Introduction of SpO2 measure

author: Sky Wang
28/03/2022
Introduction of SpO2 measure



Anyone who knows the oximeter knows that the blood oxygen status in our body is monitored by the oximeter, which is used as the basic condition for judging our physical indicators. Therefore, many people now equip their family members or themselves with an oximeter so that they can perform self-testing anytime and anywhere when needed.

When it comes to the classification of oximeters, there are currently three main types on the market: finger clip oximeters, palm oximeters, and desktop oximeters. For home-based scene users, most people will choose the finger clip type, because it is exquisite and compact, easy to carry, accurate in measurement, and is not limited by time and place. It is convenient and fast.

Pulse oximeter types
In addition to the above-mentioned home use, there are also professional fitness professionals who use the oximeter more frequently, and professional medical places use it, and their demand for high-precision measurement of the oximeter is even more prominent. As for the technical development of the oximeter, the elimination of errors is one of the key elements of the precise measurement of the oximeter. The movement of the finger, the position where it is placed, the flow of blood, the movement of the body and the collection of light will all cause certain interference. weight. How to eliminate these errors is a test of the development engineer's consideration of photoelectric data conversion, coupled with algorithm optimization, to achieve the measurement accuracy of the oximeter and control the overall power consumption.

At present, the design principles of oximeter solution service providers on the market are the same: a blood oxygen saturation sensing circuit composed of red LED, infrared LED and photodiode, plus an LED drive circuit. After the red light and infrared light are transmitted through the finger, they are detected by the signal processing circuit, and then transmitted to the ADC module of the microcontroller to further calculate the percentage of blood oxygen saturation. Therefore, their test principles are roughly the same, and they all use photosensitive elements such as red light, infrared light LEDs and photodiodes to measure the transmission of fingertips and earlobes.

However, oximeter solution providers who have higher standards and requirements for the program have stricter and more demanding test requirements. In addition to the conventional test methods mentioned above, they also need to use their program products and professional oximeter simulation. The data is compared with the medical-grade oximeter, and the personnel breath-holding test is also added in the test link. Because there is no oxygen entering when a person is in a state of suffocation, but the oxygen in life is still continuously consumed. At this time, the blood oxygen saturation decreases, the oxygen concentration in the blood will decrease, and the value measured by the oximeter will be the same. Nature changes accordingly. And through this test, it can also be seen whether the data measured by the program is real data fed back by the human body, rather than "fake data".