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Search Results (651)

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Keywords = heart rate sensor

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14 pages, 5896 KiB  
Article
Validity and Reliability of Wearable Sensors for Continuous Postoperative Vital Signs Monitoring in Patients Recovering from Trauma Surgery
by Rianne van Melzen, Marjolein E. Haveman, Richte C. L. Schuurmann, Kai van Amsterdam, Mostafa El Moumni, Monique Tabak, Michel M. R. F. Struys and Jean-Paul P. M. de Vries
Sensors 2024, 24(19), 6379; https://doi.org/10.3390/s24196379 - 1 Oct 2024
Abstract
(1) Background: Wearable sensors support healthcare professionals in clinical decision-making by measuring vital parameters such as heart rate (HR), respiration rate (RR), and blood oxygenation saturation (SpO2). This study assessed the validity and reliability of two types of wearable sensors, [...] Read more.
(1) Background: Wearable sensors support healthcare professionals in clinical decision-making by measuring vital parameters such as heart rate (HR), respiration rate (RR), and blood oxygenation saturation (SpO2). This study assessed the validity and reliability of two types of wearable sensors, based on electrocardiogram or photoplethysmography, compared with continuous monitoring of patients recovering from trauma surgery at the postanesthesia care unit. (2) Methods: In a prospective observational study, HR, RR, SpO2, and temperature of patients were simultaneously recorded with the VitalPatch and Radius PPG and compared with reference monitoring. Outcome measures were formulated as correlation coefficient for validity and mean difference with 95% limits of agreement for reliability for four random data pairs and 30-min pairs per vital sign per patient. (3) Results: Included were 60 patients. Correlation coefficients for VitalPatch were 0.57 to 0.85 for HR and 0.08 to 0.16 for RR, and for Radius PPG, correlation coefficients were 0.60 to 0.83 for HR, 0.20 to 0.12 for RR, and 0.57 to 0.61 for SpO2. Both sensors presented mean differences within the cutoff values of acceptable difference. (4) Conclusions: Moderate to strong correlations for HR and SpO2 were demonstrated. Although mean differences were within acceptable cutoff values for all vital signs, only limits of agreement for HR measured by electrocardiography were considered clinically acceptable. Full article
(This article belongs to the Special Issue Advanced Wearable Sensors for Medical Applications)
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<p>Placement of the wearable sensors on the participant’s body: (1) VitalPatch for HR and RR based on ECG and temperature; (2) Masimo Radius T for temperature; and (3) Masimo Radius PPG measuring HR (pulse rate), RR and Sp<span class="html-small-caps">O</span><sub>2</sub> based on PPG.</p>
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<p>Bland–Altman plots for the Radius PPG vs. reference (upper row) and VitalPatch vs. reference (lower row) for the 4 randomly selected data pairs per patient for each vital sign: heart rate (HR) in beats/min (bpm); respiration rate (RR) in breaths/min (brpm); and blood oxygen saturation (Sp<span class="html-small-caps">O</span><sub>2</sub>) in percentage (%). The x-axis represents the mean, and the y-axis represents the difference (Δ) between both measurement pairs. The dotted lines represent the mean difference and 95% limits of agreement for repeated measurements. The heat map represents the number of pairs in the specific bin.</p>
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<p>Bland–Altman plots for the Radius PPG vs. reference (upper row) and VitalPatch vs. reference (lower row) for the 30-min median value pairs per patient for each vital sign: heart rate (HR) in beats/min (bpm), respiration rate (RR) in breaths/min (brpm), and blood oxygen saturation (Sp<span class="html-small-caps">O</span><sub>2</sub>) in percentage (%). The x-axis represents the mean, and the y-axis represents the difference (Δ) between both measurement pairs. The dotted lines represent the mean difference and 95% limits of agreement for repeated measurements. The heat map represents the number of pairs in the specific bin.</p>
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<p>Scatterplot for the validity analysis of the Radius PPG compared with the reference monitor for heart rate (HR) measured in beats per minute (bpm). The green cluster demonstrates data from a patient in whom an unknown rhythm was detected by the reference monitor. The x-axis presents HR measured with the reference monitor at the postanesthesia care unit (PACU), and the y-axis represents HR measured by Radius PPG in bpm. The dots represent the data from each patient by a specific color. The lines represent the correlation coefficient per patient.</p>
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<p>Heart rate (HR) in beats per min (bpm) of a patient demonstrating the comparison of Radius PPG HR (red) and HR measured by the photoplethysmography (Pleth) monitor at the postanesthesia care unit (PACU; yellow) versus HR measured based on electrocardiogram (ECG) by VitalPatch (dark blue) and ECG reference monitor at the PACU (light blue). The y-axis represents HR in bpm, and the x-axis represents time in hours.</p>
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12 pages, 545 KiB  
Review
Wearable Sensors for Healthcare of Industrial Workers: A Scoping Review
by Juhyun Moon and Byeong-Kwon Ju
Electronics 2024, 13(19), 3849; https://doi.org/10.3390/electronics13193849 - 28 Sep 2024
Viewed by 499
Abstract
Background and Objectives: This scoping review evaluates the use of wearable sensor technologies for workplace safety and health monitoring in industrial settings. The aim is to synthesize evidence on the impact of these sensors and their application in high-risk environments. Materials and Methods: [...] Read more.
Background and Objectives: This scoping review evaluates the use of wearable sensor technologies for workplace safety and health monitoring in industrial settings. The aim is to synthesize evidence on the impact of these sensors and their application in high-risk environments. Materials and Methods: Following the PRISMA guidelines, a systematic search across four international electronic databases yielded 59 studies, of which 17 were included in the final review. The selection criteria involved studies that specifically utilized wearable sensors to monitor various health and environmental parameters relevant to industrial workers. Results: The analysis categorizes wearable technologies into five distinct groups based on their function: gas monitoring technologies, heart rate and physiological data collection, fatigue and activity monitoring, comprehensive environmental and physiological monitoring, and advanced sensing and data collection systems. These devices demonstrated substantial benefits in terms of early detection of health risks and enhancement of safety protocols. Conclusions: The review concludes that wearable sensor technologies significantly contribute to workplace safety by providing real-time, data-driven insights into environmental hazards and workers’ physiological status, thus supporting proactive health management practices in industrial settings. Further research is recommended to address the challenges of data privacy, sensor reliability, and cost-effective integration to maximize their potential in occupational health safety. Full article
(This article belongs to the Section Bioelectronics)
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<p>Scoping review flow diagram.</p>
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10 pages, 1334 KiB  
Article
Validation of a Textile-Based Wearable Measuring Electrocardiogram and Breathing Frequency for Sleep Apnea Monitoring
by Florent Baty, Dragan Cvetkovic, Maximilian Boesch, Frederik Bauer, Neusa R. Adão Martins, René M. Rossi, Otto D. Schoch, Simon Annaheim and Martin H. Brutsche
Sensors 2024, 24(19), 6229; https://doi.org/10.3390/s24196229 - 26 Sep 2024
Viewed by 301
Abstract
Sleep apnea (SA) is a prevalent disorder characterized by recurrent events of nocturnal apnea. Polysomnography (PSG) represents the gold standard for SA diagnosis. This laboratory-based procedure is complex and costly, and less cumbersome wearable devices have been proposed for SA detection and monitoring. [...] Read more.
Sleep apnea (SA) is a prevalent disorder characterized by recurrent events of nocturnal apnea. Polysomnography (PSG) represents the gold standard for SA diagnosis. This laboratory-based procedure is complex and costly, and less cumbersome wearable devices have been proposed for SA detection and monitoring. A novel textile multi-sensor monitoring belt recording electrocardiogram (ECG) and breathing frequency (BF) measured by thorax excursion was developed and tested in a sleep laboratory for validation purposes. The aim of the current study was to evaluate the diagnostic performance of ECG-derived heart rate variability and BF-derived breathing rate variability and their combination for the detection of sleep apnea in a population of patients with a suspicion of SA. Fifty-one patients with a suspicion of SA were recruited in the sleep laboratory of the Cantonal Hospital St. Gallen. Patients were equipped with the monitoring belt and underwent a single overnight laboratory-based PSG. In addition, some patients further tested the monitoring belt at home. The ECG and BF signals from the belt were compared to PSG signals using the Bland-Altman methodology. Heart rate and breathing rate variability analyses were performed. Features derived from these analyses were used to build a support vector machine (SVM) classifier for the prediction of SA severity. Model performance was assessed using receiver operating characteristics (ROC) curves. Patients included 35 males and 16 females with a median age of 49 years (range: 21 to 65) and a median apnea-hypopnea index (AHI) of 33 (IQR: 16 to 58). Belt-derived data provided ECG and BF signals with a low bias and in good agreement with PSG-derived signals. The combined ECG and BF signals improved the classification accuracy for SA (area under the ROC curve: 0.98; sensitivity and specificity greater than 90%) compared to single parameter classification based on either ECG or BF alone. This novel wearable device combining ECG and BF provided accurate signals in good agreement with the gold standard PSG. Due to its unobtrusive nature, it is potentially interesting for multi-night assessments and home-based patient follow-up. Full article
(This article belongs to the Special Issue Sensors for Breathing Monitoring)
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<p>Textile multi-sensor belt for continuous monitoring of cardiac and breathing parameters. The left panel displays the belt mounted on the thorax. The right panel displays the skin-facing site of the multi-sensor belt with embroidered electrodes (1) and pressure-sensitive optical fibers (2).</p>
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<p>Patient workflow and numbers of eligible data for sub-analyses.</p>
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<p>Whole-night ECG signal quality of the monitoring belt. Two illustrative patients are presented, including a good quality data set (<b>left panel</b>) and a poor quality data set (<b>right panel</b>). A locally-weighted polynomial regression smoother was applied and is represented by a red line. The whole-night statistics measured by the whole-night averaged Pearson’s correlation coefficient (<math display="inline"><semantics> <mover accent="true"> <mi>r</mi> <mo>¯</mo> </mover> </semantics></math>) and associated standard deviation are provided at the bottom left corner of both panels.</p>
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<p>Bland-Altman agreement analyses comparing whole-night mean instantaneous heart rates (HR, <b>left panel</b>) and mean instantaneous breathing rates (BR, <b>right panel</b>) measured by the belt and PSG. The mean difference (bias) and 95% limits of agreement are represented by dashed lines. The 95% confidence intervals of the mean difference are represented by dotted lines.</p>
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<p>ROC curves of the prediction accuracy of apnea severity from the monitoring belt (<b>left panel</b>) and the PSG (<b>right panel</b>). The area under the curves (AUC) obtained from ECG (blue circles), BF (red circles), and the combined ECG + BF (purple circles) are provided together with the 95% confidence intervals. Smoothing ROC curves are represented by dashed lines.</p>
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16 pages, 13292 KiB  
Article
Inferring ECG Waveforms from PPG Signals with a Modified U-Net Neural Network
by Rafael Albuquerque Pinto, Hygo Sousa De Oliveira, Eduardo Souto, Rafael Giusti and Rodrigo Veras
Sensors 2024, 24(18), 6046; https://doi.org/10.3390/s24186046 - 19 Sep 2024
Viewed by 735
Abstract
There are two widely used methods to measure the cardiac cycle and obtain heart rate measurements: the electrocardiogram (ECG) and the photoplethysmogram (PPG). The sensors used in these methods have gained great popularity in wearable devices, which have extended cardiac monitoring beyond the [...] Read more.
There are two widely used methods to measure the cardiac cycle and obtain heart rate measurements: the electrocardiogram (ECG) and the photoplethysmogram (PPG). The sensors used in these methods have gained great popularity in wearable devices, which have extended cardiac monitoring beyond the hospital environment. However, the continuous monitoring of ECG signals via mobile devices is challenging, as it requires users to keep their fingers pressed on the device during data collection, making it unfeasible in the long term. On the other hand, the PPG does not contain this limitation. However, the medical knowledge to diagnose these anomalies from this sign is limited by the need for familiarity, since the ECG is studied and used in the literature as the gold standard. To minimize this problem, this work proposes a method, PPG2ECG, that uses the correlation between the domains of PPG and ECG signals to infer from the PPG signal the waveform of the ECG signal. PPG2ECG consists of mapping between domains by applying a set of convolution filters, learning to transform a PPG input signal into an ECG output signal using a U-net inception neural network architecture. We assessed our proposed method using two evaluation strategies based on personalized and generalized models and achieved mean error values of 0.015 and 0.026, respectively. Our method overcomes the limitations of previous approaches by providing an accurate and feasible method for continuous monitoring of ECG signals through PPG signals. The short distances between the infer-red ECG and the original ECG demonstrate the feasibility and potential of our method to assist in the early identification of heart diseases. Full article
(This article belongs to the Special Issue Advanced Sensor Technologies for Biomedical-Information Processing)
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<p>Overview of the PPG2ECG method generation process.</p>
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<p>(<b>a</b>) Representation of the data after segmentation. (<b>b</b>) Graphical representation of the segmented PPG and ECG signals in overlapping windows.</p>
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<p>UNet Inception architecture used to generate an ECG signal.</p>
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<p>Comparison between the original ECG and the reconstructed ECG signals using the PPG2ECG method with the generalized model. (<b>a</b>) Original ECG and ECG reconstructed using the PPG2ECG method with the generalized model, and (<b>b</b>) PPG signal was used to reconstruct the waveform of the ECG signal.</p>
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<p>(<b>a</b>) Original ECG and ECGreconstructed using the PPG2ECG method with the personalized model, and (<b>b</b>) PPG signal was used to reconstruct the waveform of the ECG signal.</p>
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<p>Visual comparison of the ECG reconstruction for a random user using the following methods: (<b>a</b>) CardioGAN; (<b>b</b>) Attention-based Transformers; and (<b>c</b>) Proposed PPG2ECG.</p>
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11 pages, 1060 KiB  
Article
Limitations in Maximum Intensity Front Crawl in Swimmers with Down Syndrome
by Giampiero Merati, Damiano Formenti, Claudio Gandola, Paolo Castiglioni, Linda Casalini, Athos Trecroci, Luca Cavaggioni, Pietro Luigi Invernizzi, Umberto Menichino and Raffaele Scurati
Appl. Sci. 2024, 14(18), 8387; https://doi.org/10.3390/app14188387 - 18 Sep 2024
Viewed by 631
Abstract
Individuals with Down Syndrome exhibit deficits in muscle strength and cardiovascular adaptation, which limit athletic performance. We compared a maximum-intensity 50 m front crawl test between competitive male swimmers with Down Syndrome (SDS; n = 11; 26.5 ± 5.6 years; m ± SD) [...] Read more.
Individuals with Down Syndrome exhibit deficits in muscle strength and cardiovascular adaptation, which limit athletic performance. We compared a maximum-intensity 50 m front crawl test between competitive male swimmers with Down Syndrome (SDS; n = 11; 26.5 ± 5.6 years; m ± SD) and a control group of swimmers (CNT; n = 11; 27.1 ± 4.0 years) with similar training routines (about 5 h/week). Wearable sternal sensors measured their heart rate and 3D accelerometry. The regularity index Sample Entropy (SampEn) was calculated using the X component of acceleration. The total times (SDS: 58.91 ± 13.68 s; CNT: 32.55 ± 3.70 s) and stroke counts (SDS: 66.1 ± 9.6; CNT: 51.4 ± 7.4) were significantly higher in the SDS group (p < 0.01). The heart rate was lower in the SDS group during immediate (SDS: 129 ± 15 bpm; CNT: 172 ± 11 bpm) and delayed recovery (30 s, SDS: 104 ± 23 bpm; CNT: 145 ± 21 bpm; 60 s, SDS: 79 ± 27 bpm; CNT: 114 ± 27 bpm) (p < 0.01 for all the comparisons). The SampEn of sternal acceleration showed no differences between the groups and between 0–25 m and 25–50 m. Body pitch correlated strongly with performance in the SDSs (R2 = 0.632, p < 0.01), but during the first 25 m only. The high-intensity front crawl performances differed between the SDS and CNT athletes in terms of time, biomechanics, and training adaptation, suggesting the need for tailored training to improve swimming efficiency in SDSs. Full article
(This article belongs to the Special Issue Advances in Assessment of Physical Performance)
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<p>Recording of the triaxial accelerometry (Faros 180<sup>®</sup>; sampling frequency: 100 Hz, values expressed in mg: 1 mg = 9.80665 × 10<sup>−3</sup> m/s<sup>2</sup>) from a representative subject. The accelerometer was placed on the swimmer’s sternum, with the reference orientation of the 3 axes indicated in the upper right corner of the figure. From these traces, length times and stroke counts were obtained; the SampEn regularity index was evaluated on the acceleration of the longitudinal axis of motion (X component).</p>
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<p>HR values at rest (REST), immediately after the 50 m front crawl test (50 m END), and after 30 (30 s REC) and 60 s (60 s REC) of post-test recovery. Data are presented as the mean ± SD. Black squares and continuous line: CNT group; White circles and dashed line: SDS group. The * indicates differences between the SDS vs. CNT groups significant at <span class="html-italic">p</span> &lt; 0.001 in the post-hoc analysis of two-way ANOVA.</p>
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<p>Relationships, estimated through simple linear regression analysis, between the angle of inclination relative to the plane (body pitch) of the water and the lap time, separately for the first (0–25 m, panel (<b>a</b>)) and second length (25–50 m, panel (<b>b</b>)) of the 50 m swimming test. Black squares: CNT group; white circles: SDS group.</p>
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17 pages, 652 KiB  
Article
Sensor-Based Real-Time Monitoring Approach for Multi-Participant Workout Intensity Management
by José Saias and Jorge Bravo
Electronics 2024, 13(18), 3687; https://doi.org/10.3390/electronics13183687 - 17 Sep 2024
Viewed by 393
Abstract
One of the significant advantages of technological evolution is the greater ease of collecting and analyzing data. Miniaturization, wireless communication protocols and IoT allow the use of sensors to collect data, with all the potential to support decision making in real time. In [...] Read more.
One of the significant advantages of technological evolution is the greater ease of collecting and analyzing data. Miniaturization, wireless communication protocols and IoT allow the use of sensors to collect data, with all the potential to support decision making in real time. In this paper, we describe the design and implementation of a digital solution to guide the intensity of training or physical activity, based on heart rate wearable sensors applied to participants in group sessions. Our system, featuring a unified engine that simplifies sensor management and minimizes user disruption, has been proven effective for real-time monitoring. It includes custom alerts during variable-intensity workouts, and ensures data preservation for subsequent analysis by physiologists or clinicians. This solution has been used in sessions of up to six participants and sensors up to 12 m away from the gateway device. We describe some challenges and constraints we face in collecting data from multiple and possibly different sensors simultaneously via Bluetooth Low Energy, and the approaches we follow to overcome them. We conduct an in-depth questionnaire to identify potential obstacles and drivers for system acceptance. We also discuss some possibilities for extension and improvement of our system. Full article
(This article belongs to the Section Computer Science & Engineering)
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<p>Home view for coordinators: history of sessions held and participant records lists.</p>
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<p>Visual data representations: two participant HR zones. In (<b>a</b>), there is little alignment with the training goal, whereas in (<b>b</b>) the participant stayed predominantly within the target zone.</p>
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<p>Session setup: sequence of steps to assign a sensor to a participant. (<b>a</b>) Listing two active sensors not yet assigned. (<b>b</b>) Pairing a sensor with a participant (named Joaquim) and his lower and upper HR limits. (<b>c</b>) Confirmation grid with the already activated sensor/participant pairs.</p>
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<p>Session monitoring dashboard with two participants.</p>
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<p>Variable intensity mode: effort zone control widget.</p>
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<p>Monitoring panel in variable intensity mode: zone indicator and color codes. (<b>a</b>) Zone indicator below the training objective. (<b>b</b>) Participant zone indicator complies with the intended effort level. (<b>c</b>) The HR zone value is very high considering the session objective.</p>
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<p>Session summary: time, duration, participants, sensors, and indicators.</p>
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<p>Monitoring system architecture: modules and interconnections between them.</p>
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17 pages, 1647 KiB  
Article
Advanced Necklace for Real-Time PPG Monitoring in Drivers
by Anna Lo Grasso, Pamela Zontone, Roberto Rinaldo and Antonio Affanni
Sensors 2024, 24(18), 5908; https://doi.org/10.3390/s24185908 - 12 Sep 2024
Viewed by 336
Abstract
Monitoring heart rate (HR) through photoplethysmography (PPG) signals is a challenging task due to the complexities involved, even during routine daily activities. These signals can indeed be heavily contaminated by significant motion artifacts resulting from the subjects’ movements, which can lead to inaccurate [...] Read more.
Monitoring heart rate (HR) through photoplethysmography (PPG) signals is a challenging task due to the complexities involved, even during routine daily activities. These signals can indeed be heavily contaminated by significant motion artifacts resulting from the subjects’ movements, which can lead to inaccurate heart rate estimations. In this paper, our objective is to present an innovative necklace sensor that employs low-computational-cost algorithms for heart rate estimation in individuals performing non-abrupt movements, specifically drivers. Our solution facilitates the acquisition of signals with limited motion artifacts and provides acceptable heart rate estimations at a low computational cost. More specifically, we propose a wearable sensor necklace for assessing a driver’s well-being by providing information about the driver’s physiological condition and potential stress indicators through HR data. This innovative necklace enables real-time HR monitoring within a sleek and ergonomic design, facilitating seamless and continuous data gathering while driving. Prioritizing user comfort, the necklace’s design ensures ease of wear, allowing for extended use without disrupting driving activities. The collected physiological data can be transmitted wirelessly to a mobile application for instant analysis and visualization. To evaluate the sensor’s performance, two algorithms for estimating the HR from PPG signals are implemented in a microcontroller: a modified version of the mountaineer’s algorithm and a sliding discrete Fourier transform. The goal of these algorithms is to detect meaningful peaks corresponding to each heartbeat by using signal processing techniques to remove noise and motion artifacts. The developed design is validated through experiments conducted in a simulated driving environment in our lab, during which drivers wore the sensor necklace. These experiments demonstrate the reliability of the wearable sensor necklace in capturing dynamic changes in HR levels associated with driving-induced stress. The algorithms integrated into the sensor are optimized for low computational cost and effectively remove motion artifacts that occur when users move their heads. Full article
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<p>Block diagram of the developed sensor.</p>
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<p>PCB realization of the sensor: (<b>a</b>) top layer and (<b>b</b>) bottom layer. The sensing element, which comes into contact with the skin, is located exclusively on the bottom layer. (<b>c</b>) The necklace in its 3D printed case. The elastic band can be adjusted using a buckle.</p>
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<p>(<b>a</b>) Example of PPG and ECG waveform signals and their characteristic parameters; (<b>b</b>) example of PPG signals acquired by the necklace sensor from the R and IR channels.</p>
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<p>Raw data acquired from the R and IR channels. The peaks corresponding to heartbeats have a much smaller amplitude compared to the overall signal amplitude, as do the baseline and motion artifacts.</p>
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<p>Processed data for peak detection from the R channel—blue line: band-passed R data; red line: envelope detector; black markers: detected peaks.</p>
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<p>Flowchart of the algorithm implemented to extract the heart rate.</p>
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<p>Comparison between the reference heart rate (obtained from a simultaneous ECG) and the estimation results for Recording 5.</p>
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<p>A participant in the driving test scenario using our simulator.</p>
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<p>Comparison of reference heart rate (obtained from simultaneous ECG) and estimation results for Recording 12.</p>
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<p>Comparison of reference heart rate (obtained from simultaneous ECG) and estimation results for Recording 2.</p>
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<p>Comparison of reference heart rate (obtained from simultaneous ECG) and estimation results for Recording 9.</p>
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18 pages, 6050 KiB  
Article
Investigation of a Camera-Based Contactless Pulse Oximeter with Time-Division Multiplex Illumination Applied on Piglets for Neonatological Applications
by René Thull, Sybelle Goedicke-Fritz, Daniel Schmiech, Aly Marnach, Simon Müller, Christina Körbel, Matthias W. Laschke, Erol Tutdibi, Nasenien Nourkami-Tutdibi, Elisabeth Kaiser, Regine Weber, Michael Zemlin and Andreas R. Diewald
Biosensors 2024, 14(9), 437; https://doi.org/10.3390/bios14090437 - 9 Sep 2024
Viewed by 649
Abstract
(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 [...] Read more.
(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 nm and 940 nm) on a piglet model. (3) Results: Using this camera system and our newly designed algorithm for further analysis, the detection of a heartbeat and the calculation of oxygen saturation were evaluated. In motionless individuals, heartbeat and respiration were separated clearly during light breathing and with only minor intervention. In this case, the mean difference between noncontact and contact saturation measurements was 0.7% (RMSE = 3.8%, MAE = 2.93%). (4) Conclusions: The new sensor was proven effective under ideal animal experimental conditions. The results allow a systematic improvement for the further development of contactless vital sign monitoring systems. The results presented here are a major step towards the development of an incubator with noncontact sensor systems for use in the neonatal intensive care unit. Full article
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Graphical abstract
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<p>Molar absorption spectrum of hemoglobin and oxyhemoglobin based on Prahl [<a href="#B18-biosensors-14-00437" class="html-bibr">18</a>].</p>
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<p>Schematic representation of the light path from the transmitter through the skin and back to the receiver including remission and scattering as well as the path length <span class="html-italic">l</span> and the time-dependent path length <math display="inline"><semantics> <mrow> <mi>l</mi> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </semantics></math> in the artery. <math display="inline"><semantics> <msubsup> <mi>I</mi> <mi>λ</mi> <mi>i</mi> </msubsup> </semantics></math> means the intensity or power of the incident light and <math display="inline"><semantics> <msubsup> <mi>I</mi> <mi>λ</mi> <mi>t</mi> </msubsup> </semantics></math> means the intensity of the light escaping from the measuring medium. <math display="inline"><semantics> <msubsup> <mi>I</mi> <mi>λ</mi> <mi>r</mi> </msubsup> </semantics></math> means the power of reflected light.</p>
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<p>Time diagram of the LEDs for standard settings. The numbers indicate the clock cycles. During the first clock cycle, there is an empty measurement without any illumination; during the second cycle, the 660 nm LEDs are switched on; during the third cycle, the 810 nm LEDs; during the fourth cycle, the 660 nm LEDs again; during the fifth cycle, the 940 nm LEDs; and during the sixth cycle, the 660 nm LEDs again. Then the sequence repeats from the beginning.</p>
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<p>Undersampling diagram for expected background light frequencies over different sampling frequencies. Example: A 50 Hz modulated light (light blue color) results in 10 Hz (maximum) when sampled with 20 Hz, in 0 Hz when sampled with 25 Hz and in 16.6 Hz when sampled with 33.3 Hz. The selected sampling frequencies are chosen for 660 nm at 110 Hz (black line) and 810/940 nm at 36.67 Hz = 110/3 Hz in a manner that the undersampling frequencies of the modulated background light are out of the frequencies of interest.</p>
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<p>Block diagram of the algorithm used for the detection of a heartbeat and calculation of the oxygen saturation.</p>
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<p>(<b>A</b>) Number of LEDs per supply line and wavelength. (<b>B</b>) Arrangement of LEDs for lighting board. Numbers indicate the supply lines.</p>
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<p>Attenuation normalized to the intensity <math display="inline"><semantics> <msubsup> <mi>I</mi> <mi>λ</mi> <mi>i</mi> </msubsup> </semantics></math> for the wavelength of 940 nm on the target. The pixel pitch and pixel size is 5.3 μm.</p>
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<p>A screenshot (2) Figure seem to be cut on the top in a way that may affect scientific reading. Please check and provide whole image. of the measurement GUI including a picture of the piglet in the incubator with active illumination. The quadratic area is the area of interest (AOI) of 128 × 128 pixels for signal processing. The colors of the quadratic sub-areas have no additional meaning.</p>
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<p>Measurement setup: A piglet was placed in a NICU incubator. Pulse, oxygen saturation and respiration rate were measured by a camera-based contactless pulse oximeter which was placed on the incubator. For validation, an independent monitor, which is commonly used in neonatal intensive care units, was linked via a pulse oximeter sensor to the piglet leg together with a three-channel electrocardiograph. The red color in the incubator is caused by the active illumination of the SpO<sub>2</sub> sensor system and not from an infrared heating lamp, which would disturb the measurement. The camera and the illumination are mounted at the bottom side of the metallic box above the incubator and point into the incubator. The camera and the illumination are shown in the lower-left corner of the picture.</p>
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<p>Example measurement 1. Camera data showing a recording from the oxygen saturation sensor: Example of a cumulated spectrum with respiration superimposed onto the heartbeat (multiplex scheme see <a href="#biosensors-14-00437-f003" class="html-fig">Figure 3</a>).</p>
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<p>Example measurement 2. Camera data of a recording from the oxygen saturation sensor: Example of a cumulative spectrum with successful heartbeat detection (multiplex scheme see <a href="#biosensors-14-00437-f002" class="html-fig">Figure 2</a>). Heartbeat and respiration rate are clearly identifiable, as well as artifacts and respiratory interruptions.</p>
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<p>Bland– Altman diagram demonstrating the successful measurement of oxygen saturation of one piglet within a period of 20 min. This serves to compare the two measurement methods used.</p>
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<p>Time signals of oxygen saturation compare camera and monitor. Calculated according to <a href="#biosensors-14-00437-f011" class="html-fig">Figure 11</a>.</p>
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18 pages, 2308 KiB  
Article
Impact of a Precision Intervention for Vascular Health in Middle-Aged and Older Postmenopausal Women Using Polar Heart Rate Sensors: A 24-Week RCT Study Based on the New Compilation of Tai Chi (Bafa Wubu)
by Xiaona Wang, Yanli Han, Haojie Li, Xin Wang and Guixian Wang
Sensors 2024, 24(17), 5832; https://doi.org/10.3390/s24175832 - 8 Sep 2024
Viewed by 571
Abstract
(1) Background: This study utilized a 24-week intervention incorporating heart rate sensors for real-time monitoring of intervention training, aiming to comprehensively assess the effects of Tai Chi on vascular endothelial function, atherosclerosis progression, and lipid metabolism. The insights gained may inform personalized non-pharmacological [...] Read more.
(1) Background: This study utilized a 24-week intervention incorporating heart rate sensors for real-time monitoring of intervention training, aiming to comprehensively assess the effects of Tai Chi on vascular endothelial function, atherosclerosis progression, and lipid metabolism. The insights gained may inform personalized non-pharmacological interventions to enhance the management of cardiovascular health in this population to provide sustainable benefits and improve quality of life. (2) Methods: Forty postmenopausal middle-aged and elderly women were randomly assigned to an exercise or control group. The exercise group underwent a 24-week Tai Chi (BaFa WuBu) training intervention with real-time heart rate monitoring using Polar sensors. Pre- and post-intervention assessments included body composition, blood pressure, vascularity, and blood parameters measured with the Inbody 720, Vascular Endothelial Function Detector, and Arteriosclerosis. Data were analyzed using SPSS 26.0 and mixed-design ANOVA to assess the effects of time, group, and their interactions on study outcomes. (3) Results: After training through 24 weeks of Tai Chi (BaFa WuBu) intervention, compared with the control group, systolic blood pressure in the exercise group was significantly lower (p < 0.05), and the difference between left and right arm pulse pressure, left and right ankle mean arterial pressure, left and right side baPWV, left and right side ABI, TC, TG, LDL, and blood pressure viscosity were all very significantly lower (p < 0.01), and the diastolic blood pressure was significantly higher (p < 0.05). Compared with baseline values in the exercise group, systolic blood pressure, right and left arm pulse pressure difference, right and left ankle mean arterial pressure, right and left side baPWV, right and left side ABI, TC, TG, LDL, and blood pressure viscosity decreased very significantly (p < 0.01) and diastolic blood pressure and FMD increased very significantly (p < 0.01) in the exercise group after the intervention. (4) Conclusions: In our study, a 24-week Tai Chi (BaFa WuBu) program significantly improved vascular health in middle-aged and older postmenopausal women. This simplified Tai Chi form is gentle and effective, ideal for older adults. Regular practice led to reduced vascular obstruction, improved lipid metabolism, and enhanced vascular endothelial function, crucial for preventing vascular diseases. The real-time heart rate sensors used were pivotal, enabling precise monitoring and adjustment of exercise intensity, thereby enhancing the study’s scientific rigor and supporting Tai Chi (BaFa WuBu) as a beneficial therapeutic exercise. Full article
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<p>Polar heart rate sensor.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on systolic and diastolic blood pressure in middle-aged and elderly postmenopausal women, with the control group in blue and the exercise group in pink.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on pulse pressure difference in middle-aged and elderly postmenopausal women, control group in blue and exercise group in pink.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on mean arterial pressure in middle-aged and elderly postmenopausal women, blue is control group, pink is exercise group.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on vascular stiffness in middle-aged and older postmenopausal women. baPWV is the arm–ankle pulse wave conduction velocity and ABI is the ankle–brachial index; blue is the control group and pink is the exercise group.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on vascular endothelial function in middle-aged and older postmenopausal women, FMD is brachial artery flow-mediated vasodilatation function; control group in blue, exercise group in pink.</p>
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<p>Effects of 24 weeks of Tai Chi (BaFa WuBu) intervention on lipids in middle-aged and older postmenopausal women; TC is total cholesterol, TG is triglyceride, LDL is low-density lipoprotein, and HDL is high-density lipoprotein; blue is the control group and pink is the exercise group.</p>
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<p>Effect of 24 weeks of Tai Chi (BaFa WuBu) intervention on plasma viscosity in middle-aged and older postmenopausal women, control group in blue and exercise group in pink.</p>
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24 pages, 1914 KiB  
Article
Enhancing Elderly Care through Low-Cost Wireless Sensor Networks and Artificial Intelligence: A Study on Vital Sign Monitoring and Sleep Improvement
by Carolina Del-Valle-Soto, Ramon A. Briseño, Ramiro Velázquez, Gabriel Guerra-Rosales, Santiago Perez-Ochoa, Isaac H. Preciado-Bazavilvazo, Paolo Visconti and José Varela-Aldás
Future Internet 2024, 16(9), 323; https://doi.org/10.3390/fi16090323 - 6 Sep 2024
Viewed by 471
Abstract
This research explores the application of wireless sensor networks for the non-invasive monitoring of sleep quality and vital signs in elderly individuals, addressing significant challenges faced by the aging population. The study implemented and evaluated WSNs in home environments, focusing on variables such [...] Read more.
This research explores the application of wireless sensor networks for the non-invasive monitoring of sleep quality and vital signs in elderly individuals, addressing significant challenges faced by the aging population. The study implemented and evaluated WSNs in home environments, focusing on variables such as breathing frequency, deep sleep, snoring, heart rate, heart rate variability (HRV), oxygen saturation, Rapid Eye Movement (REM sleep), and temperature. The results demonstrated substantial improvements in key metrics: 68% in breathing frequency, 68% in deep sleep, 70% in snoring reduction, 91% in HRV, and 85% in REM sleep. Additionally, temperature control was identified as a critical factor, with higher temperatures negatively impacting sleep quality. By integrating AI with WSN data, this study provided personalized health recommendations, enhancing sleep quality and overall health. This approach also offered significant support to caregivers, reducing their burden. This research highlights the cost-effectiveness and scalability of WSN technology, suggesting its feasibility for widespread adoption. The findings represent a significant advancement in geriatric health monitoring, paving the way for more comprehensive and integrated care solutions. Full article
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<p>Summary of research on wireless sensor networks for monitoring sleep quality and vital signs in the elderly [<a href="#B4-futureinternet-16-00323" class="html-bibr">4</a>].</p>
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<p>Informed consent form for elderly participants in home sensor network research.</p>
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<p>A block diagram summarizing the WSN Development Kit, including network structure, communication protocols, hardware specifications, and power supply options.</p>
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<p>The implementation of the wireless sensor network.</p>
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<p>Sieve diagram for the variables deep sleep (DS) and snoring (S).</p>
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<p>Sieve diagram for the variables breathing frequency (BF) and snoring (S).</p>
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<p>Sieve diagram for the variables heart rate (HR) and temperature (T).</p>
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<p>Sieve diagram for the variables heart rate variability (HRV) and temperature (T).</p>
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25 pages, 1690 KiB  
Article
Correlations between Social Isolation and Functional Decline in Older Adults after Lower Limb Fractures Using Multimodal Sensors: A Pilot Study
by Faranak Dayyani, Charlene H. Chu, Ali Abedi and Shehroz S. Khan
Algorithms 2024, 17(9), 383; https://doi.org/10.3390/a17090383 - 1 Sep 2024
Viewed by 431
Abstract
Older adults (OAs) recovering from lower limb fractures experience social isolation (SI) and functional decline (FD) after they are discharged from inpatient rehabilitation due to reduced physical mobility. Our research used MAISON (Multimodal AI-based Sensor platform for Older iNdividuals), a multimodal sensor system [...] Read more.
Older adults (OAs) recovering from lower limb fractures experience social isolation (SI) and functional decline (FD) after they are discharged from inpatient rehabilitation due to reduced physical mobility. Our research used MAISON (Multimodal AI-based Sensor platform for Older iNdividuals), a multimodal sensor system comprising various smart devices collecting acceleration, heart rate, step count, frequency of indoor motion, GPS, and sleep metrics. This study aimed to investigate the correlations between SI and FD with multimodal sensor data from OAs following lower limb fractures. Multimodal sensor data from eight OAs (8 weeks per person) living at home were collected. Five clinical metrics were obtained via biweekly video calls, including three clinical questionnaires (Social Isolation Scale (SIS), Oxford Hip Score, Oxford Knee score) and two physical mobility assessments (Timed Up and Go, 30 s chair stand). From the sensor data collected, 53 statistical and domain features were extracted. Spearman correlation coefficients were calculated between the extracted features and clinical data. The results indicated strong correlations between various items of SIS and sleep metrics in OAs and various items of Oxford Knee Score with GPS and acceleration data. Strong correlations between the questions of the Oxford scores and sensor data highlight the direct impact of physical health status on measurable daily physical activities. Full article
(This article belongs to the Special Issue Artificial Intelligence Algorithms in Healthcare)
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<p>Block diagram of the MAISON platform for collecting multimodal data [<a href="#B29-algorithms-17-00383" class="html-bibr">29</a>].</p>
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<p>Line plot of 3 daily statistical features affected by fracture (top plot) and affected by all fractures (lower plot): (<b>a</b>) step-sum (total step count); (<b>b</b>) heart rate-mean (average heart rate from the smartwatch); and (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>l</mi> <mn>2</mn> </mrow> </semantics></math>-mean (average magnitude of acceleration). The gray line on each sub-figure indicates the trend line for the line plot.</p>
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<p>Line plot of 4 domain-specific daily features, affected by fracture (top plot) and affected by all fractures (lower plot): (<b>a</b>) distance traveled from home (km); (<b>b</b>) motion-sum (total number of motions per day); (<b>c</b>) total sleep duration; and (<b>d</b>) hr-average (average heart rate during sleeping episodes). The gray line on each sub-figure indicates the trend line for the line plot.</p>
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<p>Scatter plot of bi-weekly strong correlation between (<b>a</b>) SIS (Belonging) and total step count, (<b>b</b>) SIS (Belonging) and wake up count during sleep, (<b>c</b>) SIS (Belonging) and distance traveled from home.</p>
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<p>Scatter plot of bi-weekly strong correlation between (<b>a</b>) question 11 on Oxford Hip Score and average heart rate during sleep, (<b>b</b>) question 11 on Oxford Hip Score and average heart rate during the day, (<b>c</b>) question 11 on Oxford Hip Score and maximum heart rate during sleep. (bpm = beats per minute).</p>
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<p>SIS questionnaire.</p>
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11 pages, 3172 KiB  
Article
AI Asthma Guard: Predictive Wearable Technology for Asthma Management in Vulnerable Populations
by Hajar Almuhanna, Manayer Alenezi, Mariam Abualhasan, Shouq Alajmi, Raghad Alfadhli and Abdullah S. Karar
Appl. Syst. Innov. 2024, 7(5), 78; https://doi.org/10.3390/asi7050078 - 30 Aug 2024
Viewed by 607
Abstract
This paper presents AI Asthma Guard, a novel wearable device designed to predict and alert users of impending asthma attacks using artificial intelligence. The system integrates physiological and environmental sensors to monitor health metrics such as the heart rate, oxygen saturation, and exposure [...] Read more.
This paper presents AI Asthma Guard, a novel wearable device designed to predict and alert users of impending asthma attacks using artificial intelligence. The system integrates physiological and environmental sensors to monitor health metrics such as the heart rate, oxygen saturation, and exposure to specific air pollutants, which are crucial in managing asthma in children and individuals with mental disabilities. Utilizing machine learning models, including support vector machines and random forest, AI Asthma Guard classifies the risk levels of asthma attacks and provides timely notifications. This study details the device’s design, implementation, and preliminary testing results, underscoring its potential to improve health outcomes by enabling proactive asthma management. The implications of this technology reflect its alignment with the Sustainable Development Goals by enhancing individual health and well-being. The integration of a companion app leveraging large language models like ChatGPT facilitates user interaction, providing personalized advice and educational content about asthma management. Full article
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<p>Comparative analysis of scholarly publications on asthma and machine learning. The graph shows the total number of publications on asthma and machine learning in research, illustrating the trends and research interest over time (Source: Science Direct).</p>
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<p>System block diagram of the Asthma Guard management system. The diagram illustrates the flow from user interaction to severity assessment and active management.</p>
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<p>Confusion matrix of Classifier 2.</p>
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<p>Performance of the regression model, illustrating the observed and predicted smoke levels for the testing data.</p>
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<p>Circuit diagram. All sensors and outputs are connected to the microcontroller ESP32.</p>
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<p>Asthma Guard bracelet. The basic enclosure houses all of the components, with the sensors externally mounted. The debug window shown on the display is rendered in the figure inset.</p>
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20 pages, 272 KiB  
Article
Advancing mHealth Research in Low-Resource Settings: Young Women’s Insights and Implementation Challenges with Wearable Smartwatch Devices in Uganda
by Monica H. Swahn, Kevin B. Gittner, Matthew J. Lyons, Karen Nielsen, Kate Mobley, Rachel Culbreth, Jane Palmier, Natalie E. Johnson, Michael Matte and Anna Nabulya
Sensors 2024, 24(17), 5591; https://doi.org/10.3390/s24175591 - 29 Aug 2024
Viewed by 697
Abstract
In many regions globally, including low-resource settings, there is a growing trend towards using mHealth technology, such as wearable sensors, to enhance health behaviors and outcomes. However, adoption of such devices in research conducted in low-resource settings lags behind use in high-resource areas. [...] Read more.
In many regions globally, including low-resource settings, there is a growing trend towards using mHealth technology, such as wearable sensors, to enhance health behaviors and outcomes. However, adoption of such devices in research conducted in low-resource settings lags behind use in high-resource areas. Moreover, there is a scarcity of research that specifically examines the user experience, readiness for and challenges of integrating wearable sensors into health research and community interventions in low-resource settings specifically. This study summarizes the reactions and experiences of young women (N = 57), ages 18 to 24 years, living in poverty in Kampala, Uganda, who wore Garmin vívoactive 3 smartwatches for five days for a research project. Data collected from the Garmins included participant location, sleep, and heart rate. Through six focus group discussions, we gathered insights about the participants’ experiences and perceptions of the wearable devices. Overall, the wearable devices were met with great interest and enthusiasm by participants. The findings were organized across 10 domains to highlight reactions and experiences pertaining to device settings, challenges encountered with the device, reports of discomfort/comfort, satisfaction, changes in daily activities, changes to sleep, speculative device usage, community reactions, community dynamics and curiosity, and general device comfort. The study sheds light on the introduction of new technology in a low-resource setting and also on the complex interplay between technology and culture in Kampala’s slums. We also learned some insights into how wearable devices and perceptions may influence behaviors and social dynamics. These practical insights are shared to benefit future research and applications by health practitioners and clinicians to advance and enhance the implementation and effectiveness of wearable devices in similar contexts and populations. These insights and user experiences, if incorporated, may enhance device acceptance and data quality for those conducting research in similar settings or seeking to address population-specific needs and health issues. Full article
(This article belongs to the Special Issue Advances in Mobile Sensing for Smart Healthcare)
22 pages, 9117 KiB  
Article
Artificial Intelligence-Driven Prognosis of Respiratory Mechanics: Forecasting Tissue Hysteresivity Using Long Short-Term Memory and Continuous Sensor Data
by Ghada Ben Othman, Amani R. Ynineb, Erhan Yumuk, Hamed Farbakhsh, Cristina Muresan, Isabela Roxana Birs, Alexandra De Raeve, Cosmin Copot, Clara M. Ionescu and Dana Copot
Sensors 2024, 24(17), 5544; https://doi.org/10.3390/s24175544 - 27 Aug 2024
Viewed by 625
Abstract
Tissue hysteresivity is an important marker for determining the onset and progression of respiratory diseases, calculated from forced oscillation lung function test data. This study aims to reduce the number and duration of required measurements by combining multivariate data from various sensing devices. [...] Read more.
Tissue hysteresivity is an important marker for determining the onset and progression of respiratory diseases, calculated from forced oscillation lung function test data. This study aims to reduce the number and duration of required measurements by combining multivariate data from various sensing devices. We propose using the Forced Oscillation Technique (FOT) lung function test in both a low-frequency prototype and the commercial RESMON device, combined with continuous monitoring from the Equivital (EQV) LifeMonitor and processed by artificial intelligence (AI) algorithms. While AI and deep learning have been employed in various aspects of respiratory system analysis, such as predicting lung tissue displacement and respiratory failure, the prediction or forecasting of tissue hysteresivity remains largely unexplored in the literature. In this work, the Long Short-Term Memory (LSTM) model is used in two ways: (1) to estimate the hysteresivity coefficient η using heart rate (HR) data collected continuously by the EQV sensor, and (2) to forecast η values by first predicting the heart rate from electrocardiogram (ECG) data. Our methodology involves a rigorous two-hour measurement protocol, with synchronized data collection from the EQV, FOT, and RESMON devices. Our results demonstrate that LSTM networks can accurately estimate the tissue hysteresivity parameter η, achieving an R2 of 0.851 and a mean squared error (MSE) of 0.296 for estimation, and forecast η with an R2 of 0.883 and an MSE of 0.528, while significantly reducing the number of required measurements by a factor of three (i.e., from ten to three) for the patient. We conclude that our novel approach minimizes patient effort by reducing the measurement time and the overall ambulatory time and costs while highlighting the potential of artificial intelligence methods in respiratory monitoring. Full article
(This article belongs to the Special Issue Artificial Intelligence for Medical Sensing)
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<p>(<b>A</b>) Schematic of the 4P–FOT device’s principle of operation and related instrumentation. (<b>B</b>) RESMON Pro Full device.</p>
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<p>Schematic of the Equivital monitoring system.</p>
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<p>Upper graph: Illustration of the two-hour measurement protocol. Bottom: (<b>A</b>) Clinical setup comprising two FOT devices with their inputs and recorded signals. The RESMON Pro Full is a standalone device with two parts: the device (1) and an arm holder (2). It features a touchscreen display (3) for user interaction and a USB port (4) for data storage. The 4P-FOT device, used at lower frequencies, is mounted on an adjustable table (5) and is connected to a laptop (6) with built-in programs and a user interface. A single-use disposable mouthpiece (8) is connected to a slot (7) for each measurement. (<b>B</b>) The EQV real-time physiological signal monitoring sensor and the recorded signals.</p>
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<p>Schematic representation of the proposed AI algorithm for estimating <math display="inline"><semantics> <mi>η</mi> </semantics></math>.</p>
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<p>Schematic representation of the AI approach for estimating <math display="inline"><semantics> <mi>η</mi> </semantics></math>.</p>
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<p>The average correlation between impedance model parameters and physiological parameters measured by the EQV sensor across all individuals.</p>
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<p>Comparison of LSTM-estimated <math display="inline"><semantics> <mi>η</mi> </semantics></math> values with actual <math display="inline"><semantics> <mi>η</mi> </semantics></math> values for 10 measurements using the FOT device.</p>
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<p>Comparison of LSTM-estimated <math display="inline"><semantics> <mi>η</mi> </semantics></math> values with actual <math display="inline"><semantics> <mi>η</mi> </semantics></math> values for 10 measurements using the RESMON device.</p>
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<p>Comparison of LSTM-forecasted HR values with actual HR values for 10 measurements using the FOT device.</p>
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<p>Comparison of LSTM-forecasted HR values with actual HR values for 10 measurements using the RESMON device.</p>
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<p>Comparison of LSTM-forecasted <math display="inline"><semantics> <mi>η</mi> </semantics></math> values with actual <math display="inline"><semantics> <mi>η</mi> </semantics></math> values for 10 measurements using the FOT device.</p>
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<p>Comparison of LSTM-forecasted <math display="inline"><semantics> <mi>η</mi> </semantics></math> values with actual <math display="inline"><semantics> <mi>η</mi> </semantics></math> values for 10 measurements using the RESMON device.</p>
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<p>Comparison of real and estimated ECG Lead II signals for six volunteers using the EQV sensor. The estimated signal is in red, and the real signal is in blue.</p>
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<p>Electrode placement for ECG Lead I and Lead II, forming Einthoven’s triangle.</p>
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<p>Flowchart illustrating the estimation mechanism used to predict the tissue hysteresivity coefficient <math display="inline"><semantics> <mi>η</mi> </semantics></math>.</p>
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<p>Flowchart illustrating the forecasting mechanism used to predict the tissue hysteresivity coefficient <math display="inline"><semantics> <mi>η</mi> </semantics></math>.</p>
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20 pages, 15559 KiB  
Article
IoT-Based Assessment of a Driver’s Stress Level
by Veronica Mattioli, Luca Davoli, Laura Belli, Sara Gambetta, Luca Carnevali, Andrea Sgoifo, Riccardo Raheli and Gianluigi Ferrari
Sensors 2024, 24(17), 5479; https://doi.org/10.3390/s24175479 - 23 Aug 2024
Viewed by 510
Abstract
Driver Monitoring Systems (DMSs) play a key role in preventing hazardous events (e.g., road accidents) by providing prompt assistance when anomalies are detected while driving. Different factors, such as traffic and road conditions, might alter the psycho-physiological status of a driver by increasing [...] Read more.
Driver Monitoring Systems (DMSs) play a key role in preventing hazardous events (e.g., road accidents) by providing prompt assistance when anomalies are detected while driving. Different factors, such as traffic and road conditions, might alter the psycho-physiological status of a driver by increasing stress and workload levels. This motivates the development of advanced monitoring architectures taking into account psycho-physiological aspects. In this work, we propose a novel in-vehicle Internet of Things (IoT)-oriented monitoring system to assess the stress status of the driver. In detail, the system leverages heterogeneous components and techniques to collect driver (and, possibly, vehicle) data, aiming at estimating the driver’s arousal level, i.e., their psycho-physiological response to driving tasks. In particular, a wearable sensorized bodice and a thermal camera are employed to extract physiological parameters of interest (namely, the heart rate and skin temperature of the subject), which are processed and analyzed with innovative algorithms. Finally, experimental results are obtained both in simulated and real driving scenarios, demonstrating the adaptability and efficacy of the proposed system. Full article
(This article belongs to the Special Issue Robust Multimodal Sensing for Automated Driving Systems)
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<p>Experimental setup of the proposed DMS.</p>
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<p>Equivital EQ02 Life Monitor sensor: (<b>a</b>) belt, (<b>b</b>) SEM, and (<b>c</b>) positioning.</p>
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<p>FLIR One Pro LT thermal camera: (<b>a</b>) sensor connection, (<b>b</b>) positioning, and (<b>c</b>) recorded infrared frame.</p>
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<p>Data acquisition architecture of proposed DMS.</p>
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<p>Driving protocol adopted in realistic scenarios.</p>
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<p>Beltway (<b>a</b>,<b>c</b>) and urban (<b>b</b>) roads crossed in the city of Parma, Italy, during driving tests.</p>
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<p>Driving protocol adopted in simulated scenarios.</p>
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<p>Dedicated algorithm for thermal data processing.</p>
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<p>Samples of (<b>a</b>) original RGB and (<b>b</b>) processed thermal frames extracted during driving session <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>1</mn> </msub> </semantics></math>.</p>
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<p>Samples of (<b>a</b>) original RGB and (<b>b</b>) processed thermal frames extracted during driving session <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>2</mn> </msub> </semantics></math>.</p>
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<p>Physiological data extracted during (<b>a</b>) <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>1</mn> </msub> </semantics></math> and (<b>b</b>) <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>2</mn> </msub> </semantics></math>.</p>
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<p>(<b>a</b>) Mean temperatures and (<b>b</b>) normalized mean temperatures extracted during <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>1</mn> </msub> </semantics></math>.</p>
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<p>(<b>a</b>) Mean temperatures and (<b>b</b>) normalized mean temperatures extracted during <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>2</mn> </msub> </semantics></math>.</p>
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<p>Mean temperatures averaged over time windows corresponding to the epochs of the driving protocol for (<b>a</b>) <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>1</mn> </msub> </semantics></math> and (<b>b</b>) <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>2</mn> </msub> </semantics></math>.</p>
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<p>Experimental RMSSD (purple), experimental arousal (green, calculated each 5 s) and mean arousal (orange, calculated over each epoch) for scenario <math display="inline"><semantics> <msub> <mi mathvariant="script">S</mi> <mn>2</mn> </msub> </semantics></math>.</p>
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<p>Physiological data extracted during a real driving session.</p>
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