How Do Smart Watch Monitor Heart Rate?

Smart watch with heart rate monitor

Heart rate, how important is it? It can be said that "heart rate is the key to everyone's health", when going to the hospital, the doctor must check the vital signs including heart rate. However, we often ignore it in daily life and only think about it when we are sick and in hospital. Fortunately, as the concept of healthy living has become more popular, people are becoming more aware of the importance of heart rate.

During exercise and fitness, even non-professional athletes will use heart rate equipment to understand their performance, use heart rate training method to guide training, improve their performance, and avoid sports injuries.

In daily life, many people use heart rate monitoring devices to understand their physical condition, and these data are based on the heart rate to calculate. For example, the BP smartwatch has all-day pressure monitoring, sleep monitoring, blood oxygen saturation and other functions.

As we all know, in the daily life to find changes in the body, is a very important part of the prevention of physical diseases. So, there are people who use heart rate devices for warning. For example, some devices can set a heart rate alert that will alert the wearer to take action when the heart rate exceeds the maximum set heart rate.

So, besides going to the hospital, how else can we measure heart rate?

In general, there are three convenient methods: pulse measurement, ECG signal method and photoelectric volume method. Today, we're going to talk a little bit.


smart watch with heartbeat sensor


BP smart watch:Through innovative optical path structure design, combined with intelligent heart rate algorithm, completes the heart rate monitoring and early warning, high heart rate throughout the fast and accurate, comprehensive evaluate the working condition of the heart, your health, need to know.

1. Pulse measurement method

Under normal conditions, the heart rate and pulse rate are the same, and the pulse measurement method is similar to the traditional Chinese medicine method of pulse detection. Usually, the pulse can be measured in large arteries located superficial to the bones of the body. In order to facilitate the operation, the radial artery, carotid artery, brachial artery these suitable measurement sites can be selected.

Radial artery pulse point (wrist) : located inside the radial side (thumb side) of the wrist.

Carotid pulse point (neck) : The CAROTID pulse can be touched in the depression between the trachea and the medial sternocleidomastoid muscle.

Brachial artery pulse point (arm) : The brachial artery pulse point is located in the cubital fossa, between the biceps and triceps.

In the measurement, keep calm, index finger and middle finger together, the tip of the finger lightly press the measurement site, record the pulse rate in 15-30 seconds, so as to calculate their heart rate per minute.
It should be noted that the first method has two obvious drawbacks: one is the large error, such as irregular heartbeat or other heart diseases.Second, it is difficult to operate in motion.

So, how can you measure heart rate more easily during exercise?

In recent years, various manufacturers have incorporated heart rate monitoring functions into consumer sports equipment through ECG signals and photoelectric volume methods. The main product forms include heart rate bands, watches and wristbands.

2, ECG signal method

Heart rate band is the most accurate wearable heart rate monitoring device on the market at present.It adopts the electrocardiogram signal method,whose principle is consistent with the hospital electrocardiogram,except that the hospital electrocardiogram is usually measured by 10 electrodes,so the data is more accurate.

The idea is that our heart beats are controlled by the nervous system, and this control signal is an electrical signal that gradually spreads to the surface of the body and can be measured on the surface of the skin using electrodes, which is equivalent to an electrical circuit formed between the body and the heart rate band. During the beating of the heart, small voltage changes are generated. Electrodes on either side of the band pick up these electrical changes and send them to a device (like a watch) to be further converted into the heart rate data we see.

3. Photoelectric volume method

At present, most wrist heart rate monitoring devices (such as sports watches and bracelets) on the market use photoelectric volume monitoring methods, such as the optical induction setting of BP smartwatch. The basic principle of this technology is to monitor heart rate by monitoring changes in blood volume through light reflection.


smart watch with heartbeat sensor


First, blood contains heme, and different hemes with different levels of oxygen absorb and reflect light to different degrees.

Second, under normal conditions, pulse fluctuations and heart rate are roughly the same. When the heart beats, capillaries, arteries and veins change continuously with the pulse volume, and the volume of light reflected by the blood also changes, while the reflection of the human skin, muscle, bone, fat, etc. to light is a fixed value.

According to these characteristics,BP watch illuminates the wrist with a green beam, and calculates the heartbeat rate through the change of light volume detected by the photoelectric diode.