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An optical spectroscopic based reflective sensor for CO2 measurement with signal to noise ratio improvement

M. R. SALIM1,* , M. YAACOB2, M. H. IBRAHIM1, A. I. AZMI1, N. H. NGAJIKIN1, G. DOOLY3, E. LEWIS3

Affiliation

  1. Universiti Teknologi Malaysia, Faculty of Electrical Engineering, 81310 Skudai, Johor, Malaysia.
  2. Department of Communication Engineering, UniversitiTun Hussein Onn Malaysia, Batu Pahat, Johor, Malaysia
  3. University of Limerick, Department of Electronic and Computer Engineering, Plassey Road., Limerick, Ireland

Abstract

This paper presents recent work in measuring carbon dioxide (CO2) using an absorption spectroscopy method within the mid-IR region. A multi-path optical fibre based reflective sensor is proven to be capable of detecting CO2 at lower level (<15%) and higher level of concentration (>15%). For low level detection, the sensor is capable of measuring CO2 concentration from 0.8% to 14.8%, while for high level of detection, the sensor showed its capability to detect CO2 concentration from 15.1% to 44.6% with high accuracy. By eliminating unwanted noises using suitable filtering technique, the voltage response from the system has become more stable and without significant loss in voltage, thus improving the signal-to-noise ratio and stability of the system. The average signal-to-noise ratio for each of the filter types, no filter, lowpass, bandpass were calculated as being 53.4, 69.1 and 119.0 respectively. Similarly, moving average technique was developed in LabVIEW to improve voltage response with less noise and interference, resulting better overall system’s performance..

Keywords

Absorption spectroscopy, Mid-infrared, carbon dioxide, filtering, moving average technique.

Submitted at: March 30, 2015
Accepted at: May 7, 2015

Citation

M. R. SALIM, M. YAACOB, M. H. IBRAHIM, A. I. AZMI, N. H. NGAJIKIN, G. DOOLY, E. LEWIS, An optical spectroscopic based reflective sensor for CO2 measurement with signal to noise ratio improvement, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 5-6, pp. 519-525 (2015)