Abstract
A Love wave-based sensing chip incorporating a supramolecular cryptophane A (CrypA) thin film was proposed for methane gas sensing in this work. The waveguide effect in the structure of SiO2/36° YX LiTaO3 will confine the acoustic wave energy in SiO2 thin-film, which contributes well to improvement of the mass loading sensitivity. The CrypA synthesized from vanillyl alcohol by a double trimerisation method was dropped onto the wave propagation path of the sensing device, and the adsorption to methane gas molecules by supramolecular interactions in CrypA modulates the acoustic wave propagation, and the corresponding frequency shifts were connected as the sensing signal. A theoretical analysis was performed to extract the coupling of modes for sensing devices simulation. Also, the temperature self-compensation of the Love wave devices was also achieved by using reverse polarity of the temperature coefficient in each media in the waveguide structure. The developed CrypA coated Love wave sensing device was connected into the differential oscillation loop, and the corresponding gas sensitive characterization was investigated. High sensitivity, fast response, and excellent temperature stability were successfully achieved.
Highlights
Underground mine methane gas poisoning or explosions can cause huge casualties and property losses
Parameters were extracted for Love wave sensing device simulation prior to fabrication
Was synthesized by a typical two-step method, and coated onto the wave propagation path by using a was synthesized by a typical two-step method, and coated onto the wave propagation path by using dropping method
Summary
Underground mine methane gas poisoning or explosions can cause huge casualties and property losses. Love of wave device for methane gas thin-film sensing was proposed, whichaistemperature-compensated composed of a waveguide structure. A theoretical simulation using FEM analysis was the temperature of coefficient (Tcf) against the 36◦ YX LiTaO3 , lower Tcf of the hybrid Love wave device is expected by varying the SiO2 thickness. Devices the waveguide structure of SiO2 /Al electrodes/36◦ YX LiTaO3 /PML (perfect match layer), as depicted There exists an optimum SiO2 thickness allowing self temperature-compensation and and maximum maximum mass massloading loadingsensitivity sensitivity [17], it can extracted solving coupled [17], andand it can be be extracted by by solving the the coupled electromechanical field equation in layered media. 2 2thickness were by extracted by FEM analysis mentioned as listed in Table
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