Refractometric fiber optic mode-filtered light chemical sensor for acetic acid

A refractometric fiber-optic chemical sensor bas don mode- filtered light detection (MFLD) was designed. This sensor was fabricated by inserting a non-chem- or bio-modified fiber core into a silica capillary with a CCD detector as the multichannel-signal capture. An interesting observation was obtained that there is an increase in signal with a decrease in sample refractive index in this unclad fiber sensor, just contrary to the polymer-clad fiber instead sensor reported previously. Academic deduction of the light propagation in detail, which was demonstrated by our experimental results, further interprets the reason of the difference between the unclad sensor and the polymer-clad sensor, and provides theoretical foundation on development of a MFLD-derived analyzer with synchronization of separation and assay in future work. This sensor was also demonstrated to successfully apply to detection of acetic acid with linear response of 0-90 percent and relative coefficient of 0.9972. The sensor's advantages in high S/N ratio and instant response show its potentials in food and chemical industries as a general sensor.