Currently, the most well-known heart rate monitoring products on the market are still smart bracelets/watches. So, what is the principle of smart bracelet/watch heart rate monitoring？
Currently, there are three principles for heart rate monitoring:
1. Photoelectric transmission monitor method
In principle, the sensor that contacts the bracelet with the skin emits a beam of light hitting the skin to measure the reflected/transmitted light. “Because blood has an absorption effect on light at a specific wavelength, each time the heart pumps blood, that wavelength is greatly absorbed, which can determine the heartbeat.”. This method consumes a lot of power and is also subject to ambient light interference.
2. ECG signal monitor method
The sensor of the bracelet can measure the electrical signal of myocardial contraction to determine the user’s heart rate, and the principle is similar to that of an electrocardiogram. In each cardiac cycle, the atria and ventricles of the human heart are successively excited, accompanied by the continuous operation of countless myocardial cells, which can cause potential changes. By detecting periodic changes in electrocardiogram, the heart rate can be detected. Due to the complexity of the circuit, the large footprint of the PCB, and the susceptibility to electromagnetic interference, it is difficult to use this method for bracelets.
3. Electric pulse monitor method
“Because every heartbeat causes vibrations in the body, high-precision sensors can capture this vibration, and then signal processing can be performed to obtain a heartbeat.”.
Electric pulse measurement uses dry electrode technology to obtain human ECG data, and obtains heart rate through peak detection. The principle is similar to ECG. Before the mechanical contraction of the heart, an electrical excitation is generated, which can be transmitted to the body surface through human tissue. The electrical pulse monitor method measures the heart rate by monitoring this electrical excitation. Generally, products such as intelligent seat cushions or massagers will adopt this method.
The accuracy of data depends on sensors and algorithms.
Due to unprofessional monitoring equipment, bracelets/watches cannot directly monitor pulse conditions, and external environment interference is too large, which requires algorithms to eliminate interference items. At the same time, the sensor should also be accurate and sensitive, capable of receiving photoelectric signals without dead corners, thereby ensuring the accuracy of data.
For heart rate monitoring, Plus1Health has advanced algorithms, accurate and highly sensitive sensors that can provide heart rate detection module solutions.
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