An experimental study about the utilization of Liquicoat® solutions for the fabrication of pH optical fiber sensors

Response time enhancement of pH sensing films by means of hydrophilic nanostructured coatings

“…Suitable fluorescence indicators that are sensitive to pH and exhibit changes in fluorescence intensity have been used as molecular recognition materials in common optical sensors. For the immobilization of these fluorescent indicators several techniques have been proposed (sol-gel, cellulosic films, Langmuir-Blodgett films) [6][7][8][9][10][11][12][13][14] but most of them suffer from poor repeatability and complex chemistry, being often limited to a single layer without thickness control of the structures at nanometer scale.…”

Volatile alcoholic compounds fibre optic nanosensor

“…In last few years, it has been presented as a very useful technique to build up two-beams Fabry-Perot (also called Fizeau) nanocavities on optical fibre with lengths less than a micrometer [15]. Simplicity or reproducibility are the main advantages this method offers respect to other deposition techniques employed to develop optical fibre sensors such as for example sol-gel [16,17], dip coating [18] or Langmuir-Blodgett [19].…”

Fluorescence based fibre optic pH sensor for the pH 10–13 range suitable for corrosion monitoring in concrete structures

“…Prior work has shown that poor immobilization results in dye leaching and consequently a drifting of the calibration of the probe, which leads to the gradual breakdown of its useful sensing ability [17]. Among several widely used immobilization methods are included absorption or entrapment [45][46][47], layer-by-layer (LbL) electrostatic self-assembly [48,49] and covalent binding [18,[50][51][52][53]. The first two approaches are generally easier and simpler but not suitable for this type of application as they suffer from numerous disadvantages such as cracking, dye leaching and inhomogeneity of the material (in case of absorption or entrapment in a sol-gel matrix) or irreversible damage at extreme pH values and issue related to effect of ionic strength (in case of electrostatic attachment).…”