A pulse oximetry system with motion artifact reduction based on Fourier analysis

In this paper, a system that records photoplethysmography and performs motion artifact reduction is proposed. 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. In the calculation of SpO₂, the exact waveform is not the key point, whereas the amplitude plays the important role. Therefore, Fourier analysis is adopted to perform the noise cancellation. In the proposed system, data acquisition and analog filtering are done on a printed circuit board which is 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.