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Sensors (Basel). 2008 Jan 21;8(1):171-184.

Chemical Sensing Sensitivity of Long-Period Grating Sensor Enhanced by Colloidal Gold Nanoparticles.

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Department of Physics, National Chung Cheng University, 168 University Road, Chia-Yi 621, Taiwan.
Department of Construction Engineering, National Yunlin University of Science and Technology, Yun-Lin 640, Taiwan.


A simple and effective method is proposed to improve spectral sensitivity anddetection limit of long period gratings for refractive index or chemical sensing, where thegrating surface is modified by a monolayer of colloidal gold nanoparticles. Thetransmission spectra and optical properties of gold nanospheres vary with the differentrefractive index of the environment near the surface of gold nanospheres. The sensorresponse of gold colloids increases linearly with solvents of increasing refractive index.The results for the measurement of sucrose and sodium chloride solutions are reported,which show that this type of sensor can provide a limiting resolution of ~10-3 to ~10-4 forrefractive indices in the range of 1.34 to 1.39 and a noticeable increase in detection limit ofrefractive index to external medium.


Spectral sensitivity; colloidal gold nanoparticles; localized surface plasmon resonance.; long-period grating; refractive index

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