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Journal of Sensors
Volume 2018, Article ID 8950807, 6 pages
Research Article

Readout Distance Enhancement of the Passive Wireless Multi-Parameter Sensing System Using a Repeater Coil

Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China

Correspondence should be addressed to Lifeng Wang; nc.ude.ues@gnefilgnaw

Received 24 October 2017; Accepted 10 January 2018; Published 12 February 2018

Academic Editor: Stephane Evoy

Copyright © 2018 Lifeng Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A repeater coil is used to extend the detection distance of a passive wireless multi-parameter sensing system. The passive wireless sensing system has the ability of simultaneously monitoring three parameters by using backscatter modulation together with channel multiplexing. Two different repeater coils are designed and fabricated for readout distance enhancement of the sensing system: one is a PCB (printed circuit board) repeater coil, and the other is a copper wire repeater coil. Under the conditions of fixed voltage and adjustable voltage, the maximum readout distance of the sensing system with and without a repeater coil is measured. Experimental results show that larger power supply voltage can help further increase the readout distance. The maximum readout distance of the sensing system with a PCB repeater coil has been extended 2.3 times, and the one with a copper wire repeater coil has been extended 3 times. Theoretical analysis and experimental results both indicate that the high Q factor repeater coil can extend the readout distance more. With the copper wire repeater coil as well as a higher power supply voltage, the passive wireless multi-parameter sensing system finally achieves a maximum readout distance of 13.5 cm.