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Two-Pronged Motion Artifact Reduction for Wearable Photoplethysmographic Biosensors
摘要： Motion artifact poses a big challenge in photoplethysmography (PPG) for it greatly increases the difficulties of extracting the signal of interest accurately and reliably. Various techniques have been put forward in the past to tackle the issue. While these techniques have focused exclusively on artifact reduction, we attack the problem on two fronts. By integrating the auxiliary sensor and exploiting its correlations with the optical PPG sensor, not only do we cancel the artifacts but also, at the same time, enhance the signal of interest. Enhancing the signal of interest equivalently boosts the artifact reduction. The experiments have shown that the strategy performs rather effectively: The 95% limits of agreement (LOA) after the artifact reduction has been reduced down to less than one third of the LOA before the artifact reduction and is only three fourths as much as that of the artifact-free PPG.
关键词： biological sensors,Sensor systems,photoplethysmography (PPG),motion artifacts
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rome, Italy (2018.6.11-2018.6.13)] 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Feasibility of Photoplethysmography Imaging of the Sole of the Foot
摘要： In photoplethysmography imaging the blood volume pulse is extracted from subtle skin color variations recorded with a camera. In most works, the camera is oriented towards the face or the palm of the hand. Recently, it has been shown that applying contact force to the skin, e.g. through contact with a glass plate, increases signal strength. However, this approach is prohibitive for the face and there are applications where the hands are not accessible. In this paper, we address this issue by applying photoplethysmography imaging to the sole of the foot, which is placed on a glass plate and exposed to controlled illumination. We investigate (1) whether this setup acquires signals with an adequate signal-to-noise ratio and (2) whether the feet can be used as a replacement for the more commonly used hands. Additionally, we analyze (3) whether using a carefully selected pixel subset instead of all pixels improves signal-to-noise ratio. We report on experimental data from N=21 healthy subjects that we make publicly available1. We applied photoplethysmography imaging to the sole of the foot and the palm of the hand and used a commercial ?nger photoplethysmography unit as ground truth. It is problematic that there is no established best practice for signal-to-noise estimation in PPGi research; hence we use ?ve different metrics with three from literature. Additionally, we compare the agreement of these metrics using the experimental data. Our results show that (1) the proposed setup acquires signals with an adequate signal-to-noise ratio, (2) using all pixels from foot videos results in slightly inferior performance compared to the hand, but (3) using pixel subsets improves signal quality at the foot to the level of the hand. These results pave the way for the development of a photoplethysmography imaging setup applied at the sole of the foot for different medical applications.
关键词： photoplethysmography imaging,blood volume pulse,signal-to-noise ratio,medical applications,pixel subset
更新于2025-09-09 09:28:46
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Photoplethysmography in dogs and cats: a selection of alternative measurement sites for pet monitor
摘要： Objective: Photoplethysmography (PPG) is an increasingly popular health and well-being tool for monitoring heart rate and oxygen saturation. Due to pigmentation and hairiness of dogs and cats, a pulse oximeter is routinely placed solely on the tongue. As this approach is feasible only for the pet monitor use during surgical procedures, we investigate PPG signal quality on several other measurement sites that would be better tolerated by conscious animals. Approach: Acquired PPG signals are analyzed by four signal quality indices (SQI): mean baseline, signal power, kurtosis, and tolerance score. Main Results: In dogs, the metacarpus and tail can substitute for oral pulse oximeter placement since both measurement sites exhibited high PPG signal kurtosis and were considered well-tolerated. In cats, the digit could be used with some limitations. Significance: Pet monitors with pulse oximeter probes adjusted to promising measurement sites, could enable veterinarians and owners to monitor animals when fully awake.
关键词： pet monitor,motion artifact,veterinary medicine,oxygen saturation,heart rate,pulse oximeter,signal quality index,photoplethysmography
更新于2025-09-09 09:28:46
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Effects of Skin Surface Temperature on Photoplethysmograph
摘要： Photoplethysmograph (PPG) has been widely used to investigate various cardiovascular conditions. Previous studies demonstrated effects of temperature of the measurement environment; however, an integrated evaluation has not been established in environments with gradual air temperature variation. The purpose of this study is to investigate variations and relationships of blood pressure (BP), PPG and cardiovascular parameters such as heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR), by changing skin surface temperature (SST). Local mild cooling and heating was conducted on 16 healthy subjects. The results showed that local SST changes affected Finometer blood pressures (Finger BP), PPG components and TPR, but not the oscillometric blood pressure (Central BP), HR, SV and CO, and indicated that temperature must be maintained and monitored to reliably evaluate cardiovascular conditions in temperature-varying environments.
关键词： skin surface temperature,Photoplethysmography,vasodilation,local cooling and heating,vasoconstriction,cardiovascular status
更新于2025-09-09 09:28:46
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A Portable, Wireless Photoplethysomography Sensor for Assessing Health of Arteriovenous Fistula Using Class-Weighted Support Vector Machine
摘要： A portable, wireless photoplethysomography (PPG) sensor for assessing arteriovenous fistula (AVF) by using class-weighted support vector machines (SVM) was presented in this study. Nowadays, in hospital, AVF are assessed by ultrasound Doppler machines, which are bulky, expensive, complicated-to-operate, and time-consuming. In this study, new PPG sensors were proposed and developed successfully to provide portable and inexpensive solutions for AVF assessments. To develop the sensor, at first, by combining the dimensionless number analysis and the optical Beer Lambert’s law, five input features were derived for the SVM classifier. In the next step, to increase the signal-noise ratio (SNR) of PPG signals, the front-end readout circuitries were designed to fully use the dynamic range of analog-digital converter (ADC) by controlling the circuitries gain and the light intensity of light emitted diode (LED). Digital signal processing algorithms were proposed next to check and fix signal anomalies. Finally, the class-weighted SVM classifiers employed five different kernel functions to assess AVF quality. The assessment results were provided to doctors for diagonosis and detemining ensuing proper treatments. The experimental results showed that the proposed PPG sensors successfully achieved an accuracy of 89.11% in assessing health of AVF and with a type II error of only 9.59%.
关键词： support vector machine (SVM),arteriovenous fistula (AVF),photoplethysmography (PPG) sensor
更新于2025-09-09 09:28:46
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Effect of increasing heart rate on finger photoplethysmography fitness index (PPGF) in subjects with implanted cardiac pacemakers
摘要： Finger photoplethysmography (PPG) is a noninvasive method that measures blood volume changes in the finger. The PPG fitness index (PPGF) has been proposed as an index of vascular risk and vascular aging. The objectives of the study were to determine the effects of heart rate (HR) on the PPGF and to determine whether PPGF is influenced by blood pressure (BP) changes. Twenty subjects (78±8 years, 3 female) with permanent cardiac pacemakers or cardioverter defibrillators were prospectively recruited. HR was changed by pacing, in a random order from 60 to 100 bpm and in 10 bpm increments. At each paced HR, the PPGF was derived from a finger photoplethysmogram. Cardiac output (CO), stroke volume (SV) and total peripheral resistance (TPR) were derived from the finger arterial pressure waveform. Brachial blood pressure (BP) was measured by the oscillometric method. This study found that as HR was increased from 60 to 100 bpm, brachial diastolic BP, brachial mean BP and CO were significantly increased (p<0.01), whilst the PPGF and SV were significantly decreased (p<0.001). The effects of HR on the PPGF were influenced by BP, with a decreasing HR effect on the PPGF that resulted from a higher BP. In conclusion, HR was a significant confounder for PPGF and it must be taken into account in analyses of PPGF, when there are large changes or differences in the HR. The magnitude of this effect was BP dependent.
关键词： blood pressure,vascular aging,photoplethysmography,heart rate,PPG fitness index
更新于2025-09-09 09:28:46
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Approximation-Based Transformation of Color Signal for Heart Rate Estimation with a Webcam
摘要： Photoplethysmography (PPG) is a method for contactless heart rate estimation through the analysis of slight variations of skin color. Skin color variation caused by changes in the blood volume in vessels and registered by a camera is called color signal. Recent studies proved that some PPG methods could be used to produce accurate heart rate estimations on videodata recorded by common web-cameras that makes them potentially applicable for longterm health monitoring in home or office conditions. In this work, we study novel Approximation-based transformation method of signal processing and evaluate its combination with common preprocessing and postprocessing algorithms. Approximation-based transformation is the procedure of computing an approximation signal that consists of leading coefficients of the local quadratic approximation of the color signal.
关键词： signal processing,color signal,remote photoplethysmography,heart rate evaluation
更新于2025-09-09 09:28:46
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - A 5-ms Error, 22-μA Photoplethysmography Sensor using Current Integration Circuit and Correlated Double Sampling
摘要： This paper presents a low-power Photoplethysmography (PPG) sensing method. The PPG is commonly used in recent wearable devices to detect cardiovascular information including heartbeat. The heartbeat is useful for physical activity and stress monitoring. However, the PPG circuit consumes large power because it consists of LED and photodiode. To reduce its power consumption without accuracy degradation, a cooperative design of circuits and algorithms is proposed in this work. A straightforward way to reduce the power is intermittent driving of LED, but there is a disadvantage that the signal is contaminated by a noise while circuit switching. To overcome this problem, we introduce correlated double sampling (CDS) method, which samples an integration circuit output twice with short intervals after the LED turns on and uses the difference of these voltage. Furthermore, an up-conversion method using linear interpolation, and an error correction using autocorrelation are introduced. The proposed PPG sensor, which consists of the LED, the photodiode, the current integration circuit, a CMOS switch, an A/D converter, and an MCU, is prototyped. It is evaluated by actual measurement with 22-year-old subject. The measurement results show that 22-μA total current consumption is achieved with 5-ms mean absolute error.
关键词： wearable devices,low-power,heartbeat monitoring,Photoplethysmography (PPG),autocorrelation,correlated double sampling (CDS)
更新于2025-09-04 15:30:14
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Accurate Heart Rate Monitoring Method During Physical Exercise from Photoplethysmography Signal
摘要： Photoplethysmography (PPG) is mainly used to ?nd skin blood ?ow. Volumetric change of blood ?ow indicates cardiac rhythm, due to that there is a possibility to monitor the heart rate (HR) from PPG signals. PPG sensors can be implemented in wrist band or smart watch. HR monitoring during physical exercise can give helpful information regarding physical ?tness tracking features like calorie measurement, sleep tracking, counting steps and help the trainer to achieve their training goals. Body movements during physical exercise produces noise content in PPG signal. This noise content is generally called as moving artifact (MA). Monitoring accurate heart rate from PPG signal is a challenging task. Nowadays there are many methods are proposed to improve the HR monitoring from PPG signals. This work is envisaged to develop a method to detect accurate HR without any complexity. The proposed work consists of two steps (i) extraction of PPG signal from the observed PPG by sparse method, (ii) HR estimation. The main advantage of sparse method is the proper reconstruction of signals from small number of highly noisy elementary signals. This method eliminates the need of accelerometer reading and uses only two PPG signals, which results less complexity. Estimation of HR through the phase information, which provided by the polar representation of PPG signal. The proposed method results in an average absolute error of 1.00 BPM and average relative error of 0.85 BPM using 2 PPG signals compared to existing methods.
关键词： Photoplethysmography (PPG),motion artifacts (MA),heart rate (HR),sparse signal extraction
更新于2025-09-04 15:30:14
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A Novel Personalized Motion and Noise Artifact (MNA) Detection Method for Smartphone Photoplethysmograph (PPG) Signals
摘要： Photoplethysmography (PPG) is a technique to detect blood volume changes in an optical way. Representative PPG applications are the measurements of oxygen saturation, heart rate, and respiratory rate. However, the PPG signals are sensitive to motion and noise artifacts (MNAs), especially when they are obtained from smartphone cameras. Moreover, the PPG signals are different among users and each individual’s PPG signal has a unique characteristic. Hence, an effective MNA detection and reduction method for smartphone PPG signals, which adapts itself to each user in a personalized way, is highly demanded. In this paper, a concept of the probabilistic neural network is introduced to be used with the proposed extracted parameters. The signal amplitude, standard deviation of peak to peak time intervals and amplitudes, along with the mean of moving standard deviation, signal slope changes, and the optimal autoregressive model order are proposed for effective MNA detection. Accordingly, the performance of the proposed personalized algorithm is compared with conventional MNA detection algorithms. As for the performance metrics, we considered accuracy, sensitivity, and speci?city. The results show that the overall performance of the personalized MNA detection is enhanced compared to the generalized algorithm. The average values of the accuracy, sensitivity, and speci?city of the personalized one are 98.07%, 92.6%, and 99.78%, respectively, while these are 89.92%, 84.21%, and 93.63% for the general one.
关键词： photoplethysmography (PPG),Personalization,motion noise artifacts,signal quality index
更新于2025-09-04 15:30:14