The Development Of The Pulse Oximetry Based On Smart Phones

Monitoring of blood oxygen saturation value can prevent cardiovascular disease, etc. It is one of the standards of judging a person’s health. But the typical pulse oximetry does not have the function of storing daily monitoring parameters and mobile care, so there has certain limitation in practical applying. With the progress of mobile network, the performance of smartphones and data processing capacity is becoming more powerful, users are also becoming more. Then, family medical monitoring devices and smart phones are combined, which accomplishes home health care in mobile medical way. So, it has significance for developing the pluses oximetry based on smart phones.The project proposed a pulse oximetry system design scheme based on smart phone, this research work mainly includes:Firstly, the work introduced the measurement principle of oxygen saturation, the blood oxygen saturation measurement scheme was designed based on TI’s AFE4400 and TivaTM Cortex-M4 was as the processor. A preprocessing module circuit of oxygen saturation was realized based upon AFE4400. Hardware design and plate making was completed. Data software modules such as signal acquisition, data transmission and timely processing of a great deal of data were completed through efficient embedded software, showing the M4 excellent performance with low consumption.Secondly, blood oxygen saturation value could be calculated and obtained through analytical processing of the pulse wave, pulse wave signal carry a lot of human physiological and pathological information. In order to obtain more accurate pulse signal, the work studied wavelet transform, empirical mode decomposition(EMD) and ensemble empirical mode decomposition(EEMD) several filtering algorithms respectively. The work putted forward EMD and EEMD filtering algorithms which achieved band-pass filters according to the features of intrinsic mode function’s(IMF’s) time scale parameters. EMD and EEMD were more effective than wavelet transform in signal de-noising. The roles on the pulse wave signal processing of EMD and EEMD were compared through Hilbert-Huang spectrum. EEMD could both avoid modal aliasing problem and was more advantageous to the analysis of the pulse wave signal.Finally, the filtered data from M4 was transmitted to the smart phone through TI’s Bluetooth chip to calculate blood oxygen saturation and heart rate. The results of calculation and dynamic pulse wave form were displayed on the smart phone. At the same time, data could be real time storage. The smart phone APP about blood oxygen saturation has been realized.The major innovations of the paper are:(1) blood oxygen data acquisition module used TI’s integrated chip AFE4400 which was dedicated chip. AFE4400 chip has functions of pulse controlling, photoelectric detecting, signal amplification, signal filtering and sampling, these simplifies the peripheral circuit design. Combined with M4 the pretreatment circuit design was completed, it not only realized the function of blood oxygen signal acquisition and preprocessing, but also greatly reduced the volume of the whole detection circuit. The circuit had low power consumption, cost savings, high consistency characteristic and so on, so it provided convenience for industrialization.(2) The Android was as the development platform to design pulse oximetry APP, the APP coul complete the data analysis, calculation, storage and transmission and live display heart rate, blood oxygen saturation and the pulse wave form, so as to accomplish the remote medical treatment and improve the medical efficiency.