Wireless RF Sensor Structure for Non-Contact Vital Sign Monitoring

  • Kim, Sang-Gyu (Degree in Electrical and Electronic Engineering, Yonsei University) ;
  • Yun, Gi-Ho (School of Information and Communication Engineering, Sungkyul University) ;
  • Yook, Jong-Gwan (Degree in Electrical and Electronic Engineering, Yonsei University)
  • Received : 2011.12.21
  • Accepted : 2012.02.10
  • Published : 2012.03.31


This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.


Supported by : NIPA(National IT Industry Promotion Agency)


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