Wyniki wyszukiwania - BazTech

1

Surface Acoustic Wave Interaction with a Mixture of Oxygen and Nitrogen

Pasternak Mateusz, Jasek Krzysztof, Grabka Michał, Borowski Tomasz

Archives of Acoustics

|

2020

|

Vol. 45, No. 3

483--486

EN

Parameters of surface acoustic waves (SAW) are very sensible to change of physical conditions of a propagation medium. In the classical theory formulation, the waves are guided along the boundary of semi-infinity solid state and free space. A real situation is more complex and a medium commonly consists of two physical components: a solid substrate and a gaseous or liquid environment. In the case of stress-free substrate, the strongest impact on SAW properties have surface electrical and mechanical conditions determined by solids or liquids adhering to the boundary. This impact is utilised for constructing sensors for different gases and vapours e.g. (Jakubik et al., 2007; Hejczyk et al., 2011; Jasek et al., 2012). The influence of gaseous environment on the SAW properties is usually very weak and ignored. However, in certain condition it can be significant enough to be applied to sensor construction. In general, it concerns Rayleigh wave devices where energy leakage phenomenon is perceptible, especially when the gas being detected considerably changes the density of environment. The paper presents the results of experiments with oxygen-nitrogen mixture. Their primary aim was focused on finding the dependence of resonant frequency and attenuation in SAW resonator on parameters and concentrations of the gas in the environment.

2

A New Nanoporous Material in Chemical Sensor for Vapors of Some Volatile Organic Solvents

Balcerzak A.

Archives of Metallurgy and Materials

|

2009

|

Vol. 54, iss. 4

999-1004

EN

A new material has been proposed as a chemosensitive layer in the surface acoustic wave sensor for vapors of some volatile organic solvents. This material has been fabricated from the bicomponent mixture of 5-[[1,3-dioxo-3-[4-(1-oxooctadecyl) phenyl] propyl] amino]-1,3-benzenedicarboxylic acid and cetylamine. In the Langmuir-Blodgett process a nanolayer of the mixture has been deposited on a piezoelectric substrate with interdigital transducers. Subsequently, the molecules of cetylamine have been removed from the layer leaving nanopores. Sensing properties of this layer for the vapors of some volatile organic solvents in air have been investigated.

PL

Zaproponowano nowy materiał na warstwę chemoczułą czujnika do wykrywania par wybranych lotnych rozpuszczalników organicznych, wykorzystującego akustyczną falę powierzchniową. Materiał ten został wytworzony z dwuskładnikowej mieszaniny kwasu 5-[[1,3-diokso-3-[4-(1-oksooktadecylo) fenylo] propyl] amino]-1,3-benzenodikarboksylowego i cetyloaminy. Osadzono nanowarstwę tej mieszaniny na podłożu piezoelektrycznym z przetwornikami międzypalczastymi stosując proces Langmuira-Blodgett. Następnie cząsteczki cetyloaminy zostały usunięte z warstwy pozostawiajac po sobie nanopory. Zbadano wrażliwość tej warstwy na pary wybranych lotnych rozpuszczalników organicznych w powietrzu.

3

Adsorption properties of porous Langmuir-Blodgett layer used in SAW sensor for vapors of some chlorinated hydrocarbons

Balcerzak A.

Archives of Acoustics

|

2009

|

Vol. 34, No. 3

345-352

EN

The porous Langmuir-Blodgett film has been fabricated from an equimolar mixture of 5-[[1,3-dioxo-3- [4- (1-oxooctadecyl) phenyl] propyl] amino] - 1,3 - benzenedicarboxylic acid (DA) with cetylamine (CA) and subsequently removing of cetylamine after a layer deposition. This film has been investigated as the sensing layer of the surface acoustic waves (SAW) sensor of vapors of some chlorinated hydrocarbons in air. From the experimental results the values of the number of adsorbed molecules of chlorinated hydrocarbons per surface of sensing layer, NM/A, for this porous Langmuir-Blodgett layer has been calculated. An attempt to explain the observed differences in the adsorption of chlorinated hydrocarbons has been undertaken.

4

Surface acoustic wave stress sensors - designing analysis

Filipiak J, Solarz L., Steczko G.

Molecular and Quantum Acoustics

|

2007

|

Vol. 28

71-80

EN

Analysis of viability and application of Surface Acoustic Wave stress sensors (SAW-SSs) to operational safety of buildings and other engineering constructions is the main topic of the paper. SAW stress sensors (SAW-SSs) measure the stress existing on their surface measuring the delay of the SAW signal. The stress in SAW-SS is caused by the measured stress in elements of constructions. The idea of SAW delay lines is described in [1] for example. The information about acting stress is in intermediate frequency of two SAW-SSs working in the SAW generator [3]. This system diminishes influence of the temperature at the measurements. The relatively small intermediate frequency (about 100 kHz) may be easily transmitted at the relatively long distances (about some hundreds m) by concentric cables. SAW-SSs are bound to the linear or surface elements of constructions: beams, frames, plates or shells. Bending moments change the curvature of these elements. The changing curvature of these elements causes the change of strain and stress in the plate of the SAW-SSs. The SAW-SS may also be applied to the measurement of bending instability of rods in truss or lattice constructions. The warning systems signalling overstress or bending instability may be built using SAW-SSs.

5

Analysis of modified surface acoustic wave stress sensors

Filipiak J, Solarz L., Steczko G.

Molecular and Quantum Acoustics

|

2007

|

Vol. 28

81-93

EN

Analysis of designing and application of Surface Acoustic Wave stress sensors (SAW-SSs) to operational safety of buildings and other engineering constructions was the main topic of our previous paper [1]. SAW stress sensors (SAW-SSs) measure the stress existing on the surface of piezoelectric base, measuring the delay of the SAW signal. The stress in SAW-SS is caused by the measured stress in elements of constructions. In this paper the modified SAW-SS is considered. The modified SAW-SSs are bound to the linear or surface elements of constructions indirectly, on supports. This new system diminishes influence of the casings and temperature at the results of measurements. The modified and previously proposed SAW-SSs may be used to measure the stress in bent elements of the construction and may also be applied to the measurement of bending instability of rods in truss or lattice constructions. The monitoring and warning systems signalling overstress or bending instability may be built using SAW-SSs.