A Surface Hydrogen Sensor Based On Surface Plasmon Polaritons

Hydrogen gas is widely regarded as a potential energy source due to its cleanliness,chemical reactivity,recyclability,and natural abundance.However,hydrogen is highly flammable and becomes explosive when leaking into air.So,in order to reduce the risk,an effective hydrogen detection device is badly needed.Different mechanisms such as thermal,electrical,mechanical,acoustical,or optical reactions have been employed in hydrogen detection before.Compared to other methods,optic-based sensing devices are supposed to be quite sensitive,relatively compact,cost-effective,reliable,and immune to electromagnetic interference.As the size of the device develop into sub-wavelength.To overcome the diffraction limit,the surface plasmon polariton(SPP)technology is employed.SPP is a special mode of electromagnetic wave,and by utilizing that,overcoming the limit of diffraction becomes possible.Thus,SPP has been implemented in different nanoscale structure researches.And by utilizing that,the sensor structure could be smaller and have better performance.In this study,we present a novel hydrogen sensor based on a nanoscale SPP resonator.The structure mainly consists of a palladium(Pd)-silver(Ag)bimetal layer and a metal-insulator-metal(MIM)structure.When the concentration of hydrogen gas increases,the deformation of the bimetal layer will incur a wavelength shift in the resonator.By utilizing the bimetal layer,the hydrogen gas can contact with Pd layer directly,thus,decreasing the response time needed.In addition,detaching the bimetal layer structure and the resonator provides more room for future improvement.In this thesis,mathematical modeling and computer simulation are used to analyze the structure.Later on,ways of optimizing the sensor structure are discussed.Finally,we found that the structure presents a good performance.Compared to sensors also based on SPP,our structure maintains a response time of 149.9s.However,the sensitivity comes to 6.44nm/(v/v-%hydrogen),which is 23 times higher than a typical sensor also based on SPP.In addition,the structure still has room for optimizing.