Heart Rate Detection During Sleep Using a Flexible RF Resonator and Injection-Locked PLL Sensor

• Published in: IEEE transactions on biomedical engineering Vol. 62; no. 11; pp. 2568 - 2575
• Main Authors: Kim, Sung Woo, Choi, Soo Beom, An, Yong-Jun, Kim, Byung-Hyun, Kim, Deok Won, Yook, Jong-Gwan
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.11.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adult; Biomedical measurement; Equipment Design; Female; Heart rate; Heart Rate - physiology; Humans; Injection; Male; Monitoring; Piezoelectric transducers; Polysomnography - instrumentation; Polysomnography - methods; Radio frequencies; Radio frequency; Radio Waves; Resonant frequency; Resonators; Sensors; Signal Processing, Computer-Assisted; Sleep; Voltage-controlled oscillators; wearable sensors; Wrist; Wrist - physiology; wrist pulse; Heart rate; sleep; radio frequency; wearable sensors; wrist pulse
• ISSN: 0018-9294; 1558-2531; 1558-2531
• DOI: 10.1109/TBME.2015.2439681

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.