Non-contact optical fiber sensors using displacement and reflection methods for label-free formaldehyde detection

Abstract We have effectively developed a formaldehyde concentration sensor based on an optical fiber displacement sensor. Two distinct approaches based on displacement tuning and reflection spectrum measurement in combination with a UV light source were used to test our sensor. The UV–visible light source (OSL 2 Thorlabs) was used to illuminate the sample, and the power output of the backscattered radiation dropped linearly with the formaldehyde concentration. The sensor we tested showed remarkable sensitivity, linearity, and stability in measuring formaldehyde concentrations between 0% and 5%. The displacement tuning scheme achieved a sensitivity of 0.031 μ W/% with a linearity of 91%, whereas the reflection method exhibited a sensitivity of 2634.3 counts/% and a linearity of 98%. Furthermore, our sensor is non-contact, shielding the sample and probe from danger and damage. These findings show that our fiber bundle sensor has the potential to be a suitable instrument for tracking formaldehyde concentrations in the future for applications related to food safety.