger

Division Manager

IMI Sensors Division

3425 Walden Avenue, Depew, NY 14043-2495

Phone: (800) 959-4464, fax: (716)684-3823

E-mail: tgeiger@pcb.com

Vibration sensor



New Torque Sensor Will Revolutionise Machine Control


Sensor Technology will be launching their new RWT-310 and RWT-320 Torqsense Rotary Torque Sensors at the MTEC Exhibition.


The RWT-310 units utilise a non-contact measurement technique, so reduce the previously difficult task of accurate real-time torque monitoring to the simple task of literally mounting the transducer close to the machine drive shaft under investigation. As such they stand to completely redefine the expectation of machine builders and control engineers.


RWT-320 sensors also feature integral electronics with digital and analog outputs for torque, speed and power and are directly compatible with PC Interfaces such as serial and USB, being user programmable for analog signal levels.


Other innovative features include built-in peak torque sampling, storage and torque averaging. They can operate from a wide range of supply voltage.

To achieve the non-contact operation that makes the Torqsense transducer range unique SAW (Surface Acoustic Waves) devices are used as frequency dependent strain gauges to measure the change in resonant frequency caused by strain experienced in the drive shaft. This measurement is directly related to the torque and opens up new horizons for advancing all manner of machine control.


Tony Ingham

Sensor Technology Ltd.

P.O. Box 36, Banbury, Oxon, OX15 6JB

Phone: 01295 730746

E-mail: info@sensors.co.uk


Torque Sensor



Multi-Channel Vibration Analyzer


Provo, UT - Larson Davis is pleased to announce the extension of its Total Customer Satisfaction guarantee to cover the LMS Pimento analyzer manufactured by LMS of Leuven, Belgium. Customers who purchase the Pimento from Larson Davis can feel especially secure in their purchase due to this exceptional guarantee, which promises that "if at any time you are not completely satisfied with the product, Larson Davis will repair, replace or exchange it at no charge." Beyond this, the option of a 100% refund is available to the customer at any time.


LMS Pimento is the personal noise and vibration analyzer for professionals on the move. It can handle most tasks in general data acquisition, rotating machinery, structural analysis, and acoustics, including sound power measurements.


John Carey

Marketing Manager, Acoustic Test Products

Larson Davis, Inc.

1681 West 820 North, Provo, UT 84601


E-mail: Jcarey@larsondavis.com

Vibration Analyzer





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