Monitoring heart rate measurement methods are: blood oxygen method, photoplethysmography, ECG signal method, arterial pressure method, and signal analysis method.
1. Blood oxygen method
SpO2 is the kind that is clipped at the tip of the index finger. Generally speaking, a complete oximeter often has two types of light-emitting diodes, one with a wavelength of 660 nm, which is red light of visible light, and one with a wavelength of more than 900 nm, which is infrared light. The oxygen-carrying hemoglobin and the non-oxygen-carrying hemoglobin in the blood vessels have different absorption rates for the two types of light.
The advantage of the blood oxygen method is to provide two signals of heart rate and blood oxygen saturation. The disadvantage is that the transmitted light signal needs to be received at the other end, so this part of the human tissue must be thin enough, and the only suitable positions on the whole body are the fingertips and earlobes. The wrist is too thick, visible light cannot penetrate at all, and the range of use is relatively limited.
2. Photovoltaic volume method
This is tracking the reflection of visible light (green light) in human tissue. Usually there are two green LEDs that emit visible light to the wrist, and then a photo sensor in the middle senses the reflected light. The reflection of light by skin, bones, meat, and fat of the human body is a fixed value, while the reflection of light by capillaries and arterial veins is a fluctuating value because the pulse volume keeps getting bigger and smaller. The frequency of this fluctuation is the pulse, which is generally consistent with the heart rate.
3. ECG signal method
The sinoatrial node rhythmically controls systole and diastole to pump blood to the trunk. This control signal is an electrical signal (the human nerve signal is expressed as an electrical signal on the nerve), which will gradually spread to the body surface and can be measured by electrodes on the skin. The electrocardiograph uses this principle. This rhythm is the heart rate. In addition, the ECG signal can also provide a lot of reference information for doctors to diagnose.
4. Arterial blood pressure method
This is the oldest method, the pulse diagnosis of Chinese medicine. The pressure in the arteries, which can be felt through the skin on either side of the wrist or neck, fluctuates regularly. This signal can be turned into a heart rate by means of a pressure sensor.
5. Signal analysis method
The human face is captured by ordinary natural light for 5s to 30s through ordinary cameras, and weak periodic signals are extracted from the captured light under the blessing of artificial intelligence;
Through biological radar waves, the fluctuations and changes of the human body surface are monitored, and with the blessing of artificial intelligence, the signals are separated to obtain weak periodic signals;
Through the pressure film sensor, the pressure monitoring of the fluctuation of the human body surface is indirectly carried out. With the blessing of artificial intelligence, the signal is separated to obtain a weak periodic signal.
All three methods can obtain weak periodic signals and analyze key indicators such as heart rate, blood pressure, blood oxygen, and respiration.
The free heart rate app “Heart Rate“:
IOS version: Heart Rate Monitor-Plus1Health on the App Store (apple.com)
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