Remote vibration measurement: A wireless passive surface acoustic wave resonator fast probing strategy

Abstract

Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/π periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

Near-field interrogation of SAW resonators on rotating machinery

“…For the last 20 yr, SAW transducers have also been used as wireless sensors in harsh environments such as for temperature measurements as reported in Reindl and Shrena (2004), Friedt et al (2011), Fachberger et al (2006. They have also been used for torque (Beckley et al, 2002;Kalinin and Brown, 2010), strain (Pohl et al, 1999;Friedt et al, 2012), pressure (Reindl et al, 1998;Buff et al, 1997), chemical (Dong et al, 2001;Wang et al, 2009) and moisture level measurements (Kawalec and Pasternak, 2008). Due to the deeper penetration depth of electromagnetic waves at low operating frequency, the interrogation of SAW sensors is mainly focused on the European industrial, scientific and medical (ISM) band centered in 434 MHz whose narrow bandwidth is only compatible with a resonator configuration.…”

High temperature packaging for surface acoustic wave transducers acting as passive wireless sensors

“…The leading coefficient 2 reflects that our reader electronics receiver stage is based on a power detector [21], a quantity related to the returned voltage by a squared function. The signal loss in the resonator acts in a similar way as the radar cross section in the classical radar equation, and the interrogation range is dependent on this loss through a fourth power law [26]. As an application of the observed quality factor variations during sensor heating from room temperature to 220 • C (Fig.…”

Fast contactless vibrating structure characterization using real time field programmable gate array-based digital signal processing: Demonstrations with a passive wireless acoustic delay line probe and vision

“…We have previously described the implementation of a fast measurement algorithm identifying the limitation on the measurement bandwidth when using an acoustic resonator transducer acting as a strain gauge 35 : a practical implementation reaching this refresh rate has been demonstrated by another group in 36 . Comparison of the resonator based measurement and the optical measurement, both of which are performed at 7 ksamples/s, is provided in Fig.…”

“…4. The quantitative analysis of the resonator based strain gauge measurement to generate an estimate of the prong displacement has been provided previously 35 , while the optical periodic pattern image processing analysis directly provides a quantitative estimate of the prong end displacement. Fig.…”