This letter describes a compact and novel wireless vital signal 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 the body during aerobic exercise causes an input impedance variation of the radiator within the near-field range. This variation results in a corresponding change in the oscillation frequency, and this change has been utilized for detection of human vital signals. 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. Also, the autoregressive spectral estimation method is applied to achieve precise vital sign detection. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signals very accurately.
Bibliographical noteFunding Information:
Manuscript received February 19, 2012; revised March 29, 2012; accepted April 30, 2012. Date of publication May 18, 2012; date of current version May 24, 2012. This work was supported by the Ministry of Knowledge Economy (MKE ), Korea, under the Information Technology Research Center (ITRC) support program supervised by the National IT Industry Promotion Agency (NIPA) (NIPA-2012-H0301-12-1001) S.-G. Kim and J.-G. Yook are with the Department of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea (e-mail: email@example.com).
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering