Development of chipless, wireless current sensor system based on giant magnetoimpedance magnetic sensor and surface acoustic wave transponder

Abstract

A chipless, wireless current sensor system was developed using a giant magnetoimpedance (GMI) magnetic sensor and one-port surface acoustic wave (SAW) reflective delay line for real-time power monitoring in a current-carrying conductor. The GMI sensor has a high-quality crystalline structure in each layer, which contributes to a high sensitivity and good linearity in a magnetic field of 3–16 Oe. A 400 MHz RF energy generated from the interdigital transducer (IDT)-type reflector on the one-port SAW delay line was used as an activation source for the GMI magnetic sensor. The one-port SAW delay line replaces the presently existing transceiver system, which is composed of thousands of transistors, thus enabling chipless and wireless operation. We confirmed a large variation in the amplitude of the SAW reflection peak with a change in the impedance of the GMI sensor caused by the current flow through the conductor. Good linearity and sensitivity of ~0.691 dB/A were observed for currents in the range 1–12 A. Coupling of Mode (COM) modeling and impedance matching analysis were also performed to predict the device performance in advance and these were compared with the experimental results.

Effect of IDT position parameters on SAW yarn tension sensor sensitivity

“…where k 0 is material coefficient, and it is a constant. Compare equations (1) and 3, and it is found…”

“…SAW sensors, which represent the merging of acoustic theory research, piezoelectric material achievements and electronic science and technology progress, display advantages such as high precision, simple structure, small size, easy integration, passivity, and good stability. [1][2][3][4] Because SAW sensors are particularly sensitive to the environmental changes on the substrate surface, they are widely used in the detection of physical, 5 chemical, 6 and biological 7 data. With the continuous increase in SAW sensor applications, the study of the aspects of theoretical enrichment, 8,9 working mechanism innovation, 10 simulation model improvement, 11 and working performance development 12 for SAW sensors has become a hot research topic.…”

Contactless measurement of electric current using magnetic sensors

“…The main problems with GMI are perming, if the device is not periodically demagnetized, and also temperature dependence [52]. A GMI current sensor can be coupled with an SAW transponder to form a wireless current sensor suitable for applications that do not require high accuracy [53].…”

Visual management of medical things with an advanced color-change RFID tag

“…These RFID systems are also easy to combine with various kinds of sensors. Many studies on chip and chipless RFID sensors have been carried out 19 – 25 . Chip RFID systems have been introduced to temperature 19 , vibration 20 , and moisture 21 sensors, while chipless RFID systems have been applied to pH sensing 22 .…”