It is based on the principle that when a fixed wavelength light beam is irradiated to the surface of the skin, the light beam will be transmitted to the photoelectric receiver through the transmission or reflection method, and in the process, due to the attenuation caused by the absorption of the skin, muscle and blood, the intensity of the light detected by the detector will be weakened. The absorption of light by the skin and muscle tissue remains constant throughout the blood circulation, but the volume of blood within the skin is subject to pulsatile changes under the action of the heart.
When the heart contracts the peripheral blood volume is the largest, the light absorption is also the largest, and the detected light intensity is the smallest. The opposite is true when the heart is in diastole, where the intensity of light is detected to be the greatest, resulting in a pulsatile change in the intensity of light received by the light receiver.
Smart bracelet use precautions
Wear the bracelet on the wrist horizontal lines on the 2-inch Neiguan point, pay attention to the interface of the bracelet is toward their side, do not bring down. By walking naturally in this way, you can record various data.
While testing the heart rate, you need to stand still, chest and abdomen, relax, raise your arms to stay parallel to the chest position, keep the posture unchanged, you can see the interface of the bracelet is constantly changing, which shows the date, time, walking distance, steps, and finally heart rate and blood oxygen rate, until the interface is no longer changing on it.
After using it for a long time, we need to charge the bracelet, as long as the two copper pieces on the back of the body of the bracelet and the two copper buttons on the charger correspond to each other, you can connect the 5V charging head for charging, and the charging head of the cell phone can be used as well.
In principle it means that the sensor of the bracelet in contact with the skin will emit a beam of light hitting the skin and measure the reflected/transmitted light.
Because blood absorbs a specific wavelength of light, that wavelength is absorbed heavily each time the heart pumps blood, and in this way you can determine the heartbeat.
But the downside is that it consumes a lot of power and can be disturbed by ambient light. Most of the smart bracelets or watches on the market today that monitor heart rate use the photoelectric transmission measurement method.
Extended information
The construction of the bracelet
Smart bracelet body is generally made of medical rubber, memory rubber material. Natural and non-toxic, the appearance of the design of high-grade fashion, generous, not only with the function of sports and health secretary, but also with the function of fashion accessories, the appearance of streamlined wreaths, a variety of colors.
The ends are equipped with silver-colored coated metal caps, perfect for wearing, which makes it different from traditional bracelets with card locks or buttons.
Inside the smart bracelet is a lithium-ion battery that lasts up to 10 days, a vibration motor and a motion-sensing accelerometer. A small silver cap at the end of the bracelet serves as a button for changing settings, and another section has a 3.5-millimeter plug for connecting to a cell phone.
Reference:
Huawei ar measuring heart rate what principle
Principle is as follows:
The use of light transmission or reflection of blood flowing in the blood vessels (pulse) to detect the pulse rate, which is usually equal to the heart rate. The vast majority of bracelets currently use this principle to detect heart rate, also known as the photoelectric method.
Currently, most smart bracelet heart rate monitoring methods use the photoelectric method, and their distinctive feature is that the sensor part is equipped with a green LED light.
The method of measuring heart rate is simply based on the principle of light absorption, through the smart wearable device green LED light with light-sensitive photodiode irradiation of blood vessels for a period of time, because the blood is red, it can reflect the red light to absorb and receive green light, in the heart beat, the blood flow increases, the amount of absorption of green light will be bigger; in the heart beat gap when the blood flow will be reduced, the absorption of green light will also be bigger; the blood flow will be reduced, the absorption of green light will also be bigger.
Thus, heart rate can be measured based on the absorbance of blood.
What principle does the smart bracelet rely on to detect heartbeat
Author: Zhihu user
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Source: Zhihu
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Generally speaking, the principle of heart rate monitoring is usually divided into three kinds: one is the photoelectric transmission measurement method, which in principle means that the sensor of the bracelet in contact with the skin will emit a beam of light hitting the skin, and measure the reflected/transmitted light. Because blood absorbs a specific wavelength of light, every time the heart pumps blood, that wavelength is absorbed in large quantities, and in this way the heartbeat can be determined. The downside, however, is that it consumes a lot of power and can be interfered with by ambient light. Most of the smart bracelets or watches on the market today that monitor heart rate use the photoelectric transmission measurement method.
There is another way to test the ECG signal method, the sensor of the bracelet can determine the user's heart rate by measuring the electrical signal of the contraction of the heart muscle, the principle is similar to the principle of ECG. The disadvantage is that the circuit is more complex, occupies more PCB space, is susceptible to electromagnetic interference, while the sensor must be close to the skin, placed in a relatively fixed position, so it is difficult to have a bracelet to use this measurement method.
On top of that, there's vibration measurement, which has only recently come out. Because each heartbeat will cause the body to vibrate, through high-precision sensors to capture this vibration, and then after signal processing can get the heartbeat, in general, smart cushion or smart massager products will be used in this measurement method, the bracelet is relatively rare.
The principle of heart rate measurement of the Xiaomi bracelet is:
1. Detecting the oxygen content of human erythrocytes through the principle of reflection
2. Calculating the time difference between the ECG detection and the pulse detection by detecting the rate of pulse conduction in order to get the information of blood pressure
3. Getting a more accurate human body temperature through the temperature sensing on the inner and outer sides
4.4. Through the metabolic heat integration method, after detecting the metabolic growth of heat, blood oxygen saturation, blood flow rate, calculate the blood
sugar concentration value
The biggest breakthrough of this principle is to realize the non-invasive of the physical signs data obtained, with little interference to the person. Blood pressure, blood glucose, body
Temperature change value respectively for high blood pressure patients, diabetic patients, pregnant women, these categories of people to detect their own body data will be very helpful.
Note: The content is extracted from the network