Optical fibre sensor for simultaneous temperature and relative humidity measurement: Towards absolute humidity evaluation

Temperature and humidity are essential parameters in monitoring the health of patients critical care. An optical fibre sensor has been developed for simultaneous measurement relative (RH) temperature at a single tip based on reflected intensity. Combining these measurements enables absolute values to be obtained. The is first modified with coating poly(allylamine hydrochloride) (PAH) / silica nanoparticles (SiO2 NPs) then coated thermochromic liquid crystal (TLC) measurement. Experimental results demonstrate that RH sensitivity respectively 0.43 %/RH% (intensity wavelength 650 nm) from 55 90% (R2 = 0.973) 3.97 nm/°C 28 46 °C (R2>0.99). Moreover, proposed low crosstalk between each sensing parameters, response time 3.1 s (30–38 °C) 13.2 (20–80 %). In comparison grating sensors low-cost simple manufacturing process which potential find widespread use healthcare applications.