We report on the employment of a biodegradable phosphate-based optical fiber as a pH sensing probe in physiological environment. The phosphate-based optical fiber preform was fabricated by the rod-in-tube technique. The fiber biodegradability was first tested in-vitro and then its biodegradability and toxicity were tested in-vivo. Optical probes for pH sensing were prepared by the immobilization of a fluorescent dye on the fiber tip by a sol-gel method. The fluorescence response of the pH-sensor was measured as a ratio of the emission intensities at the excitation wavelengths of 405 and 450 nm.
In this contribution we present a versatile sol-gel approach to highly transparent nanocrystalline thin films of
(Ho0,05Y0,95)2Ti2O7. We focused on their optical properties and relation between the processing parameters, their
structure, and resulting optical properties. Highly transparent and homogenous thin films have been prepared onto planar
silica substrates. Coated films were thermally treated to temperatures ranging from 700 to 900 °C. The effect of the
structure on the optical properties of prepared films were evaluated. The thickness of prepared layers ranged from 500 to
600 nm and the mean size of nanocrystals ranged around 25 nm in dependence on the processing conditions. Refractive
index of prepared films ranged from the value 1.8 up to 2.2. High optical transparency of prepared films along with the
ability to tailor the refractive index makes the films to be a suitable material for the construction of planar optical
Acidity of an environment expressed as pH is one of the key biological parameters. An optical sensing scheme together with the use of optical fiber probes can bring advantages to the pH monitoring such as fine spatial resolution, less interference with biological material or immunity to the electromagnetic field. An optical pH-sensor with fine spatial resolution suitable for measurement of pH in near-neutral range is presented and the influence of sensing probe preparation process onto the sensor performance is discussed in the paper. The sensor is based on an ion pair of 8- hydroxypyrrene-1,3,6-pyrene trisulfonic acid trisodium salt (HPTS) and hexadecyltrimethylammonium bromide (CTAB) immobilized by a sol-gel method on the tip of tapered-fiber probes. It was found that the sensor performance is affected significantly by the shape of the sensing layer.