Temperature compensation of fluorescence intensity-based fiber-optic oxygen sensors using modified Stern–Volmer model

In practical sensing applications, temperature effects are of particular concern, and hence it is necessary to develop the means to correct the fluorescence intensity measurement in accordance with the working temperature. Accordingly, this study develops a modified Stern–Volmer model to compensate for the temperature drift of oxygen concentration measurements obtained using fiber-optic sensors. The oxygen sensors considered in this study are based on teraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS) or n-propyltrimethoxysilane (n-propyl-TriMOS)/3,3,3-trifluoropropyltrimethoxysilane (TFP-TriMOS) composite xerogels doped with platinum meso-tetrakis(pentafluorophenyl)porphine (PtTFPP).

The experimental results are fitted to the modified Stern–Volmer model in order to compute suitable values for a temperature compensation coefficient at different working temperatures. It is found that the proposed temperature compensation method reduces the difference in the oxygen concentration measurement for working temperatures in the range of 25–70 °C as compared to data without compensation. The linearity and sensitivity of PtTFPP-doped n-propyl-TriMOS/TFP-TriMOS sensor are better than PtTFPP-doped TEOS/Octyl-triEOS sensor for working temperatures in the range of 25–70 °C.

The proposed approach could provide a straightforward and effective means of improving the accuracy of fiber-optic oxygen sensors if a variable attenuator is designed according to the temperature compensation coefficient. Thus, the fiber-optic oxygen sensor with a variable attenuator could work in a broad temperature range without using a temperature sensor.     

A Plastic Optical Fiber Sensor for the Dual Sensing of Temperature and Oxygen

This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using an ultraviolet light-emitting diode light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no crosstalk effects. Our studies show that the temperature response of the sensor is independent of the oxygen concentration. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the noncontact, simultaneous sensing of temperature and oxygen in general biological and medical applications.