Research On Pulse And Oxygen Saturation Monitoring System Based On FPGA

Pulse is animportantindex for human’s life. Oxygen is the fundamental material that maintainspeople’s normal vital activities. The oxygen saturation is an important parameter that shows thesituation of oxygen supply for human’s tissue. With the improvement of life, people begin to paymore attention to their health. Traditional health care centers on professional medical institutions.To acquire irregular health care, professional medical equipment must be adopted. At present, themonitoring of pulse and oxygen saturation is mainly based on the optical method with the type oftransmission. While it is restricted by the measuring site. So the optical method with the type ofreflection, which aims at the measurement of pulse and oxygen saturation for human’s body,becomes the main direction on research. And it is widely used in clinic. For instance the monitoringof cerebral oxygen saturation and fetal oxygen saturation during labor. Besides, it earns wideprospect for future application in the area of intelligent home. At that time, people can enjoy healthcare that is in real time, daily and smart.The research on the pulse and oxygen saturation monitoring system is based on FPGA. Thesystem consists of signal acquisition, interface of data and signal processing, short-distance wirelessdata communication and user interface (UI), a total of four sub systems. The reflex blood oxygensensor module is applied to collect the signal acts to the light in the signal acquisition sub system.And the emission component emits light at two wavelengths. After the reflection of human’s tissue,the light is received and then transformed into current by the reception component. Then, with theprocessing of amplification, filtering and A/D transformation by the analog front end, data is outputtowards the interface of data and signal processing sub system, which is based on the platform ofFPGA. It implements the SPI interface with the analog front end, the I2C data transmitting interfacewith the short-distance wireless data communication sub system and the Two-Channel Time Division Radix-2DIF algorithm, which is an improved algorithm based on the FFT in theapplication environment of this paper. The SPI interface implements the configuration for theregisters inside the analog front end, which makes the analog front end work in the environmentthat is defined by the user. In addition, it realizes the transmission of the output data from the analogfront end, which is then processed by the algorithm. The short-distance wireless data communicationsub system is based on the platform of the Bluetooth Low Energy (BLE) SoC (System on Chip).The point to point transmitting method is adopted. The application of BLE is developed in the Keildevelopment environment based on the protocol stack of S110SoftDevice. The user interface (UI)sub system makes use of the devices like smart phone that support the technology of Bluetooth4.0as the user terminal. The Android application is designed to receive the data sent out from the BLESoC based on the Android operation system. Then the information of pulse and oxygen saturationis displayed on the interface of the terminal application in real time. What’s more, the applicationgives out alarm when there is abnormity, which makes it easy and practical to use.To test and verify the functions of each sub system, they are designed in the way that each ofthem is divided into models according the functions. The results show that every functional modelachieves the desired goals. At last, all the sub systems are joined up to test and verify the overallfunction of the system. The parameters of pulse and oxygen saturation are observed and obtainedvia the user terminals like smart phone. And the function of alarm for exceptional situation is tested.The test results are compared with the normal reference values. It shows that the system achievesthe basic functions and the expected goals are achieved.