Sensitivity enhanced noncontact vital signal sensor using oscillation frequency deviation

Sang Gyu Kim, Gi Ho Yoon, Jong Gwan Yook

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


In this paper, a 2.4 GHz wireless vital signal sensor is proposed to detect heartbeat and respiration signals. The oscillator circuit incorporates with the planar resonator, which functions as a parallel feedback element as well as a near-field radiator. The periodic movement of a body by respiration exercise could cause the input impedance variation of the radiator within near-field range. This variation results in corresponding deviation in the oscillation frequency and it has been utilized for sensing of vital signals. In addition, a SAW filter and power detector have been used to transform the frequency variation into voltage waveform. Also, the relation of the frequency deviation of oscillator and the Q value of resonator is analyzed to increase the system sensitivity. As a result, the experimental results show that the proposed sensor placed 10 mm away from a human body can detect the vital signals very accurately.

Original languageEnglish
Title of host publicationAsia-Pacific Microwave Conference Proceedings, APMC 2011
Number of pages4
Publication statusPublished - 2011 Dec 1
EventAsia-Pacific Microwave Conference, APMC 2011 - Melbourne, VIC, Australia
Duration: 2011 Dec 52011 Dec 8

Publication series

NameAsia-Pacific Microwave Conference Proceedings, APMC


OtherAsia-Pacific Microwave Conference, APMC 2011
CityMelbourne, VIC


All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Cite this

Kim, S. G., Yoon, G. H., & Yook, J. G. (2011). Sensitivity enhanced noncontact vital signal sensor using oscillation frequency deviation. In Asia-Pacific Microwave Conference Proceedings, APMC 2011 (pp. 1586-1589). [6174069] (Asia-Pacific Microwave Conference Proceedings, APMC).