Optical Sensor Applications Based On Nanomaterials Stacking

Nanomaterials have attracted wide attention due to their characteristics such as surface effect,high catalytic rate,high electrical conductivity and quantum size effect.Compared with traditional bulk materials,nanomaterials have excellent optical,electrical,thermal,acoustic and mechanical properties,and are widely used in the fields of reaction catalysis,energy storage,biosensing,drug transport and biotherapy.With the wide application of microfluidic technology,the combination of nanomaterials and microfluidic technology provides a new direction for research.In the field of sensors,the combination of microfluidic technology and nanomaterials further expands the application of sensors,which have the characteristics of high sensitivity,real-time performance and small size compared with traditional sensors.In particular,microfluidic optical sensors based on the optical properties of nanomaterials have become a focus of attention due to their ability to resist electromagnetic interference and corrosion in extremely harsh environments.This paper focuses on polarization absorption characteristics of Au films materials and its application in microfluidics.The research content is mainly divided into three parts:First,common preparation methods and characterization of Au films materials.Au films with different thickness were prepared by low vacuum sputtering and characterized by atomic force microscopy（AFM）and scanning electron microscopy（SEM）.The characterization results showed that Au film material with uniform particle size and gap was formed on the surface of quartz sheet.Second,the polarization absorption properties of Au films materials are studied.Based on Maxwell equations and reflection law,the theory of total internal reflection,multilayer film theory,surface plasmon resonance（SPR）effect and reflection coupling model are discussed,and the theoretical conditions of polarization absorption are expounded.The experimental parameters of polarization absorption characteristics are simulated to study the factors affecting polarization absorption characteristics and optimize the experimental results.The polarization absorption experiments of gold film with different thicknesses under the condition of total internal reflection were carried out to compare the polarization absorption differences under different thicknesses.Using the software theory simulation,the model in-depth analysis of the experimental results.The results show that the SPR effect occurs on the surface of Au nanomembranes with thickness of 35nm,and the absorption of TM wave is stronger than that of TE wave.The LSPR effect occurs on the surface of thin Au nanofilms,and the surface plasma waves are confined to Au NPs group and do not propagate along the metal surface.The absorption of TE wave is strong,but the absorption of TM wave is weak.Third,polarization absorption properties are applied to optical refractive index sensors.A microfluidic refractive index sensing system based on polarization characteristics of Au nano films materials was successfully designed.The sensor system has a wide-band response（200-1000 nm）over a wide incidence Angle（-10°to 25°）,and can sensitively identify subtle changes in the refractive index of the liquid.The detection sensitivity of the microfluidic refractive index sensor system is as high as 2.7×10⁵ m V/RIU,and the detection limit is as low as 3.7×10^-6.It can detect the refractive index changes caused by slight liquid pressure or flow rate,and has the advantages of high sensitivity,no mark,low detection limit,stable performance and real-time monitoring.To sum up,the polarization absorption characteristics of Au films materials under the condition of total internal reflection were studied in this topic,and based on this,a microfluidic refractive index sensing system was designed which can detect the optical refractive index of media quickly,real-time,nondestructive and labeling free.The research content of this subject provides an optimization scheme of refractive index detection,which lays a foundation for the application of refractive index sensor in the field of microfluidics.