Measurements of cardiac and cardiopulmonary activities using contactless Doppler radar

Abstract

Abstract-This paper presents a wireless measurement system for cardiopulmonary activity. This system generates a continuous wave signal at 2.4 GHz toward the target and then measures the reflected signal. The target is the person's chest set at a distance of 1 m. The radar system contains a vector network analyzer, which measures the phase of S 21 . The phase variation of S 21 contains information about heart and respiration activity. Measurements are performed with two different conditions, while the person is holding respiration for 10 seconds and then breathing normally for the same duration. Filtering is used as processing technique to separate heartbeat signal from respiratory signal in the second case. The measurements were performed simultaneously with a PC-based electrocardiograph which is used as a reference to validate the information extracted from the measured signals.

Microstrip patch and Sierpinski fractal antennas: simulations and experimental characterization for vital signs detection with Doppler radar technique

“…The average peakto-peak chest displacement due to respiration is (4-12) mm, and due to the heartbeat is (0.2-0.5 mm). At rest, the respiration frequency varies in the (0.1-0.3) Hz range and the pulse in the (1-3) Hz range (16) . Considering relationship (1), phase excursion of the transmission coefficient S 21 is expected to be much higher at larger frequencies.…”

“…Vital signs, respectively respiration and heartbeat, can be quantified based on the periodic shift in the phase of the transmission coefficient S 21 when the electromagnetic wave impinges the body surface. A series of applications were developed on this basis (15)(16)(17) with the newest ones being able to quantify also the time-variability of the vital signs rhythms (18) . One of the essential components of such systems is the antenna (both the transmitting and the receiving ones).…”

Evaluation Protocol for Analogue Intelligent Medical Radars: Towards a Systematic Approach Based on Theory and a State of the Art

“…In this section, we analyse more than 50 papers on medical radar experiments in order to extract from them interesting elements about their protocols [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 ...…”

“…These walls can also be anechoic [ 39 , 45 , 66 ]. Rarely, the experiment is carried out outside with no proximate walls [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ], or surrounded by ruins [ 24 , 74 ]. Ref.…”