Development Of High-sensitivity Sensors Research Articles

Thickness shear SMR resonator based on Yttrium-doped AlN for high sensitive liquid sensors

AlN doped with transition metals becomes the key for high performance acoustic wave devices due to its improved piezoelectricity after the incorporation of dopants. In this paper, solidly mounted resonator (SMR) based on Yttrium (Y) doped AlN and operates in thickness shear (TS) mode is numerically studied for liquids characterization. The modeling of the TS-SMR is done by finite element analysis and the results are compared to experimental data for validation. After that, the effect of Y concentrations on the acoustic displacement profiles, the resonance frequency and the admittance of the SMR is investigated. The sensitivity of the TS mode resonator to liquids mass loading, viscosity and conductivity is studied for different Y concentrations and different glycerol-in-water contents. The obtained results show that doping AlN with Y enhances the electromechanical and liquids sensing capabilities of TS-SMR and contributes in the development of high sensitive sensors for liquids characterization.

Excitation and detection of evanescent acoustic waves in piezoelectric plates: Theoretical and 2D FEM modeling

This paper presents the results of the theoretical and 2D FEM modeling excitation and detection of evanescent acoustic waves in piezoelectric plates. By application of 2D ordinary differential equations derived by Auld, we obtained the dispersion curves of A1 and SH1 waves in YX LiNbO3 and YX KNbO3 plates in proximity to a zero group velocity point. The branches corresponding to evanescent acoustic waves are distinguished. A frequency range where real part of evanescent wave velocity is more than imaginary one was found. In this region evanescent mode is characterized by opposite directions of the phase and group velocities, i.e. this is backward wave. The theoretical analysis was verified in commercial 2D FEM software COMSOL 5.3. By modeling a set of interdigital transducers placed on the surface of Y-cut LiNbO3 wafer with various values of the spatial period we found the resonant frequencies corresponding to evanescent A1 mode. Due to proximity of this wave to a zero group velocity point its properties should be extremely sensitive to change of waveguide quality and ambient air. This is open the possibility to use these waves for development of high sensitive sensors and for nondestructive waveguide analysis.

The effect on cross-polarization conversion by the end shape of electric split-ring resonators in a multilayer metamaterial device

Several types of multilayer metamaterial devices are studied to achieve cross-polarization conversion as well as subwavelength transmission enhancement. The surface current of three metamaterial layers reveals that the induced current around the apertures of the middle metal layer is the key to the physical mechanism. Furthermore, the simulated results show that the proposed devices have good performance on both the polarization conversion ratio and transmission rate. Lastly, a tunable cross-polarization conversion design is proposed and researched. These results can help to facilitate the development of high-sensitivity sensors and terahertz technology.

Surface plasmon resonance biosensors for environmental analysis: general aspects and applications

Interest in the development of Surface Plasmon Resonance (SPR) based biosensors for the detection and monitoring of analytes in several fields has been extensively developed in the last decade. Indeed, SPR-based biosensors demonstrate interesting potential for environmental applications, and a substantial number of studies have been reported for heavy metals, dioxins, pesticides, aromatic hydrocarbons, phenol, polychlorinated biphenyls and detection. This paper reviews the current state-of-art in SPR sensors and outlines important issues with regard to the development of high-sensitivity sensors, in particular for the detection of small biomolecules. Furthermore, the future prospects for SPR sensor technology, such as low cost of production, compact design, reusability and increased functionality (multiple analytes detection), are discussed.