Passive wirelessly requestable sensors for magnetic field measurements

Enhanced Sensitivity of FeGa Thin-Film Coated SAW Current Sensor

“…Among the available sensing technologies, the surface acoustic wave (SAW) current sensor features fast response, simple structure, low cost, excellent resistance to interference, low power consumption, and long service life [2][3][4]. Especially, it can realize wireless and passive measurement means to improve system security [5][6][7]. The specialized current sensing prototype employing the magnetoresistance effect was proposed firstly by Reindl et al The obtained current resolution was approximately 5% of full scale (−800 A~800 A) [6].…”

Surface Acoustic Wave Based Magnetic Sensors

“…In the first studies, SAW transponders and GMI wire sensors were combined to form remote devices [14][15][16]. GMI wires were selected for their high sensitivity, and they were bonded to the output IDT of the SAW device, which operated as a reflector, in order to act as load impedance.…”

“…The resonant frequency of the device changes with an external magnetic field. A different idea was put forth by Hauser and Steindl [14][15][16] combining a SAW transducer with a giant magnetoimpedance (GMI) microwire sensor. The GMI sensor has a magnetic sensitivity, at least, one order higher than contemporary giant magnetoresistance (GMR) sensors and can be used to measure very low magnetic fields such as those generated by the human heart or muscles.…”

Analysis of passive surface acoustic wave sensors using coupling of modes theory

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Wireless passive SAW sensors, which are a combination of a SAW device and a classical sensor for detecting physical quantities, have been studied. [10][11][12][13][14][15][16][17][18] Figure 1 shows a passive SAW sensor. An optimum frequency signal transmitted from a transmitter is received by an anntena and sent to an interdigital transducer (IDT).…”