The surface waves acoustoelectronic sensors based on films of Heusler alloy

Yuri A. Kuzavko 

The Polesie Agrarian Ecological Institute of the National Academy of Science of Belarus (PAEI), Brest 224000, Belarus

Abstract

The surface acoustic waves (SAW) are founded to be curiously at mass loading (~1 ng/sm2) of surface of solid waveguide. We have been used in our investigations the acoustoelectronic filters of 35 MHz on SAW consisted of a planar transducers for SAW generation and receiving at monocrystal high-Q-factor piezoelectric plates of LiNbO3 (X-cut) with sizes of 10x2 mm. It is rendered on sensor substance of ferromagnetic Heysler Ni2+x+yMn1-xGa1-y films with shape memory, thus allowing to realize the so-called 'electronic nose' and 'electronic clapper' at known sensors. The elastic deformation can be achieved at this alloys with the magnitude of several percent by changing temperature, pressure or magnetic field. Ferromagnetic films of Heusler alloys are showing phase transitions at lower temperature, pressure and magnetic field in comparison with volumetric specimen. The passing of electric current through metallic field restores the function of a sensor. That arrangement presents the frequency etalon where it would be inserted at inverted positive relation of apmplifier supplied the generation of narrow line of frequencies. The external loading of active sensor surface would cause the shift of its resonance frequency thus allowing to perform the analysis of air and liquids for containing  toxic and inflammable components. There are many types of SAW and its modes (such as Reyleigh, Love, Lemb, Gulyaev-Bleustein waves, SH-modes, etc.), and some of them are sensitive to mas loading independently. The active smart material increases the sensitivity and reversibility of a sensor. The theoretical calculations are for spreading the Rayleigh and Love waves in Ni2MnGa-LiNbO3(AsGa) structures. It was investigated experimentally on processes of evaporation of liquid drops and the registration of percent concentration of methane in air, the dynamics of bacterium colony in feeding medium with simultaneous digital photographic registration.

 

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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium C, by Yuri A. Kuzavko
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-30 22:35
Revised:   2009-06-07 00:48