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Surface Acoustic Wave Resonator Chip Setup for the Elimination of Interfering Conductivity Responses

Rapp, Bastian E.; Voigt, Achim 1; Dirschka, Marian 1; Rapp, Michael 1; Länge, Kerstin 1
1 Institut für Mikrostrukturtechnik (IMT), Karlsruher Institut für Technologie (KIT)

Abstract (englisch):

A surface acoustic wave (SAW) resonator chip setup is presented that eliminates interfering signal responses caused by changes in the electrical environment of the surrounding media. When using a two-port resonator, applying electrically shielding layers between the interdigital transducers (IDTs) can be challenging due to the limited dimensions. Therefore, a layered setup consisting of an insulating polymer layer and a conductive gold layer was preferred. The SAW resonators were provided with polycarbonate housings, resulting in SAW resonator chips. This setup enables easy application of a wide range of coatings to the active part of the resonator surface, while ensuring subsequent electrical and fluidic integration of the resonator chips into a microfluidic array for measurements. The signal responses of uncoated SAW resonators and those with polymer coatings with and without a gold layer were tested with aqueous potassium chloride (KCl) solutions up to 3 mol/L, corresponding to conductivities up to 308 mS/cm. The use of a polymer coating at the thickness of the first Love mode resonance and a conductive gold layer completely reduced the electrical impact on the SAW resonator signal response, making small signals resulting from changes in viscosity and density of the KCl solutions visible.


Verlagsausgabe §
DOI: 10.5445/IR/1000169775
Veröffentlicht am 08.04.2024
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Mikrostrukturtechnik (IMT)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 05.04.2024
Sprache Englisch
Identifikator ISSN: 2072-666X
KITopen-ID: 1000169775
HGF-Programm 43.35.02 (POF IV, LK 01) Functionality of Soft Matter and Biomolecular Systems
Erschienen in Micromachines
Verlag MDPI
Band 15
Heft 4
Seiten 501
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Schlagwörter surface acoustic wave; two-port resonator; sensor chip; sensor array; liquid sensing; conductivity; parylene C; Love wave; gold
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