In this paper, a compact vital signal sensing method using oscillation frequency deviation at 2.4-GHz industrial-scientific-medical band is proposed to detect vital signals, such as heartbeat and respiration signal. The oscillation circuit of the proposed vital sensor system has been realized by a planar resonator, which functions as a positive feedback element, as well as a near-field radiator to sense vital signals, simultaneously. The periodic movement of a body by respiration exercise causes the impedance variation of the radiator within the near-field range. The impedance variation results in a corresponding change in the oscillation frequency, and this variation has been utilized for sensing of the vital signals. In addition, a surface acoustic wave filter and power detector have been used to increase the sensitivity of the system and to transform the frequency variation to voltage waveform. The experimental results show that the proposed vital sensor placed 20 mm from the body can detect the heartbeat waveform very accurately.
|Number of pages||8|
|Journal||IEEE Transactions on Microwave Theory and Techniques|
|Publication status||Published - 2012 Feb|
Bibliographical noteFunding Information:
Manuscript received July 03, 2011; revised October 11, 2011; accepted October 21, 2011. Date of publication December 09, 2011; date of current version February 03, 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-2010-(C1090-1011-0006)].
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Electrical and Electronic Engineering