Research On Micro-mirror Optical Fiber Hydrogen Sensor

Hydrogen fuel is a new fuel which is non-polluting. But the character of hydrogen is highly detonable and flammable, which makes hydrogen fuel storage, use and transportation may pose a risk. Therefore, it becomes extremely important to early warn of hydrogen leaking which can protect human life and property security.Taking the flammability of hydrogen into account, in this paper, optical fiber is used as a sensing probe in hydrogen environment to test the hydrogen concentration which is below the explosive limit. Studying on micro-mirror optic fiber hydrogen sensor, by the principle of light reflection and transmission on the metal surface combined with the reaction mechanism of hydrogen-sensitive film and hydrogen, it coats hydrogen sensitive film on fiber end face. Through the relationship between the hydrogen concentration and hydrogen-sensitive film refractive index, it can research the optic fiber hydrogen sensor test system based on the principle of light reflection and transmission on the metal surface.By means of optical grinding and cutting optical fiber end face, it can access clean fiber end face. Using high vacuum magnetron sputtering system, it is coated sensitive film on the optical fiber end face, silicon, glass. Using electron microscope(SEM) to scan the surface appearance of sensitive films and using UV-Vis photometer of different wavelengths to test the transmittance of sensitive films on the glass, to test the micro and macro performance of sensitive film. It can study the properties of Pd, WO3 and Pd/WO3 hydrogen sensing film on single-mode fiber end face. C8051F120 MCU chip board transfers data to computer terminals through serial port, records and saves the test data.Through a series of tests, Pd and WO3 co-sputtered film can completely change cracks and shedding of Pd film. This film can enhance the mechanical strength of the sensitive film. By testing the intensity range and response time on different thickness and different hydrogen-sensitive film, Pd and WO3 co-sputtered film can distinguish the standard hydrogen concentration of 0.01%. But response is the most obvious in concentration of 2%-4%. There are also responses at concentration of 0.01%-2% and more than 4%. By improving the thickness of film, the response time can be lower than 15s and the recovery time can be lower than 200s. The Pd and WO3 co-sputtered film has good reproducibility. In addition, by using C8051F120 microcontroller chip board, it improves the data transmission capabilities of the light intensity-type hydrogen sensors which were manually recorded data, so the data is more accuracy and continuity.