Formaldehyde sensing using micro-loop resonator

Abstract

Formaldehyde (CH2O) liquid sensor has been successfully fabricated using micro-loop resonator (MLR) based on whispering gallery mode (WGM) concept. An excellent sensing response towards formaldehyde liquid concentrations level ranging from 0% to 5% was observed. It is because of the changeable effective index and surface absorption phenomenon which lead to different light characteristic inside the MLR. The output power reduced linearly from-18.9 dBm to-36.2.dBm as the concentration increases. The sensitivity obtained was 3.6561 dBm/% with linearity of 99.1% and resolution of 0.0207%. The proposed sensor has simplicity, easy fabrication, better resolution and low cost. This application is essential in monitoring toxic gases and human health.