Evaluation of a Doppler radar sensor system for vital signs detection and activity monitoring in a radio-frequency shielded room

Abstract

a b s t r a c tThis study presents an evaluation of an advanced Doppler radar-based method for detection of vital signs, presence, and activity of a human subject in a test room with radar-signal reflecting aluminum-coated surfaces. Ten test subjects lay in four positions, and they sat in two locations in the room, both breathing normally and holding their breath. The mean ratios of the pulse rates determined from the radar signal and electrocardiography and respiration reference signals were 110% (respiration) and 99% (heartbeat), and the mean occupied and empty room radar signal variance ratios were 608 (breathing) and 20 (breath-hold). In a one-subject activity monitoring test, walking, standing and lying activities could be well separated from the radar signal. The results are promising and the proposed system seems to have potential to be used in position-independent health and activity monitoring of, for example, elderly people in care homes or intoxicated people in police custody.

Collimated Beam FMCW Radar for Vital Sign Patient Monitoring

“…2, in a FMCW radar the detected signal is the result of the beating between the transmitted and received signal. Its time variation can be expressed as: ( 5 ) From (5) the detected signal corresponding to a target at a distance R will have a frequency shown in (6), corresponding to the first term of (5), and a linear phase term shown in (7), corresponding to the second term in (5).…”

“…Early proposals of remote monitoring systems based in radar measurements of thorax movements can be found in [2] and [3]. More recently Doppler measurements to monitor vital signs with continuous wave (CW) radars have been presented at frequencies of 4, 16 and 34 GHz [4][5] [6]. In this work, we propose a real-time, contactless and non-obstructive system for heartbeat and breathing rate monitoring operating in the ISM band of 120 GHz.…”

MEMS-Based Sensor for Simultaneous Measurement of Pulse Wave and Respiration Rate

“…However, because the PPG response could be altered by several factors, such as ambient light, muscle movement, and skin dilation [19], this method is not suitable for use during motion of the body, including physical exercise. Another approach involves the use of radar to detect the deformation of the chest due to both heartbeat and respiration [20,21]. However, this method is also not suitable for measurement during outdoor activities because it requires the measurements to be performed in a designated space with radar equipment.…”

Feasibility of Remote Vital Signs Sensing with a mm-Wave CW Reflectometer

“…Many studies have been published in the field of RF-based VS monitoring including different radar setups and operation at various frequency bands. In [1] a continuous wave (CW) radar operating at 34 GHz was proposed for HR and BR measurement for persons lying, sitting and walking at distances up to 2 m. In [2] a CW radar at 94 GHz is proposed for HR and BR monitoring at distances up to 9 m. [3] and [4] propose an ultra-wideband (UWB) impulse radar at 1.4-4.5 GHz and a frequency modulated continuous wave (FMCW) radar at 60 GHz respectively for the monitoring of both BR and HR. Finally an FMCW radar is proposed in [5] at 5.8 GHz where only BR is considered.…”