Mitigation of Body Movement Interference in Near-Field Coherent Sensing for Heart Rate Monitoring

Xiaonan Hui1, Edwin Kan

  • 1Cornell University

Details

13:15 - 13:30 | Wed 7 Mar | Antilles CD | WeBT1.4

Session: BSN Session # 6 – Cardiovascular Monitoring using BSN

Abstract

Users of wearable devices often hope to collect continuous personal vital signs such as heart rates, blood pressures, respiration rates and breath efforts with comfort and free movement. Current approaches are however hindered by their accuracy, comfort, convenience, power consumptions and sensing capabilities. The requirement of direct skin contacts in electrocardiogram (ECG) and acoustic methods limits their sensation of comfort, wearing convenience, body motion and hence long-term use. Photo-plethysmography (PPG) in wrist watches and finger clamps do not require immediate skin touch but its signal can be severely degraded by relative movement. In this paper, we introduce a new method modulating the external and internal motion of the wearer body directly onto multiplexed radio frequency (RF) signals by near-field coherent sensing (NCS). To minimize the deployment and maintenance cost of NCS vital-sign monitoring, passive (battery-free) RF identification (RFID) tags can be integrated into garments at the chest and wrist areas as laundry-ready wearable devices. NCS utilizes both amplitude and phase of the RF signals to sense and isolate the vital signs, which significantly increases the signal quality in comparison to methods based solely on signal strength. The high frequency components of the NCS signal is employed to mitigate the body movement interference to obtain more accurate heart rates.