PCBA solution design: a solution for household small oximeters

PCBA solution design: a solution for household small oximeters

Blood oxygen saturation refers to the capacity of oxygenated hemoglobin bound to oxygen molecules in the blood, as a percentage of the total bound hemoglobin capacity, which is the concentration of blood oxygen in the blood. In daily life, measuring blood pressure and blood sugar at home has become a habit for many people. After experiencing this epidemic, measuring blood oxygen has gradually become more important, and household finger clip oximeters have become a health monitoring tool for many households.

Introduction to the plan

The principle of a finger clip oximeter is that the red blood cells in the blood, including oxygenated hemoglobin (HbO2) and reduced hemoglobin (Hb), have different absorption abilities for red light (660nm) and infrared light (910nm). Reduced hemoglobin (Hb) absorbs more red light and less infrared radiation. On the contrary, oxyhemoglobin (HbO2) absorbs less red light and more infrared radiation. By setting red LED and infrared LED lights at the same position on the finger clip oximeter, when the light penetrates from one side of the finger to the other and is received by the photodiode, a corresponding proportional voltage can be generated. After processing by the microcontroller, the output result is displayed on the LCD screen.

The developed household small oximeter scheme adopts a 24 bit high-precision ADC SOC chip, combined with peripheral auxiliary execution circuits, and is designed through microcontroller program development. The household oximeter scheme can achieve the following functions:

Technical parameters of household small blood oxygen meter scheme

Display method: OLED display or LED display;

The display range of pulse oxygen saturation is 0% -100%;

The pulse rate display range is: 25bpm-250bpm.

Power requirements: 2 1.5V AAA batteries, internal power supply equipment;

Voltage adaptation range: DC 2.3V-3.0V, tolerance ± 5%;

Working current:<30mA.

Measurement accuracy: Blood oxygen saturation in the range of 70% -100% is ± 2%, less than 70% is undefined, pulse rate is 25bpm-250bpm, measurement error is ± 1% or ± 1bpm, whichever is larger.

Measurement performance under weak perfusion: It can correctly display blood oxygen saturation and pulse rate values when the pulse filling degree is 6%.