Processing of Photoplethysmography (PPG) Signal Using Virtual Instrumentation

International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue V, May 2018 | ISSN 2321–2705

Processing of Photoplethysmography (PPG) Signal Using Virtual Instrumentation

Arvind Raut¹, M.S.Panse²

¹Student M. Tech Electronics, ²Professor
Department of Electrical Engineering, VJTI, Mumbai, Maharashtra, India

Abstract – Photoplethysmography (PPG) sensor is an optical sensor and is used to measure the blood volumetric changes occurring in the various parts of the body. They can be well utilized to extract information related to cardiovascular system. In this study the PPG signal is acquired at rate of 125Hz through Arduino and processed to determine the characteristic point such as peaks. In PPG signals analysis, the accuracy is affected by Motion Artifacts and noise. To remove these noises Wavelet transform is used and the performance is evaluated based on comparative results of cross correlation.

Index Terms— Photoplethysmography, cardiovascular system, Wavelet transform, Arduino, Motion artefact.

I. INTRODUCTION

The Instruments used for measuring blood volume changes are called Plethysmographs and the technique is called Plethysmography. It is a non-invasive and widely adapted in a variety of wearable systems due to its ease of implementation. There is much information contained within PPG waveform, which may be interpreted with appropriate signal analysis [1] PPG signal comprise two components, first is pulsatile (AC) component and second non pulsatile (DC) component. Due to change in pulsatile blood volume it results in AC component. The DC component resulted due to background absorption which is the component without a pulsatile signal.
There are two PPG operational configurations one is transmission mode where the tissue sample e.g. Fingertip is placed between the source and photo detector, and in reflection mode where the LED and photo detector are placed side-by-side to tissue sample [2] The photoplethysmographic sensors are that to be attached to afinger, can be integrated into the ear-phones[3],can be implemented in a forehead band or used as a wristsensor[4].The noise may introduced at analog front end due to probe tissue movement i.e. by subject’s movements, ambient light interference but it can be reduced using Velcro wrap around cuff. Also the power line noise gets added in signal, to remove these noises especially the motion artifact various approaches were proposed. Among them Fast Fourier transform (FFT) analysis signals have been shown to reduce the impact of motion artifact. However, FFT analysis has shown to perform poorly for quasi-periodic data sets [5].Different approach based on Adaptive Filters, for motion artifact reduction in PPG signals. But, in order to use adaptive filter technique, a reference signal is needed and it requires an additional hardware setup [6]-[8].

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