High-Sensitivity Biosensor With Optical Tunneling Effect Excited by Long-Range Surface Plasmon Resonance

Optical tunneling is an effect extremely sensitive to wavelength changes. In this article, we use this effect to design a new type of biosensor. The tunneling effect is excited by long range surface plasmon resonance, the energy is concentrated in the sensing medium in the form of standing waves, which lead a very high wavelength sensitivity and quality factor. By using COMSOL for finite element analysis, for the sensor structure of BK7/Cytop /Al
₂
O
₃
/Ag/Al
₂
O
₃
/sensing media/air, a quality factor of 10296 RIU
^-1
is achieved under angle modulation, a sensitivity of 170,000 nm/ RIU and a quality factor of 11333 RIU
^-1
are obtained under wavelength modulation. At the same time, the advantage of this structure is that there is no excessive requirement on the refractive index of the material, and a good sensing effect can be achieved even if the material is cheap and easy to prepare. After optimization, this structure is suitable for sensing media with a refractive index of 1.335-1.375, which can be applied to most liquid solutions.