Label-free optofluidic sensor based on polymeric microresonator for the detection of cadmium ions in tap water

Abstract In this article, we report on the specific detection of cadmium ions in water using an optofluidic sensor based on a polymeric microresonator functionalized with a cadmium ion specific ligand. A limit of detection down to (0.31 ± 0.07) nM ((33.9 ± 7.8) ng/L) in deionized water and (0.36 ± 0.10) nM ((38.9 ± 10.6) ng/L) in tap water was achieved. When applying a post-measurement digital treatment onto measured signals using a median filter, the sensor limit of detection was reduced to (0.13 ± 0.03) nM ((14.8 ± 0.07) ng/L) in deionized water and to (0.17 ± 0.04) nM ((18.3 ± 4.4) ng/L) in tap water. The chemical sensor could be adapted to build a portable instrument for in situ analysis.