A novel wireless passive SAW sensor based on the delay line theory

Abstract

A novel wireless passive SAW temperature and pressure sensor is designed, based on the SAW delay line theory. The effect of the temperature is included in the pressure feedback signal and a weighted factor is introduced in order to separate the temperature effect from the feedback signal. Therefore, the temperature and pressure can be accurately measured at the same time. In this sensor design, the energy converted from IDT is fully used, and the interference between the signals is minimized. The IDT and its reflectors have been optimally designed to improve the sensitivity of the sensor. This wireless passive sensor is capable of working under complicated and hard conditions.

Pressure and Temperature Microsensor Based on Surface Acoustic Wave in TPMS

“…The common solution is to use more than one sensing units to measure pressure and temperature separately, in which case, however, the whole structure of the SAW sensor is complicated for manufacturing and packaging. The preliminary design theory of a novel wireless and passive SAW microsensor, which comprises single sensing unit and is able to measure real-time pressure and temperature accurately was suggested by the authors recently (Li et al, 2008). In this letter, further investigation on this novel sensor is to be reported both in theory analysis and practical test.…”

“…where α is the temperature coefficient of the SAW device substrate, τ 12 is neglected (Li et al, 2008 …”

Pressure and temperature microsensor based on surface acoustic wave

“…Because of their advantages of being wireless and averting the need for a power supply at the sensor location, SAW sensors are able to be used in such moving and harsh conditions as tyre pressure monitoring [5]. In practical applications, such as tyre pressure monitoring systems (TPMS), it is necessary to measure both pressure and temperature simultaneously [5][6][7]. The common solution is to use more than one sensing unit to measure pressure and temperature separately, in which case, however, the whole structure of the SAW sensor is complicated for manufacturing and packaging [5,6].…”

“…The common solution is to use more than one sensing unit to measure pressure and temperature separately, in which case, however, the whole structure of the SAW sensor is complicated for manufacturing and packaging [5,6]. The preliminary design theory of a novel wireless and passive SAW microsensor, which comprises a single sensing unit and is able to measure real-time pressure and temperature accurately, was suggested by the authors recently [7]. In this Letter, further investigation on this novel sensor is reported both in theory analysis and by practical test.…”

“…Since d 13 , which is the difference between d 3 and d 1 in part B, is affected by both DT and pressure, (5) can be set up if the correlation of the effects of DT and pressure on t 13 is neglected [7]:…”