Interferometric Fibre-optic Hydrogen Sensor With Pt-loaded WO₃ Coating

Hydrogen as clean energy,which is widely used in military,aerospace,electrical industry and other fields.But it has the characteristics of wide explosive range and low explosive energy.Therefore,hydrogen leakage detection is crucially important.Optical fiber hydrogen sensors have been extensively concerned due to the advantages of immunity to electromagnetic interference,small volume and intrinsic safety.which is favored by users and researchers.Firstly,we test the hydrogen sensitive materials?Pt-WO₃?in aerobic environment with hydrogen,which will happen exothermic reaction.basing on the thermal effect,two kinds of interferometric fibre-optic hydrogen sensors have been proposed,their working principle and hydrogen response have been studied.And details are as follows:1.Testing the exothermic reaction characteristics of Pt-WO₃ with hydrogen.Coating Pt-WO₃ film on the surface of the negative temperature coefficient?NTC?thermistor,and then put it in the mixture of hydrogen and oxygen gas,by measuring the voltage of the thermistor to confirm exothermic reaction,and discuss the characteristics of hydrogen response,including sensitivity,response speed and so on.2.Basing on F-P interferometric fibre-optic hydrogen has been proposed and tested.It is fabricated by splicing a segment of capillary to a standard single mode fiber,the capillary with Pt-WO₃ coating is filled with polymer and the interface between polymer and single mode fiber,It forms a air micro-cavity.In order to eliminate the reflection,the end face of capillary is covered with toner.When hydrogen sensor with Pt-WO₃ coating is exposed to hydrogen,it will undergo an exothermic reaction and raises the temperature of sensor,causing the interference spectrum shift.The results show that the proposed sensor exhibits maximum hydrogen sensitivity of-17.48nm/%.The sensor is easy in fabrication,high hydrogen sensit ivity,low cost and fast response to hydrogen.3.Basing on polarization-maintaining interferometric reflection-type fibre-optic hydrogen has been proposed and tested.The sensor is made up of PANDA fiber with Pt-WO₃ coating.The experimental results show the sensor has a extremely high hydrogen sensitivity of-10.63nm/%.The main sensing idea is by monitor the interference spectrum shift of the interferometer caused by the temperature induced birefringence change.The sensor is fast response to hydrogen,compact size,easy in fabrication and high hydrogen sensitivity.In this paper,two types of hydrogen sensors have been demonstrated for hydrogen sensing.They have the advantages of compact size,easy in fabrication,high hydrogen sensitivity,fast response to hydrogen,good repeatability and stability,it is an ideal hydrogen sensor.