Study Of Polymer Bump Grating Biosensor

Optical polymer is widely used in the field of optical measurement with the ad-vantages of easy production, low cost, lightweight, and suitable for mass production,etc. To research polymer bump grating biosensors which can be used to detectimmunoassay and nucleic acid has an important significance in the development ofmedical instrumentation system.This paper proposes a new design of a polymer bump grating biosensor. Themain contents include: the choice of grating material and grating templates, thegrating etching techniques and method of grinding pressure molding process; theestablishment of a theoretical model, the choice of experimental equipment andconstruction of the experimental light path, the analysis of experimental results.The details of this article are listed as follows:Large quantities of PMMA rectangular phase gratings with the same gratingparameters and excellent performance were copied by using rectangular fused silicaphase grating as a template.According to the efficiency of the1st-order (plus or minus) and zero-orderdiffraction ratio is sensitive to the change of groove depth of the grating, biologicalmolecules were embedded in the grooves of micro-structure bump grating. Then, thebio-molecule information can be obtained by detecting the diffracted light intensityratio because the change of groove depth while biological reaction occurs in grooves.A measure theory of this polymer bump grating biosensor is obtained on the basis ofthe theories of this principle and the transmission of diffraction grating.The article also analyzed the influence of the grating structure parameters todiffraction efficiency from both isosceles trapezoid structure and trapezoid structure,and emphatically analyzed the influence of parameters (1,2, v) of trapezoidstructure and bio-molecule to the diffraction efficiency. Then, a optimized structureparameters were obtained. In the process of experiment, depth of grating groove was31m, grating constant was1.6m, optical wavelength was632.8nm, refractiveindex of polymer was1.586and two basic angles of trapezoid were152and 290, the duty-cycle was0.1.The experimental light path of this polymer bump grating biosensor was desi-gned based on the principle of the loss of1st-order and zero-order optical intensityare equal when they transmit to detector in the background. The optical intensity of1st-order and the zero-order was measured by CCD sensor and gray value of lightintensity was obtained by the MATHCAD software. The groove depth and the thick-ness of the bio-molecule were calculated, at the same time, the cause of errors betw-een the experimental value and the actual value was analyzed.For the experimental and theoretical can be more consistent, optical path of thepolymer bump grating biosensor was redesigned by ZEMAX software. And on thisbasis the most optimal structure of cylindrical lens which can diffuse laser spot intostrip spot and the best placement of the CCD sensor were obtained. The depth of thegrating grooves and the thickness of bio-molecule of the scalar polymer opticalbiosensor were measured more accurately by this experimental design.