Design Of Photoplethysmography Sensor Based On SD Card

The technique of Photoplethysmography has been applied in many different clinical settings. Due to the widespread of commercial home healthcare devices, PPG has become a proper detecting method for devices with compacted package, low power consumption,low cost and etc. In this paper, we combine Photoplethysmography and personal stereo to make it possible for daily monitoring. Violent body movement will influence the detection result because PPG device is vulnerable to motion artifacts. So, minimizing the motion artifacts will be an important task in the design of the device, which includes the building of the front-end sensor and the arithmetic processing of the raw signal.In this paper, we have developed an innovative PPG-based ear worn heart rate device which could be feasible to integrate with commercial earphone. According to the relevant literatures and some early tests,we rethink and redesign the sensor structure to minimize the external disturbance and strengthen the signal intensity, furthermore, a 3-axes accelerator is implemented as the motion reference for active noise cancellation notch filter that further remove the motion artifact especially the pace interferer. And the FAT16 file system on SD card is designed to be the storage solution, which make it possible to record continuously and easier for PC analysis.The experiment result has shown that the average accuracy in the case of running and walking have both reached 85% compared to the gold standard of industry.The dissertation includes six chapters:Chapter 1 elaborates the background and signification of the study of PPG.The current developments in correlative field are introduced in this dissertation, too.This chapter details the strengths and weaknesses of current methods, propose anew Design of Ear-wearable Photoplethysmography Sensor With 3-Axes Accelerator For Noise Cancellation.Chapter 2 describes the principle of the relative PPG technique, including the detection method of PPG sensor and the heart rate measurement. Chapter 3,4 focuses primarily on hardware design of electronic systems and software programs.Chapter 5 introduces the experimental data and test results.Chapter 6 isasummary and a prospect of the entire dissertation.