Temperature Dependence of Normalized Sensitivity of Love Wave Sensor of Unidirectional Carbon Fiber Epoxy Composite on Mn-Doped 0.24PIN-0.46PMN-0.30PT Single Crystal Substrate

Naixing Huang,Tianquan Lü,Jian Liu,Wenwu Cao,Bin Yang,Enwei Sun,Lianfu Han,Rui Zhang

doi:10.3390/app10238442

Abstract

Love wave sensors have attracted significant interest due to their high sensitivity and low attenuation. Love mode acoustic dispersion relation, highest normalized mass sensitivity, optimum normalized waveguide layer thickness, and temperature coefficients of frequency (TCF) were theoretically studied for the carbon fiber epoxy composites (CFEC)/Mn:0.24PIN-0.46PMN-0.30PT structure sensor. The highest normalized mass sensitivity exhibits a decreasing trend as the temperature increases from 25 °C to 55 °C. TCF can be improved by increasing the normalized layer thickness (h/λ); however, the temperature dependence of normalized mass sensitivity decreases. For the carbon fibers (CFs) in the CFEC waveguide along the propagation direction of Love wave, the device has a relatively small TCF of −10.92 ppm/°C at h/λ = 0.4001, where the normalized mass sensitivity is approximately 1.5 times that of a typical fused quartz/ST-quartz configuration device. The theoretical results imply that good temperature stability and high measurement precision were obtained from the device in the system CFEC/Mn:0.24PIN-0.46PMN-0.30PT with the CFs in the CFEC along the propagation direction of Love wave (x-axis). The ideal waveguide material requires a small elastic constant c44; however, the ideal piezoelectric substrate requires large elastic constants c44E and c66E.

Highlights

Love wave sensors are highly sensitive acoustic devices, both in the liquid and gas phases, that can be used in immunoassay formats, detection of organic compounds, gas monitoring, etc. [1,2,3]
Mn:0.24PIN-0.46PMN-0.30PT piezoelectric single crystal, the dispersion curves of the Love mode surface acoustic waves for the carbon fibers (CFs) in the carbon fiber epoxy composites (CFEC) guiding layer along the x- and y-axes at 25 ◦ C are shown in Figure 2a,b, respectively
Different propagation characteristics of the Love waves will result in different performances of the devices with the CFs in the CFEC guiding layer parallel to the x-axis and y-axis

Summary

Introduction

Love wave sensors are highly sensitive acoustic devices, both in the liquid and gas phases, that can be used in immunoassay formats, detection of organic compounds, gas monitoring, etc. [1,2,3]. The temperature coefficient of frequency (TCF) is zero in theory for a SiO2 /LiTaO3 structure device for a normalized layer thickness of 0.255; the sensitivity to mechanical surface perturbations of the structure is only approximately 50% of that of the traditional SiO2 /quartz sensor [5]. Good temperature stability and high electromechanical coupling are generally required for piezoelectric substrate materials used in practical SH-type surface wave device [28]. In a Love wave device, choosing a piezoelectric substrate with a higher electromechanical coupling coefficient can reduce insertion loss [29]. This paper reports on the theoretical characteristics of temperature dependence dependence for for normalized normalized mass mass sensitivity sensitivity and and the the optimum optimum design design of of normalized normalized temperature layer thickness of the CFEC/Mn:PIN-PMN-PT configuration device in the range of.

Theory and Equation

Schematic

Results and Discussion

Dispersion relation of Love waves at 25

Conclusions

Figures and