The main measurement indexes of sphygmomanometer chip are pulse rate, oxygen saturation and perfusion index (PI). Blood pressure saturation (SpO2) is one of the important fundamental data in clinical medicine. Blood pressure saturation refers to the percentage of separated O2 volume in total separable O2 volume.

The sphygmomanometer, literally, refers to the instrument for measuring blood pressure. Anoxic patients should use the sphygmomanometer for a long time to detect the blood pressure content, which can effectively prevent the risk of attack. If there is a lack of oxygen, the time to supplement oxygen will greatly reduce the opportunity of disease attack.

The first blood pressure monitor was developed by Millikan in the 1940s. It monitors the ratio of oxygen carrying hemoglobin to non oxygen carrying hemoglobin in the arteries. A typical blood oxygen saturation meter comes with two light emitting diodes. These two light-emitting diodes face the patient's test area - usually the fingertip or earlobe. One diode emits a beam of light with a wavelength of 660 nanometers, while the other emits 905910 or 940 nanometers. The absorption rates of oxygen-containing hemoglobin at these two wavelengths differ greatly from those without oxygen. By applying this property, the ratio of two types of hemoglobin can be calculated. The testing process usually does not require blood to be drawn from the patient. A typical blood pressure monitor can also show a patient's pulse.

The main components of the sphygmomanometer chip are:

1. A microprocessor, memory (EPROM and RAM), two digital to analog converters that control LEDs, devices that stop filtering and amplifying signals received by photodiodes, and analog-to-digital converters that digitize the received signals to provide the corresponding microprocessor. LEDs and photodiodes are placed in small probes that come into contact with the patient's fingertips or earlobes. The pulse oximeter generally also includes a small LCD display;

2. Appearance: Similar to a needle tube, with a moderate appearance. Using bento is a necessity for the demand group.

A typical blood pressure monitor can also show a patient's pulse. According to Beer Lambert's law, the functional relationship between the ratio R/IR and arterial oxygen saturation (SaO2) should be linear. However, since biological tissue is a complex optical system with strong scattering, weak absorption and anisotropy [2~4], which does not fully conform to the classical Beer Lambert's law, it leads to the measurement of relative changes in red light and infrared absorbance (R/IR value), It is difficult to establish a mathematical model of the relationship with arterial blood pressure saturation (SaO2). The correspondence between R/IR and SaO2 can only be confirmed through experimental methods, namely the calibration curve. Most pulse and blood pressure meter manufacturers use experimental methods to obtain calibration curves to complete the pre factory calibration of their products.