Spo2 sensor non-destructive oxygen saturation detection

Spo2 sensor non-destructive oxygen saturation detection

The blood oxygen sensor is an important component for detecting blood oxygen saturation, and its damage will directly lead to inaccurate detection or the whole machine will not work. The blood oxygen sensor can be mainly divided into a finger type, an earlobe type, a wrap type and an adhesive type according to the shape, and can be divided into an adult type, a child type, and an infant type according to the use. Regardless of the shape and type, the principle of the blood oxygen sensor is the same, and they are composed of a light-emitting device and a receiving device. Light emitting device

It consists of red light with a wavelength of 660 nm (650 nm) and an infrared light emitting tube with a wavelength of 940 nm (910 nm). Photosensitive receiving devices mostly use PIN-type photodiodes with large receiving area, high sensitivity, low dark current and low noise, which convert the received incident light signals into electrical signals.

Most of the newly developed pulse oximeters are finger-held sensor probes. The probe is placed on the fingertip when in use. Two LEDs placed side by side are fixed on the upper wall of the finger sleeve, and the emission wavelengths are 660 nm red light and 940 nm infrared light, respectively. The lower wall is a photosensitive receiving device that converts the red and infrared light transmitted through the finger into an electrical signal. When the oximeter is running, the time-sharing driving circuit allows the two LEDs to emit light at a certain time interval and at a lower duty ratio, respectively, according to the ratio of the luminous intensity of the photodiode to the transmitted light received by the photocell. Calculate the whole blood absorption rate a660 and a940, and then combine the experimentally calibrated coefficients A and B into the above formula, you can calculate the value of blood oxygen saturation.