Integrated surface acoustic wave wireless temperature sensor

Abstract

The invention relates to an integrated surface acoustic wave (SAW) wireless temperature sensor, comprising an interdigital transducer with an EWC / SPUDT structure and 11 reflectors with short-circuit gate structures, which are manufactured on a piezoelectric substrate, wherein, the EWC / SPUDT receives an electromagnetic wave signal transmitted from a wireless reading unit by a wireless antenna and transforms the signal into surface acoustic wave which is propagated along the reflectors on the surface of the piezoelectric substrate and is respectively reflected by the reflectors, the reflected acoustic wave is retransformed into the electromagnetic wave signal by an EWC / SPUDT2, the signal is returned to the wireless reading unit by the wireless antenna, and finally temperature detection is realized by evaluation on a phase change of time-domain response via a signal processing method. In the sensor, the 11 reflectors of a SAW reflection delay line are divided into two paths for reducing multiple reflection among the reflectors, wherein, 8 reflectors on one path are used for 8-bit electronic tags, and 3 reflectors on the other path are used for temperature detection; and a reflection peak of a time domain S11 with even response is obtained by adjusting electrode number of the reflectors.

Description

technical field [0001] The invention relates to a surface acoustic wave (SAW) temperature sensor integrated with an electronic label, in particular to a SAW reflective delay using a single-phase unidirectional transducer with a controlled electrode width and a short-circuit grid reflector structure line of wireless temperature sensors. Background technique [0002] The propagation speed of SAW has a linear relationship with temperature, that is, Δv=v 0 ×TCD×(T-T ref ), where TCD is the first-order delay temperature coefficient of the piezoelectric substrate (depending on the crystal structure and tangential direction of the piezoelectric substrate material), Δv is the velocity change, and v 0 is the SAW speed, T ref as the reference temperature. In this way, some piezoelectric substrates such as LiNbO with higher temperature coefficient, that is, high TCD value, are used 3 , LiTaO 3 and La 3 Ga 5 SiO 4 Can realize the detection of temperature. In recent years, with...

AI Technical Summary

Problems solved by technology

The interdigitated reflector has a large reflection coefficient, so it can better improve the device loss and signal-to-noise ratio, but due to the reflection between the interdigitated electrodes and the acoustic-electric regeneration, it causes large time-domain noise

The single-finger reflector can reduce the time domain noise of the device, but the small reflection coefficient leads to large device loss and low signal-to-noise ratio

[0007] 3. Due to the attenuation of sound wave propagation, usually the long propagation path of the delay line leads to poor uniformity of the reflection peaks from each reflector. The farther away from the transducer, the greater the loss and the lower the signal-to-noise ratio, which directly affects the time domain Extraction of time-delayed signals

[0008] 4. At present, an important development trend of the sensor system is the integration of functions, which is conducive to the real-time detection of multiple parameters, and is also conducive to the realization of system miniaturization and portability; and the existing wireless sensors using SAW reflective delay lines The temperature sensor has a single function; therefore, it directly hinders some performance improvements and practical applications of SAW wireless temperature sensors

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