Heart rate detection during sleep using a flexible RF resonator and injection-locked PLL sensor

Sung Woo Kim, Soo Beom Choi, Yong Jun An, Byung Hyun Kim, Deok Won Kim, Jong Gwan Yook

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Novel nonintrusive technologies for wrist pulse detection have been developed and proposed as systems for sleep monitoring using three types of radio frequency (RF) sensors. The three types of RF sensors for heart rate measurement on wrist are a flexible RF single resonator, array resonators, and an injection-locked PLL resonator sensor. To verify the performance of the new RF systems, we compared heart rates between presleep time and postsleep onset time. Heart rates of ten subjects were measured using the RF systems during sleep. All three RF devices detected heart rates at 0.2 to 1 mm distance from the skin of the wrist over clothes made of cotton fabric. The wrist pulse signals of a flexible RF single resonator were consistent with the signals obtained by a portable piezoelectric transducer as a reference. Then, we confirmed that the heart rate after sleep onset time significantly decreased compared to before sleep. In conclusion, the RF system can be utilized as a noncontact nonintrusive method for measuring heart rates during sleep.

Original languageEnglish
Article number7118670
Pages (from-to)2568-2575
Number of pages8
JournalIEEE Transactions on Biomedical Engineering
Issue number11
Publication statusPublished - 2015 Nov 1

Bibliographical note

Publisher Copyright:
© 1964-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Biomedical Engineering


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