Contactless and continuous blood pressure measurement according to caPTT obtained from millimeter wave radar

•A new system is first-time established to measure blood pressure contactlessly according to the central-artery pulse transit time which is acquired from the neck and chest areas simultaneously with single millimeter wave radar.•The correlation between the PTT measured by radar and contact device is verified for the first time which is up to 0.91.•Twenty-seven subjects were invited for the blood pressure estimation experiment, and the estimation error is very close to the AAMI standard.•This work provides a new method for radar-based blood pressure measurement, which is expected to promote the measurement of blood pressure in daily life. Continuous measurement of blood pressure (BP) is very important for assessing the health of the cardiovascular system. In this paper, a new system is first-time established to contactlessly and continuously measure BP according to the central-artery pulse transit time (caPTT) which is acquired from the neck and chest areas simultaneously with single millimeter wave (mmWave) radar. The two signals are separated by beam-component focusing and then BP is estimated by regression fitting. The correlation of the PTT’s variation measured by radar and contact device is verified by data from 16 subjects. The effectiveness of BP estimation is evaluated by data from 27 subjects. It is illustrated that the correlation of PTT’s variation is up to 0.91 and the errors of SBP and DBP are 5.54±7.62 mmHg and 4.68±6.15 mmHg respectively. The developed system in this work suggested that single radar has the potential to continuously measure BP in daily life.