Extrinsic Fiber-Optic Sensor for Detection of Saliva pH

Abstract

Measurements of pH are important in industry, agriculture, medicine, etc. Two main principles, namely electrochemical and optical ones, have been employed in pH meters and sensors. This paper is aimed at the development of extrinsic fiber-optic sensors of saliva pH. Such sensors have already been used for monitoring pH changes caused by biological processes. In this paper, fiber-optic sensors consisted of inlet and outlet silica fibers transmitting light from a halogen lamp to a sample cell and then to a diode-array spectrometer. Two types of sample cells were used; namely a silica cell with a measurement path of 10 mm, and a special silica capillary cell with a hole diameter of 0.07 mm and measurement path up to 40 mm. This capillary, produced at the Institute, consists of a Bragg mirror applied onto the inner silica capillary wall. Both the sensors were calibrated by using Sorensen buffers with bromothymol blue and a commercial pH meter. The calibration curves were used for the determination of pH of saliva samples collected from one healthy person at different times. It has been found that the fiber-optic sensors provide us with lower pH values than the pH meter. This result can be explain by effects of saliva components on bromothymol blue spectra. By using a correlation line between pH values measured by the sensors and those from the pH meter the sensor reliability of about 0.3 pH units can be estimated.Keywords Fiber-optic sensor · Rectangular cell · Bragg capillary cell · Sorensen buffer · Bromothymol blue · Saliva pH Paper based on an Invited Lecture presented at MADICA

Microfluidic Platform for Examination of Effect of Chewing Xylitol Gum on Salivary pH, O2, and CO2

“…Previous microfluidic systems for the diagnosis of caries used various sensors to detect a wide range of biomarkers of saliva, plaque, specific metabolites, and bacterial products. It has already been emphasized that the examination of the pH of both salivary and dental plaque is an indispensable parameter in the diagnosis of the risk of caries [19,20]. Despite extensive efforts directed toward the identification of one or a combination of biomarkers with good predictive potential for the prevention, early diagnosis, and prognosis of dental caries as well as for monitoring the progression of the disease, all physical and biochemical biomarkers still need validation before chairside, point-of-care devices that can be widely used in everyday clinical practice [21].…”

The impact of ZnO configuration as an external layer on the sensitivity of a bi-layer coated polymer optical fiber probe

“…Predictable changes in the light transmission characteristics of the ber, because of alterations in the parameters being measured are the sensing principles of optical ber sensors. 1,2 Silica optical ber evanescent wave sensors are an example of large-scale analytical instruments that are used in devices for incorporating biological recognition elements 3,4 and monitoring parameters such as a wide range of gases, 5,6 pH, 7 temperature, 8 humidity, 9,10 ions 11 and refractive index. [12][13][14] This wide application range is due to its robustness, immunity to electromagnetic interference, high sensitivity, high selectivity, high integration, and potential portability for in situ and online measurements.…”

Simple Colorimetric and Fluorometric Assay Based on 2,3-Naphthalenedialdehyde for Melatonin in Human Saliva

“…Salivary fluid is composed of water (more than 95%), and of various electrolytes, hormones, enzymes, immunoglobulins, cytokines, etc. [49]. There are also glucose and nitrogenous products, such as urea and ammonia [50].…”