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sensors:ppg [2022/03/22 22:13] – monahedayatisensors:ppg [2022/03/22 22:31] – monahedayati
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-====== Photoplethysmography (PPG) ======+ 
 +====== Photoplethysmography (PPG)====== 
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 +====== Overview ====== 
  
 The Photoplethysmography (PPG) also known as Blood Volume Pulse (BVP) is a non-invasive, low-cost biosignal sensor predominantly used in medical and psychophysiological settings to measure the heart rate. In the former case, it is used as a transportable (mobile or wearable) alternative to Electrocardiograms (ECG) outside of clinical settings, whereas in the latter it is often used in biofeedback, a technique to gain awareness and control over physiological functions that affect mental or neurobiological conditions. Furthermore, the Heart Rate Variable (HRV) derived from PPG signal can be effectively used as an indicator for emotion recognition most effectively alongside other biosignals such as EDA, EMG, or respiration sensing. Alongside other biosignal sensing devices, PPG has also been used in artistic audiovisual installations, typically collecting sensor data from an audience to create an evolving installation environment.  The Photoplethysmography (PPG) also known as Blood Volume Pulse (BVP) is a non-invasive, low-cost biosignal sensor predominantly used in medical and psychophysiological settings to measure the heart rate. In the former case, it is used as a transportable (mobile or wearable) alternative to Electrocardiograms (ECG) outside of clinical settings, whereas in the latter it is often used in biofeedback, a technique to gain awareness and control over physiological functions that affect mental or neurobiological conditions. Furthermore, the Heart Rate Variable (HRV) derived from PPG signal can be effectively used as an indicator for emotion recognition most effectively alongside other biosignals such as EDA, EMG, or respiration sensing. Alongside other biosignal sensing devices, PPG has also been used in artistic audiovisual installations, typically collecting sensor data from an audience to create an evolving installation environment. 
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 ====== Background ====== ====== Background ======
  
-Background+
 The term photoplethysmography was first introduced by Alrick Herzman and colleagues from the Department of Physiology at St. Louis University School of Medicine in the 1930s as “photoelectric plethysmography” based on the principle of light absorption by transilluminated tissue which varies based on the blood content. In 1938, Hertzman performed a validation of his PPG method comparing blood volume changes with measurements taken simultaneously by mechanical plethysmography. He then contended that a good skin contact for this method is required but without a pressure that can cause blanching of the site of measurement. He further concluded that sensor displacement can affect the measurement accuracy. But it was not until the development of pulse oximeter in the 1970s to measure patients’ blood oxygen saturation that a major advancement in clinical use of PPG was introduced which led to developments in computer-based digital signal processing and analysis. The term photoplethysmography was first introduced by Alrick Herzman and colleagues from the Department of Physiology at St. Louis University School of Medicine in the 1930s as “photoelectric plethysmography” based on the principle of light absorption by transilluminated tissue which varies based on the blood content. In 1938, Hertzman performed a validation of his PPG method comparing blood volume changes with measurements taken simultaneously by mechanical plethysmography. He then contended that a good skin contact for this method is required but without a pressure that can cause blanching of the site of measurement. He further concluded that sensor displacement can affect the measurement accuracy. But it was not until the development of pulse oximeter in the 1970s to measure patients’ blood oxygen saturation that a major advancement in clinical use of PPG was introduced which led to developments in computer-based digital signal processing and analysis.
  
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 There are several factors that can alter the PPG recordings that can be classified as sensing architecture, biological, and cardiovascular factors outlined in the table below. There are several factors that can alter the PPG recordings that can be classified as sensing architecture, biological, and cardiovascular factors outlined in the table below.
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