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PPG-Based Biometric Recognition
Published in Gaurav Jaswal, Vivek Kanhangad, Raghavendra Ramachandra, AI and Deep Learning in Biometric Security, 2021
Photoplethysmograph, made up of photo (light) plus two Greek words plethysmos (increasing) and graph (write), is an optical instrument through which the changes in the blood volume can be detected and measured. This non-invasive method also known as photoelectric plethysmography was introduced by Alrick Hertzman in late 1930s. The signal acquired by using this instrument is called photoplethysmogram (PPG). A PPG signal is captured using an optical sensor, emitting red and infrared light, placed on the fingertip, earlobe, toe-tip, etc., with the first two acquisition sites being more popular and convenient. PPG signal shows the change in the volume of blood at the site of acquisition (fingertip) as the heart pumps the blood to various extremities. As shown in Figure 13.2, PPG pulse comprises of two waves: one systolic and the other diastolic wave [3].
Pervasive Computing and Ambient Physiological Monitoring Devices
Published in Bruno Bouchard, Smart Technologies in Healthcare, 2017
Sung Jae Isaac Chang, Jennifer Boger, Jianfeng Qiu, Alex Mihailidis
Photoplethysmogram (PPG) is a physiological signal that refl the oscillation of the blood volume in the vascular system (i.e. blood vessels) due to heart activity. During the systolic phase of the cardiac cycle, which is immediately after the ventricles contract to send blood throughout the body, the blood is pushed through the arteries and the amount of blood in the vascular system increases. Following the systole, the blood fills the heart chambers and the heart readies for the next contraction. In this phase, the amount of the blood present in the vascular system becomes relatively less. It is difficult and requires invasive methods to measure this change of blood volume in the arteries. The change of the blood volume in the capillary beds, on the contrary, is reflected to the skin and can be detected using appropriate tools. This detection of blood-volume change in capillary beds using a non-invasive sensor is called PPG. PPG provides the heart rate as well as the oxygen saturation level, which is defined as how much oxygen is being carried by the blood at the time of measurement.
Heart Rate Variability Analysis in Frequency Domain
Published in Mesut Sahin, Howard Fidel, Raquel Perez-Castillejos, Instrumentation Handbook for Biomedical Engineers, 2020
Mesut Sahin, Howard Fidel, Raquel Perez-Castillejos
The study of HRV requires equipment that is capable of recording the heartbeat continuously for some periods of time (for example, detection of VLF in HRV requires recordings of at least 24 h) and without causing distress to the subject under study. The simplest device available for studying HRV is the photoplethysmograph (PPG), which uses light to detect the changes in volume caused by the cardiac cycle in tissues highly permeated by blood capillaries such as fingertips, toes, or ear lobes (see Studio 8). It is worth noting that ECGs typically provide more detailed information of the heartbeat than the PPG, which may be necessary for complex diagnosis of patients with arrhythmias.
A wearable heart rate monitoring system based on over-ear headphones
Published in Journal of Medical Engineering & Technology, 2022
Andrii Voropai, Volodymyr Sarana
The need of monitoring basic hear rate spurred the development of a large number of wearable sensors and devices with a limited ECG functionality. Most of these devices are based on alternative heart activity monitoring methods such as the photoplethysmogram (PPG). These alternative methods are indirect ways of registering heart activity, they can’t provide ECG level accuracy [5]. Nevertheless, these methods are widely used for an active way of life, fitness and sleep tracking in a number of wearable electronics such as smart watches, armbands and chest straps. In recent years the ECG has been used in commercial wrist wearable devices like Apple Watch S4–S7, Samsung Galaxy Watch 3–4, Fitbit Sense and SenceBand. Taking an ECG on these devices requires a user’s certain actions and both hands to create an electrical circuit (except for SenceBand) to be able to record electrical activity of a heart. Another problem with this kind of wearable devices is a limited battery life, in most cases, they have to be removed from a wrist to a docking station to be charged and placed back to a wrist for another day or two. So, it is quite easy to forget a gadget on a charging station.
An Automated Algorithm to Extract Time Plane Features from the PPG Signal and its Derivatives for Personal Health Monitoring Application
Published in IETE Journal of Research, 2022
Abhishek Chakraborty, Deboleena Sadhukhan, Madhuchhanda Mitra
Photoplethysmogram (PPG) signal is used to detect relative blood volume changes in the peripheral body sites (i.e. finger tip, earlobe, and toe). Contemporary PPG acquisition module uses a light emitting diodes (LED) to illuminate the tissues and a photodiode to measure the amount of reflected or transmitted light [5]. Inherently, PPG signal consist of a pulsatile ac component (signifies average blood volume change) superimposed on a quasi-dc component (representing respiration and sympathetic nervous activity etc.), as shown in Figure 1(a). The onset of each pulse indicates the commencement of blood ejection from the heart to the aorta. The end of ejection is manifested in the form of dicrotic notch, indicating closure of the aortic valve [5].
Effectiveness of smart wrist wearables for distinguishing physical and cognitive demands
Published in IISE Transactions on Healthcare Systems Engineering, 2023
Jackie S. Cha, Fajar Ausri, Laura Mudge, Denny Yu
One wrist-worn wearable device and two reference-standard devices were used in this study. The wrist-worn device (E4, Empatica, Cambridge, MA, USA) measured HRV and EDA, and this specific device was chosen due to its prevalence in the literature (Jebelli et al., 2019; Koskimäki et al., 2017; Ragot et al., 2017; Regalia et al., 2019). Following manufacturer instructions, this wearable was placed on the non-dominant hand. Sensors embedded in this wearable included a photoplethysmogram (PPG) sensor to measure blood volume pressure. It also measured EDA using a sensor comprised of two silver electrodes that made contact on the palmar side of the non-dominant wrist (Figure 1). Raw data exported from the device included the interbeat interval (IBI; ms) and EDA (µS at 4 Hz).