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The basic working principle of optical heart rate sensor

Update: 2019-08-19 15:05 Source: LUFTMY

First of all, let's look at what PPG is.In biomedical applications, PPG (photoplethysmograph) is a kind of infrared nondestructive testing technology, which uses photoplethysmograph technology to detect human motion heart rate.It uses photoelectric sensors to detect the different intensity of reflected light absorbed by human blood and tissues, record the volume change of blood vessels in the cardiac cycle, and then get the pulse waveform heart rate.

So, what is an optical heart rate sensor? The working principle of an optical heart rate sensor is that when the pulse rate or volume of blood changes, the light entering the human body will have a predictable scattering.

The optical heart rate sensor consists of:

Light emitter: It consists of two or more light emitting diodes, which mainly illuminate light into the skin.

Photodiode and Analog Front End: Capturing Refracted Light and Converting Analog Signal to Digital Signal.

Accelerometer: Measure motion, combine with optical signal, as input of PPG algorithm.

Algorithms: Processing signals from AFE and accelerometer, then superimposing them on PPG waveform to generate fault-tolerant heart rate data and other biometric data.

Optical heart rate sensor measurement field:

Respiratory rate: Data output of the respiratory rate of human movement and rest.

Blood oxygen level: The concentration of oxygen in blood can be measured.

Oxygen uptake: The maximum oxygen intake can be measured.

Heart rate variability: Blood pulse interval, also known as R-R interval, can be used as an indicator of pressure levels and different heart problems.

Cardiac efficiency: Cardiovascular and cerebrovascular health and physical condition indicators, measuring the power of the heart to do work.

Blood pressure: Measure blood pressure by PPG sensor signal.

Blood perfusion: It can track the changes of relative perfusion rate and blood perfusion level.

At the same time, optical heart rate sensor also brings many opportunities and challenges. Whether it can be improved and applied in photomechanics, whether it can correctly measure the correct results according to the different physiological structures of various parts, whether the algorithm can adapt to the impact of different environments, and so on, all need to be explored and verified one by one.

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