A novel hydrogen sensor based on Pd/Ni co-sputtered coating on micro fiber Bragg grating (MFBG) is proposed and experimentally demonstrated. The microfiber is stretched uniformly and the Bragg grating is directly inscribed on the microfiber without hydrogen loading using 193 nm ArF excimer laser and a phase mask. Palladium and nickel coatings are co-sputtered on the micro fiber Bragg grating for hydrogen sensing. The MFBG hydrogen sensors are characterized concerning their response to the hydrogen, ambient temperature and ambient refractive index, respectively. The performance of the proposed MFBG hydrogen sensor is obviously enhanced, especially when compared to standard FBG hydrogen sensors.
This paper reviews the recent development of optical fiber sensors at the National Engineering Laboratory for Optic Fiber Sensing Technologies (NEL-FOST) at Wuhan University of Technology. Integration of optical fiber with sensitive thin films will new possibilities for industry application, such as optical fiber hydrogen sensors based on Pt-doped WO<sub>3</sub> coatings, fiber humidity sensors with porous oxide coating and high-temperature sapphire fiber sensors based on multilayer coating on fiber tip. Ultra-weak FBG array with thousand of FBGs with on-line draw tower technology will enable FBG sensing network with large capacity, also improved sensing performance and mechanical stability.
In this paper, a new complex sensing film containing both optical indicator and enzyme was prepared and its sensing
properties were studied, using cellulose acetate (CA) as the carrier and tris (2,2'-blpyridyl) dichloro-ruthenium (II)
hexahydrate (Ru(bpy)<sub>3</sub>Cl<sub>2</sub>) as the indicator. The cross-linking method was used to immobilize glucose oxidase (GOD).
The immobilization conditions were optimized: the concentration of sodium periodate as 0.2 M and the reaction time as
30 min, those for ethanediamine as 0.03 M and 2.5 hours, those for GA as 1.5% (v/v) and 2 hours, those for GOD as 35
mg/ml and 21h. The optimal temperature and pH value for the catalytic properties of the sensing film are 38 °C and 7.0,
respectively. A fiber optic glucose sensor with this complex sensing film has been studied. The results show that its
detecting range is 100-600 mg/dl and its response time is less than 20 seconds.
In this paper, Glucose oxidase (GOD) was immobilized on a novel silica membrane. The multifunctional sensing
membrane was prepared by sol-gel method. GOD was immobilized on the aminated silica surfaces by glutaraldehyde
cross-linking method. The fiber optical glucose sensor based on fluorescence quenching was designed and fabricated
using lock-in amplifying technology to realize the detection of glucose concentration. The experimental results show that
a linear range between phase delay φ and the glucose concentration of the solution was observed in the concentration
range of 100 to 600 mg/dl and the detection limit is 50mg/dl, the sensor can meet the demand of clinical application. The
response time of the sensing membrane was about 15s. The experimental results demonstrated that this biosensor with
the multifunctional sensing membranes has high sensitivity, repeatability, good stability and fast response.