Abstract
Nowadays, mobile health care has been greatly emphasized. Biomedical signal acquisition techniques developed rapidly over this decade. Blood oxygen saturation (SpO2) is the percentage of oxygenated hemoglobin among total hemoglobin. It reflects the situation of cardio-pulmonary function and is widely used is hospitals. In this study, a system that records photoplethysmography (PPG) and performs motion artifact reduction is introduced. In order to calculate SpO2, accurate amplitude of PPG is essential. As a matter of fact that the PPG signal is acquired through an optical sensor, it is prone to be affected by motion artifact. As a result, noise cancellation is a major issue in the calculation of SpO2. When computing SpO2, the exact waveform is not the key point, whereas the amplitude plays the important role. Therefore, Fourier analysis with ECG signal is adopted to perform the noise cancellation. In the proposed system, data acquisition and analog filtering is done on a printed circuit board (PCB) controlled by an FPGA. The acquired data are sent to a computer, where Fourier analysis is done to cancel motion artifact. Experiments have been done to demonstrate the performance of the proposed algorithm. The proposed system performs PPG signal acquisition, motion artifact reduction and SpO2 calculation.