A Doppler Radar System for Sensing Physiological Parameters in Walking and Standing Positions

Ebrahim, Malikeh Pour; Sarvi, Majid; Yuce, Mehmet Rasit

doi:10.3390/s17030485

Cited by 20 publications

(11 citation statements)

References 18 publications

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“…In such conditions, one has to adjust for the interference because of vibration and sensor displacement. However, up-to-date monostatic Doppler radars require either on-body antenna fixation 12 or additional information about the variation of their relative position, which is several orders of magnitude greater than the amplitude of the periodic baseband signal caused by heart and breathing activity 13 . To obtain a good reflected signal (in the case of monostatic radar) the required radiation power will always be much higher than in the case of “open” operation when the locator is bistatic 17 .…”

Section: Introductionmentioning

confidence: 99%

A new radio-frequency acoustic method for remote study of liquids

Kramarenko

Savenko

2021

Sci Rep

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In the present work, a novel study method of conductive liquids has been proposed. It is based on a discovered phenomenon of radiofrequency anisotropy of electrolyte solution, which arises in response to mechanical excitation of the solution. The phenomenon was observed during the development of a radiofrequency polarimetric contactless cardiograph. The electric field vector rotates after its transition through the pericardial region due to the acceleration changes of blood. Numerous in vitro experiments with monochromatic and impulse acoustic waves always induced the polarization rotation of the RF wave passing through an electrolyte solution. The response obtained from the solutions on acoustic excitation of the Heaviside function form demonstrates the effect of a solution “memory”. The dynamics of this process resembles the spin glasses magnetization. We hypothesized that there was a magnetic moment change within the solution, and the possible reason for it is an appearance of electromagnetic impulse caused by the same acoustic excitation. In a further experiment, we really captured a suspected electrical potential. Given that, we can declare at least three new physical effects never observed before for an electrolyte solution. The study method itself may provide broad options for remote measurement of the electrolyte solution parameters.

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Section: Introductionmentioning

confidence: 99%

A new radio-frequency acoustic method for remote study of liquids

Kramarenko

Savenko

2021

Sci Rep

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“…aorta or heart. The information is derived using a mixer and a demodulator as two in-phase (I) and quadrature (Q) base-band components given by (3) and (4) 41 . The base-band signals are amplified and low pass filtered before being recorded.…”

Section: Methodsmentioning

confidence: 99%

Blood Pressure Estimation Using On-body Continuous Wave Radar and Photoplethysmogram in Various Posture and Exercise Conditions

Ebrahim

Heydari

et al. 2019

Sci Rep

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The pulse arrival time (PAT), pre-ejection period (PEP) and pulse transit time (PTT) are calculated using on-body continuous wave radar (CWR), Photoplethysmogram (PPG) and Electrocardiogram (ECG) sensors for wearable continuous systolic blood pressure (SBP) measurements. The CWR and PPG sensors are placed on the sternum and left earlobe respectively. This paper presents a signal processing method based on wavelet transform and adaptive filtering to remove noise from CWR signals. Experimental data are collected from 43 subjects in various static postures and 26 subjects doing 6 different exercise tasks. Two mathematical models are used to calculate SBPs from PTTs/PATs. For 38 subjects participating in posture tasks, the best cumulative error percentage (CEP) is 92.28% and for 21 subjects participating in exercise tasks, the best CEP is 82.61%. The results show the proposed method is promising in estimating SBP using PTT. Additionally, removing PEP from PAT leads to improving results by around 9%. The CWR sensors present a low-power, continuous and potentially wearable system with minimal body contact to monitor aortic valve mechanical activities directly. Results of this study, of wearable radar sensors, demonstrate the potential superiority of CWR-based PEP extraction for various medical monitoring applications, including BP measurement.

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“…In contrast the heart rate detection was found to be affected by the larger respiratory component. In apnea condition the heart rate was correctly detected in all 100% tests, in normal breathing condition the heart rate was correctly measured in 88% of the cases and in forced deep/fast breathing the heart rate was correctly detected in 50% of the tests indicating insufficient separation between respiratory and heart components of the measured motion Figure 17 (bottom) shows the chest displacements due to breathing measured with the radar and obtained from the phase term of (5). It is compared with the signal measured by the respiration belt transducer.…”

Section: Reflector Design and Constructionmentioning

confidence: 98%

“…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).…”

Section: System Descriptionmentioning

confidence: 99%

Collimated Beam FMCW Radar for Vital Sign Patient Monitoring

Prat

Blanch

Aguasca

et al. 2019

IEEE Trans. Antennas Propagat.

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Patient monitoring of vital signals such as breathing rhythm and heart beat rate can be done remotely by the use of a radar system. This approach is advantageous since it does not require any contact with the patient. Obviously contactless monitoring results in a more comfortable situation for the patient, and in occasions it is almost mandatory as in the case of heavy burnt or newborn patients. Moreover, additional information such movement patterns are also available. A 120 GHz FMCW radar is described with special focus on the design, construction and testing of a specific reflector antenna for the system. The system is based on a commercial radar chipset that includes its own antennas. The challenge has been to design the optimum reflector and to build it and test it in a cost effective way. The reflector has been 3D printed and a near-field testing technique has been implemented to assess its performance. The results show that the system is able to measure the vital signs at distances beyond one meter.

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A Doppler Radar System for Sensing Physiological Parameters in Walking and Standing Positions

Cited by 20 publications

References 18 publications

A new radio-frequency acoustic method for remote study of liquids

A new radio-frequency acoustic method for remote study of liquids

Blood Pressure Estimation Using On-body Continuous Wave Radar and Photoplethysmogram in Various Posture and Exercise Conditions

Collimated Beam FMCW Radar for Vital Sign Patient Monitoring

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