Tapered optical fiber ammonia sensor coated with phenol red and tetraethyl ortho silicate (TEOS)

In this work we demonstrated a development of responsive optical fiber sensor for trace concentrations of ammonia(NH
₃
) gas. The sensing area was composed of phenol red and Tetraethyl ortho silicate (TEOS). A tapered fiber was chosen to enhance the sensitivity. Tapers were produced by chemical etching. The results was significantly evident that the tapered fiber sensor exhibited better interaction than un-tapered fiber sensor. We also found that the ratio between phenol red and TEOS (weight by volume) has influence on the sensitivity of sensor.