Chemical Sensor Based on Surface Plasmon Resonance
Date Issued
2012
Date
2012
Author(s)
Lin, Min-Ping
Abstract
Numerous food safety incidents take place in recent years. For example, the 2008 Chinese milk scandal of which adulterated melamine was found in infant milk powder. Additionally, plasticizer (such as, bis(2-ethylhexyl) phthalate(DEHP), Benzyl butyl phthalate(BBP), dibutyl phthalate(DBP)) was used to replace palm oil in foods and drinks as a clouding agent in 2011, Taiwan. Therefore, to quickly and accurately characterize food or ingredients is extremely important for preventing damage from toxic substances. To approach this goal, there is a novel methodology of rapid detection by adopting surface-enhanced Raman scattering (SERS) effect on highly sensitive substrate. It will be powerful in detecting drugs and chemicals.
In this study, we develop a simple and low cost solution process to fabricate a novel Ag coated monodispersive silica colloid monolayer substrate to enhance Raman scattering signals of organic dyes, plasticizer and ketamine. By tuning the process parameters, a significant enhancement of Raman scattering by surface plasmon was observed. We also found that there is a relationship between the absorption wavelength of chemicals and the Raman excitation wavelength. The enhancement factor of Raman signal would be higher since the overlapped wavelength. The enhancement factor of organic dyes on our SERS substrate is 40,000 times. For the plasticizers, the enhancement factor of plasticizers on our SERS substrate is 21,000 times. A simple extraction method was used to remove the interference efficiently, leading to the lowest detecting limits 40 ppm and 20 ppm of plasticizer and ketamine respectively. Consequently, the developed SERS method with high sensitivity, low cost and quick detection in this study will be beneficial for the design and fabrication of functional devices and sensors.
Subjects
surface plasmon resonance
Raman scattering spectrum
self-assembly
organic dyes
plasticizers
ketamine
Type
thesis
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