What is blood oxygen saturation?
The blood in the human body can transport oxygen from the lungs to all parts of the body. Blood is mainly composed of water. The easiest way to carry oxygen in a liquid is to dissolve the oxygen in the liquid, just like dissolving sugar or salt in water. However, because we humans are very active creatures with high metabolic demands, the blood cannot dissolve enough oxygen to meet our needs. Therefore, our body has created a way to increase the blood's ability to carry oxygen. This ingenious method requires the use of a special molecule called hemoglobin. Each hemoglobin molecule is composed of four individual heme units, and each heme unit requires an iron atom. A complete hemoglobin molecule can carry four oxygen molecules-each heme group carries one oxygen molecule. The iron in the hemoglobin molecule produces a red color, just like the iron in soil or rock makes it appear red. The hemoglobin in the blood does not float freely in the blood, but is packed in cells. The red color of hemoglobin makes these cells appear red, so these cells are called red blood cells. Red blood cells are suspended in the water matrix of the blood (also called plasma). There are many other types of cells, proteins, and electrolytes dissolved in the plasma. If all the red blood cells are removed, the remaining plasma will no longer appear red, but will only be a transparent to pale yellow liquid.
How does hemoglobin bind to oxygen atoms?
Each hemoglobin molecule can carry four oxygen atoms. The oxygen atom binds to the iron atom in the heme group. When the oxygen atom combines with the iron atom in the heme group, it changes the color of the iron atom from dark red to bright red. This is why oxygenated blood appears bright red. Hypoxic blood appears dark red. When this dark red blood is observed through the skin (skin is like a pink filter), it appears light blue. This is why we can sometimes see our veins appear light blue through the skin. This is also the reason why hypoxic blood is described as blue and oxygenated blood is described as red in textbooks.
So how does the wearable smart watch perform blood oxygen monitoring?
Wearable smart watches monitor blood oxygen saturation mainly through optical sensors. The optical sensor irradiates the skin with red light and infrared light, and then obtains the red light and infrared light reflected by the blood vessels under the skin, and finally calculates the blood oxygen through an algorithm. The optical sensor is the core of blood oxygen measurement, and the accuracy of the optical sensor is very important to the accuracy of the measurement result.
At present, major companies in the industry are taking various measures to improve accuracy. The main way is to improve the accuracy and number of sensors.
VeePoo Watch RIG has built-in high-precision photoelectric sensors, 7 groups of light path designs, 6 LED light sources, 3 electrodes and advanced blood oxygen monitoring algorithms, using green, red, infrared, and infrared LEDs to calculate blood oxygen content. It also uses intuitive data to let the wearer know the status of the body's absorption of oxygen and the amount of oxygen delivered to the body. At the same time, VeePoo Watch RIG not only has a blood oxygen monitoring function, but also other monitoring functions, such as blood pressure, heart rate, scientific sleep, etc., effectively helping the wearer to have a more comprehensive understanding of their overall health. In addition, Apple watch, HUAWEI watch, Xiaomi, Huami, etc. are also among the leaders.
It is foreseeable that with the application of blood oxygen monitoring functions to wearable smart watches, more medical monitoring technologies will be applied to smart watches in the future. Currently, the industry is studying how to improve the accuracy of blood glucose monitoring and apply it to smart watches. VeePoo health&tech's blood glucose monitoring has reached 70%, and it will be applied to the device soon.