The Study Of Preparation And Characteristics Of AuNPs-PDMS Composite Membrane Based On Chemical Methods

With the development of the scicence and technology,the new sensor has become a key research area in industrial and academic circles.The biosensor as a branch of these novel sensors attracts the attention of the world due to its broad application prospects and potentially huge profits.The research of new composite materials brings a variety of novel electrical,optical,magnetic and other excellent properties for sensitive elements of biosensors,which creates the necessary condition for the miniaturization,integration and high sensitivity of biosensors.Meanwhile,new composite materials contribute to innovative sensor structure and novel sensing mechanism,and achieve the rapid development of biosensors.In this thesis,based on the sensitive element of the surface stress biosensor,AuNPs-PDMS composite membranes are researched in detail.The first problem is how to tear off the composite membrane from the Si or glass substrate completely.In order to solve the problem,the substrate is silanized to improve the hydrophobicity of the substrate.As a result,the membrane can be peeled off from the substrate easily.Meanwhile,AuNPs-PDMS composite membranes are fabricated with two-step reduction.The process and principle of the preparation was analyzed.In the first step,AuNPs are embedded in the native PDMS membrane without external reducing agent,and the curing agent acts as the reducing agent.In the second step,HAuCl4 is reduced with glucose,and gold seeds formed in the first step induce AuNPs to deposit on the membrane continuously to achieve the AuNPs-PDMS composite membranes.Furthermore,the morphology characteristics of composite membranes are researched using UV-Vis absorption spectroscopy,field emission scanning electron microscope(FE-SEM),transmission electron microscope(TEM)and stylus profiling system.In addition,the electrical characteristics of composite membranes are researched.The I-V characteristics of the membrane under bending and unbending conditions are tested.Then the composite membrane is modified with 16-MHA,the resistance variation is studied during the modification process.The surface stress caused by molecular adsorption and chemical bonding leads to deflection of the membrane.Because of the microcracks in the surface of the membrane,tunneling and percolation phenomenon,the resistance value of the surface stress-based electrical test platform changes.The research of AuNPs-PDMS composite membrane in this thesis lays the foundation for the application of the membrane in surface stress-based biosensors.This research will contribute to the production and popularization of surface stress-based AuNPs-PDMS composite membrane biosensors.