Abstract
A novel passive wireless integrated SAW-based antenna sensor for strain sensing is presented in this paper. A SAW delay line scheme is proposed for signal modulation, which could distinguish the backscattered data from environmental clutter in time domain. The theoretical relationship between the antenna resonance frequency shifts, the temperature, and the applied strain was established. A multiphysical coupled simulation process is proposed to improve the simulation accuracy. By comparing the phase shift of adjacent echoed data which is generated by SAW reflective grating, the temperature information could be extracted exactly and the effect of temperature fluctuation on the resonance frequency could be compensated. A more accurate passive (battery-free) wireless strain sensing could be provided by this proposed integrated antenna sensor than the previous proposed methods. Simulation and experimental results demonstrate the effectiveness of the sensor.
Highlights
In recent years, there has been an increasing interest in wireless sensing technologies for structural health monitoring (SHM) [1]
The temperature information is extracted from the phase variation of the adjacent reflectors of the SAW device, which could be calculated from the time domain response
Compared with previously presented antenna sensors, this proposed sensor could take the effect of temperature on the sensing result into account and a more accurate strain information could be extracted with temperature compensation for the first time
Summary
There has been an increasing interest in wireless sensing technologies for structural health monitoring (SHM) [1]. Several types of sensors have been investigated for SHM applications, including strain gauges, fiber optic sensors, and piezoelectric transducer [5, 6] These methods require lengthy cable connections and batteries for operation, which can significantly increase the total mass of the vehicle, installation time, and system cost. Frequency doubling is implemented by the Schottky diode, which might distort the backscattered signal For this reason, the strain/stress sensing accuracy of this approach is limited. The presented research realizes an integrated SAW-based patch antenna wireless passive strain sensor for use in a harsh environment. The patch antenna acts as both a usual device for receiving and radiating electromagnetic wave and a strain sensing device, and the SAW device behaves like a temperature indicator and a delay line reflector. Simulation results and experimental results show that the presented antenna sensor could compensate for the temperature change; the strain sensing accuracy could be improved
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