Systolic blood pressure estimation using wearable radar and photoplethysmogram signals

On-body Continuous Wave Radar (CWR) sensors, along with Photoplethysmogram (PPG) and Electrocardiogram (ECG) sensors, have been introduced to estimate blood pressure(BP) using time parameters as Pulse Arrival Time (PAT), Pre-ejection Period (PEP) and Pulse Transit Time (PTT) during different postures and exercises tasks. The wavelet transform is applied to the signals to remove the noise components. The on-body CWR sensor and PPG sensor are placed on the sternum and left earlobe, respectively. The time parameters of 43 healthy subjects are collected in the different sitting, standing, and supine postures, and also for 26 healthy subjects in six different exercise tasks as handgrip, light, moderate and heavy bike exercise, and two recoveries. Two different regression methods are used to estimate BP from PTT and the results are compared with the estimated BP from PAT. The best Cumulative Error Percentage (<10mmHg) is 98.2% for 38 subjects, participated in posture tasks and 88.89% for 21 subjects, participated in exercise tasks. The results show the proposed method is promising for estimating BP using PTT obtained from radar and PPG signals.