Study On Biosensing Technology Based On Thermal Oxidation Porous Silicon Interference Effects

Porous silicon as sensitive materials has the characteristics of high spicific surface and activity. Its microstructure can be controlled by change preparation parameter of porous silicon. So, according to different applications,we can flexibly use porous silicon and it has high senstivity at room temperature. With these good characteristics, it is also a kind of attractive biological sensor materials. Because porous silicon has good biodegradation, biocompatibility and its pore size can be controlled and it has active covalent and noncovalent surface chemical properties. Therefore, this paper adopts p-Si as material, using electrochemical anodioxidation method to prepare porous silicon and then do thermal oxidative treatment. It can form thermal oxidative porous silicon with high stability and biosensing property.The main contents of this paper are as following:(1) In this paper,firstly, summarize the current studies situation of the preparation and application of porous silicon at home and abroad; Then, overview the development of biosensors and porous silicon biosensors. Put forward a biosensing technology based on thermal oxidation porous silicon interference.(2) Investigate the influences of electrochemical conditions on porosity and film thickness of porous silicon. It is shown that the porosity of porous silicon will firstly increase and then decrease with anodioxidation time and current density. The thickness of porous silicon with anodioxidation time and current density will be a linear relation. So, we can obtain the thickness we want by controlling anodioxidation time and current density.(3) Study the influences of electrochemical anodization conditions on interference and optical thickness (OT) and optimize the electrochemical anodization conditions by orthogonal test. The results show that the optical thickness will increase with the increasing of electrochemical anodization time, current density and HF concentration. When keep the anodization time for 30s, current density for 520mA/cm² and HF:C2H5OH for 2:1～5:2(V/V), the interference phenomenon will be excellent and optical thickness is up to about ⁷873nm.(4) We also do the qualitative and quantitative research of biosensors based on thermal oxidation porous silicon interference. It verifies that thermal oxidation porous silicon has good adsorption effect for biosomes and it has high sensitivity. The equilibrium time of absorbing immune serum is 40min and the minimum rabbit IgG concentration is 6.7×10^-7M interacting with immune serum diluting 5 times. Based on the optical thickness changes of antigen-antibody at thermal oxidation porous silicon, the equilibrium constants can be calculated accurately. Kd is 7.85×10^-6M,Ka is 1.27×10⁵M^-1. We also find that the optical thickness change valueΔOTf increase with addition concentration of rabbit IgG and the maximun rabbit IgG concentration is 3.35×10^-6M.