In a SPR sensor, a glass slide is coated with a metal film, whose thicknesses, density and dielectric constant deadly affect
the measurement sensitivity and precision in bio-detection. The optimum thickness of gold film used in SPR is between
40nm and 50nm without adhesive film, according to calculations based on multilayer reflection model cited in large
numbers of literatures. But experimental study on the optimum film parameters are still lacking attribute to the limitation
of film coating technology and high-precision thickness measurement technology. The optimum gold film thickness is
not 45nm observed in our SPR bio-detection, and the property of adhesive film which is needed for enhancing the
adhesion of metal film affects the SPR responsive bandwidth and minimum reflectivity. The experiment study on the
sensor gold film and the property of adhesive film for SPR sensor are described in this paper using high precision SPR
detection system, X-ray diffraction and magnetron sputtering technology. The optimum thickness for single gold film is
44nm and is 42nm for gold film with 2.4nm Cr adhesive layer. A new estimating factor is proposed to evaluate the
quality and resolution of metallic film.
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