Motion Artifact-Free Magnetoplethysmogram
01 Dec 2018-
TL;DR: In this article, a noncontact magnetoplethysmogram (MPG) sensor system was devised and implemented to obtain artifact free MPG by placing a permanent magnet in proximity to a radial artery and the resulting magnetic flux detected using a flux sensor.
Abstract: A Magnetoplethysmogram (MPG) is obtained by placing a permanent magnet in proximity to a blood vessel such as radial artery and the resulting magnetic flux detected using a flux sensor. It is investigated here and shown that if either the magnet or the sensor is in contact with the skin, the resulting MPG is affected by artifacts. To eliminate such artifacts, a noncontact MPG sensor system is devised and implemented to obtain artifact free MPG. Measurements with MPG sensor in contact and without contact with the skin, obtained from 6 volunteers, establish that the MPG signals obtained using the sensor in contact with the skin is indeed affected by artifacts.
Citations
More filters
20 Jul 2020
TL;DR: An all-in-one wearable based on Giant magnetoresistance (GMR) sensor that can compute heart rate, respiration rate, blood pressure concurrently, utilizing the magneto plethysmography (MPG) signal received from the wrist.
Abstract: Wearables are quite useful in monitoring crucial parameters during patient-care in medical units and in fitness assessment. They indicate the cardiac system state of a user from the collected data and provides reliable, relevant, real-time health information about a patient. This Work describes an all-in-one wearable based on Giant magnetoresistance (GMR) sensor. The proposed device can compute heart rate (HR), respiration rate (RR), blood pressure (BP) concurrently, utilizing the magneto plethysmography (MPG) signal received from our wrist. It uses an MSP432 microcontroller and a newly developed compact 'Dual GMR- single magnet' positioning architecture.
3 citations
TL;DR: In this paper, it was shown that the maximum coupling of flux with the blood flow in radial artery occurs when the distance between the open end of the U shaped probe is 12 mm.
Abstract: Magneto plethysmo gram (MPG), like the Photo plethysmo gram (PPG) is a signal that carries information on blood volume flow and is obtained noninvasively. Unlike PPG, MPG is obtained from a peripheral artery, such as radial, carotid or brachial. The magnetic flux required for obtaining an MPG is generated by a permanent magnet placed on the wrist surface such that the generated flux couples with the blood flow in the artery. In this work it is shown that maximum coupling of flux with the blood flow in radial artery occurs when the distance between the open end of the U shaped probe is 12 mm. In order to attain this result, first the probe is simulated using the finite element method. The distance between the pole faces is varied in steps of 1 mm. Simulation results clearly indicate that the optimal distance is 12mm. Next experiments were conducted with prototype probes of varying distances between the pole faces on 20 volunteers of different age and gender. The experimental results validate the result obtained by the simulation study.
2 citations
Cites background from "Motion Artifact-Free Magnetoplethys..."
...Unlike PPG, MPG sensors are placed near an artery such as radial, carotid, or brachial [28]–[30]....
[...]
TL;DR: Results from the clinical validation establish the practicability of the proffered magnetoplethysmogram system and the basic principle of modulated magnetic signature of blood (MMSB), is validated with clinical trial.
Abstract: A novel magnetoplethysmogram (MPG) system is designed and developed for the real time, noninvasive monitoring of hemoglobin concentration in arterial blood. The basic principle of modulated magnetic signature of blood (MMSB), is validated with clinical trial. The MPG probe consists of a permanent magnet and a Giant Magneto Resistance (GMR) sensor. A strap and stand design enable reliable capture of continuous cycles of MPG with relative ease. Clinical validation with data from 64 patients carried out at the institute hospital of IIT Madras, using the proposed system gave a worst-case error of 6.5% in the measurement of hemoglobin concentration in arterial blood. Linear regression analysis using least square method, exhibited a standard deviation of 0.64 g/dL. Results from the clinical validation establish the practicability of the proffered MPG system.
2 citations
References
More filters
TL;DR: A novel method of computation of SpO2 that does not require the use of a calibration curve is presented, based on a model for the attenuation of light through skin, tissue, bone, and blood, that becomes free of not only patient but sensor-dependent parameters as well.
Abstract: In present-day pulse oximeters, oxygen saturation in arterial blood (SpO2) is computed by utilizing an empirical relationship extracted from a calibration curve. The calibration curve is obtained by curve-fitting data acquired from volunteers. A novel method of computation of SpO2 that does not require the use of a calibration curve is presented in this paper. Based on a model for the attenuation of light through skin, tissue, bone, and blood, suitable processing steps are identified so that the analytical expression derived for the estimation of SpO2 becomes free of not only patient but sensor-dependent parameters as well. The experimental results presented in this paper establish the efficacy of the proposed method.
80 citations
TL;DR: Variations were more common at the radial side of the arch and on left hands, and the radial artery was significantly larger than the ulnar artery but the ulna artery to be smaller than the superficial branch of the radial arteries.
Abstract: Although anatomical variations in the arterial pattern of the hand have been the subject of many studies, information on the diameter of the superficial palmar arch contributing vessels and its branches are rarely found in the literature. The objective of the current study was to evaluate these arterial variations, with special attention to the diameter of the superficial palmar arch contributing vessels and its major branches. Forty-six hands from male embalmed human cadavers were evaluated, 21 right hands and 25 left hands. Complete arches were present in 43% on the right and in 52% on the left. Arches were completed by the median artery in two cases. Variations were more common at the radial side of the arch and on left hands. Comparison of vessel diameters revealed the radial artery to be significantly larger than the ulnar artery but the ulnar artery to be larger than the superficial branch of the radial artery. The diameters of the common digital arteries were not different with regard to complete or incomplete arches, or with regard to the presence of the median artery.
78 citations
"Motion Artifact-Free Magnetoplethys..." refers background in this paper
...1 mm [14], the peak value of the AC part is estimated using (10)....
[...]
TL;DR: The purpose of this study was to assess the accuracy of Doppler-based measurement of instantaneous aortic blood flow and waveform morphology throughout ventricular ejection when compared with an established invasive method.
Abstract: Assessment of the pulsatile mechanical behavior of the coupled left ventricle and the peripheral arterial circulation requires accurate estimation of instantaneous aortic flow. Before the availability of Doppler technologies, this could only be achieved by invasive techniques. The purpose of this study was to assess the accuracy of Doppler-based measurement of instantaneous aortic blood flow and waveform morphology throughout ventricular ejection when compared with an established invasive method. Accordingly, data from electromagnetic flow and continuous-wave aortic Doppler recordings were simultaneously acquired and compared in five monkeys over a wide range of flows generated by intravenous infusions of the beta-adrenoceptor agonist dobutamine and the alpha-receptor agonist methoxamine. Instantaneous aortic pressure was measured using a high-fidelity micromanometer-tipped catheter placed in the ascending aorta. Excellent correlations were noted for stroke volume, cardiac output, left ventricular ejection time, maximal flow velocity, and maximal rate of change of flow velocity (dQ/dtmax). When compared with electromagnetic flows, continuous-wave aortic Doppler had significantly lower times to maximal flow velocity and dQ/dtmax. Frequency domain analysis indicated that both the magnitude and phase were within +/- 6% up to the third harmonic. Instantaneous comparison disclosed that during early systole (up to 10% of ejection) Doppler was higher than electromagnetic flow rate by 11 +/- 19% (p less than 0.05). At 20-30% of systolic ejection, electromagnetic flow rates were slightly higher than Doppler (5 +/- 4% at 20% of ejection, p less than 0.001 and 2 +/- 3% at 30% of ejection, p less than 0.05). From 40% of ejection to the end of systole, flow rates using both techniques were virtually identical.(ABSTRACT TRUNCATED AT 250 WORDS)
40 citations
"Motion Artifact-Free Magnetoplethys..." refers methods in this paper
...MPG has also been applied for the determination of: cardiac volume changes [7], aortic flow [8], blood velocity [9] and concentration of haemoglobin in arterial blood [10]....
[...]
TL;DR: The ventricular ejection of blood was clearly exhibited in signals measured above the heart and related to the blood flow in the aortic arch and in the abdominal aorta, respectively tively.
Abstract: Magnetic susceptibility plethysmography (MSPG) is a non-invasive technique for detecting changes in the total cardiac volume. The MSPG signal is observed with a sensitive magnetometer when an external magnetic field is applied to the thorax. The signal is due to the differences in magnetic susceptibilities of intracardiac blood, heart muscle, and surrounding tissues. In this work the spatial distribution of the MSPG signal across the chest of normal subjects is presented. The ventricular ejection of blood was clearly exhibited in signals measured above the heart. Relatively large MSPG signals were also observed on the upper and lower thorax during the ventricular ejection, related to the blood flow in the aortic arch and in the abdominal aorta, respectively tively. The temporal behavior of the MSPG is compared with the results obtained from existing clinical methods. The origin of the MSPG signal is analyzed theoretically. When a fixed cardiac magnetic dipole model was used, overall change in cardiac volume as a function of time could be evaluated with reasonable accuracy when the proximity effect of the torso was taken into account.
23 citations
"Motion Artifact-Free Magnetoplethys..." refers methods in this paper
...MPG has also been applied for the determination of: cardiac volume changes [7], aortic flow [8], blood velocity [9] and concentration of haemoglobin in arterial blood [10]....
[...]
TL;DR: In order to detect blood volume changes, the new magnetic plethysmographic sensor using time-varying magnetic fields was proposed, and thereby, measuring the change of impedance of exciting coil, which inductively coupled with exciting coil.
Abstract: In order to detect blood volume changes, we proposed the new magnetic plethysmographic sensor using time-varying magnetic fields, and thereby, measuring the change of impedance of exciting coil. The change of coil impedance was proportional to the change of blood volume passing through a volume-of-interests, which inductively coupled with exciting coil. In order to verify the feasibility of the proposed method, photo-plethysmographic and magneto-plethysmographic (MPG) signals were recorded from the index and middle finger of the left hand simultaneously. Comparison of the proposed sensor signals with ultrasound Doppler blood flow velocity recordings shows the excellent correlation (r = 0.9355, p <; 0.01) and the RR intervals derived from electrocardiograph and MPG signals showed a very high degree of correlation (r = 0.9823, p <; 0.01).
23 citations
"Motion Artifact-Free Magnetoplethys..." refers methods in this paper
...MPG has also been applied for the determination of: cardiac volume changes [7], aortic flow [8], blood velocity [9] and concentration of haemoglobin in arterial blood [10]....
[...]