[scheme design] scheme of household oximeter based on single chip microcomputer

　　 The oximeter is used to measure pulse rate 、 Instruments and equipment for blood oxygen concentration and perfusion index , Blood oxygen concentration is one of the important basic data in clinical medicine . If there are conditions , People should always monitor their oxygen saturation , It is more beneficial to your health . A scheme of household oximeter based on single chip microcomputer is introduced , The following is a detailed knowledge description .
　　
　　 One 、 Measuring principle of oximeter
　　
　　 The oximeter is based on the reduction of hemoglobin （Hb）、 Oxygenated hemoglobin （HbO2） The absorption spectrum characteristics in the red and near-infrared regions are the theoretical basis , Application LambertBeer Law establishes empirical formulas for data processing . The instrument adopts photoelectric blood oxygen detection technology combined with volume pulse tracing technology , Two beams of light with different wavelengths irradiate the fingertip of the human body through the perspective clip finger sensor, and the measurement signal is obtained by the photosensitive element , The obtained information is processed by the electronic circuit and microprocessor, and the measured results are displayed on the display screen .
　　
　　 Two 、 Technical characteristics of the oximeter
　　
　　1、 Main performance of the oximeter
　　
　　A. The blood oxygen saturation value is displayed
　　
　　B. Pulse rate value 、 Bar graph display
　　
　　C. Pulse waveform display
　　
　　D. Battery level indication
　　
　　E. Automatic shutdown function ： After the tested finger is detached 8s Internal automatic shutdown
　　
　　F. You can change the display direction , Depending on the display mode
　　
　　2、 Main parameters of the oximeter
　　
　　A. Blood oxygen saturation measurement range ：35%～100％ error ： When the measurement range of blood oxygen saturation is 70%～100％, The allowable absolute error is ±2％; Less than 70% No definition .
　　
　　B. Pulse rate measurement range ：30bpm（ Time /min）～250bpm( Time /min) error ：±2bpm or ±2% Take a big value .
　　
　　C. Display resolution ： Blood oxygen saturation is 1%, Pulse rate is 1bpm.
　　
　　D. The error of weak perfusion is 0.3% when , The oximeter can correctly display oxygen saturation and pulse rate , The error of blood oxygen saturation is ±3%; Pulse rate error is ±2bpm or ±2% Take a big value .（ remarks ： This indicator only refers to high-end oximeters , Weak perfusion degree of low-end oximeter >=1）
　　
　　E. The anti ambient light interference ability compares the blood oxygen measurement value under indoor natural light and existing lighting sources with the measurement value under dark room conditions , The deviation is less than ±1%.
　　
　　F. Working voltage ：2.6VDC～3.0VDC It shall work normally .
　　
　　G. Power waste ：<30mA
　　
　　3、 Features of oximeter products
　　
　　 Easy to use .
　　
　　 High precision , Low power consumption .
　　
　　 Small volume , Light weight , be easy to carry about .