Study on the High Precision Acoustic Measurement Techniques for Determining Temperature Field Around Seafloor Hydrothermal Vent

This paper presents the basis of acoustic method used for temperature field measurement of seafloor hydrothermal vent and two techniques of the parabolic interpolation and the bending compensation of propagation paths of acoustic signal are introduced. Experimental research is performed to exactly rebuild the temperature field around hot springs on the floor of Qiezishan Lake, Yunnan, China. The accuracy of the travel time estimation has been improved based on the aforementioned technique and method. At the same time, by comparison of the results of temperature field with different means, the max absolute error, the maximum relative error and the root mean square error are given. It shows that the technique and the method presented in the paper can be applied to the temperature field measurement detector around the seafloor hydrothermal vent. It also has a good accuracy.

AlN-based surface acoustic wave resonators on platinum bottom electrodes for high-temperature sensing applications

Surface acoustic wave（SAW） resonators with Pt/AlN/Si and Pt/AlN/Pt/Si configurations were fabricated by lift-off photolithography techniques. High-temperature performances of both configurations were investigated for temperature sensor applications. AlN films grown on Ptcoated Si substrates exhibit a lower（002） preferred orientation than those grown on Si substrates. The center frequencies of Pt/AlN/Si and Pt/AlN/Pt/Si configurations at room temperature are 424.1 and 456.4 MHz, respectively.The SAW was limited by Pt bottom electrodes to propagate in AlN layer. The temperature coefficient of frequency（TCF） values of Pt/AlN/Si and Pt/AlN/Pt/Si configurations are-51.6 × 10^-6 and-69.2 × 10^-6℃^-1, respectively.Compared with that of Pt/AlN/Si configuration, the TCF value of Pt/AlN/Pt/Si configuration decreases by 34.1 %.AlN resonator with the Pt floating bottom electrodes provides a large, quasi-constant temperature sensitivity which is suitable for temperature sensor applications.

Development of a surface acoustic wave wireless and passive temperature sensor incorporating reflective delay line

based on optimal design on the core element of the sensor,a wireless and passive surface acoustic wave（SAW）temperature sensor integrated with ID Tag was presented.A reflective delay line,which consists of a transducer and eight reflectors on YZ LiNbO3 substrate.Was fabricated as the sensor element,in which,three reflectors were used for temperature sensing,and the other five were for the ID Tag using phase encoding.Single phase unidirectional transducers（SPUDTs）and shorted grating were used to structure the sAW device,leading to excellent signal to noise ratio（SNR）.The performance of the SAW device was simulated by the coupling of modes（COM）prior to fabrication.Using the network analyzer,the response in time domain of the fabricated 434 MHz SAW sensor was characterized,the measured S11 agrees well with the simulated one,sharp reflection peaks,high signal/noise,and low spurious noise between the reflection peaks were observed.Using the radar system based on FSCW as the reader unit.the developed SAW temperature sensors were evaluated wirelessly.Excellent1 inearity and good resolution of士1℃ were observed.