Most optical hydrogen sensors are based on light intensity measurement and light intensity detection is vulnerable to the light source output and the optical fiber arrangement. To overcome the shortcomings, an optical fiber based sensor based on fiber Bragg grating (FBG) technique which is capable to measure the concentration of hydrogen dissolved is described in this paper. To examine the availability of monitoring initial hydrogen generation, a needle-to-plate partial discharge (PD) model was setup in the lab. The results between wavelength shifts of optical hydrogen sensor well agreed with conventional dissolved gas analysis (DGA), proving a potential utilization in the detection of dissolved hydrogen in power transformer.

A sensitive solid-state electrochemiluminesence (ECL) sensor for verapamil hydrochloride (VpCl) was fabricated based on the film formability of TiO 2 sol and electrocatalysis of ZnO@Ag. The immobilization of tris(2, 2′bipyridine) ruthenium (II) (Ru(bpy) 3 2+) by using TiO 2 sol/ZnO@Ag/silica sol composite exhibited stable ECL behaviors, and a sensitive and selective method was developed for VpCl determination. Under the optimal conditions, the ECL response of the sensor showed a linear correlation to the concentration of VpCl in the range of 1.0 × 10 −7 -1.0 × 10 −4 mol L −1 (R 2 = 0.9832) with a detection limit of 7.00 × 10 −9 mol L −1 (S/N = 3). The RSD of ECL response was 2.07 % for 1.0 × 10 −5 mol L −1 VpCl under 10 continuous cyclic scans. The spiked recovery was 97.90-104.50 % for determination of real VpCl sample. The proposed method exhibited selectivity and sensitivity for VpCl, and improved efficiency of Ru(bpy) 3 2+ .

This paper develops a multiple membranes fiber Bragg grating (FBG) hydrogen sensor and investigates the relationship between wavelength of FBG hydrogen sensor and ambient hydrogen concentration. A physical and mathematical model is built to explain the sensor behavior when it is subjected to the changes in hydrogen concentration and in temperature. The shifts in Bragg wavelengths of the Pd-coated FBG hydrogen sensor as a function of hydrogen partial pressure is obtained. Thus the developed FBG hydrogen sensor has a linear response to hydrogen in the low concentration range. Tests were carried on to prove the relationship between wavelength shift and hydrogen concentration.