Gold nanoplates as sensing material for plasmonic sensor of formic acid

The gold (Au) nanoplates were grown using seed mediated growth method on the substrate surface. This process consists of two-steps process; seeding and growth of the nanocrystals. The cation polymer namely poly-l-lysine (PLL) was deposited on the substrate to obtain high yield nanoplates before immersed into seed solution. The morphology image of Au nanoplates sample by FESEM shows the yield can be estimated up to 63 % over all area of substrate surface. The optical absorption has two peaks that are associated with transverse (t-SPR) and longitudinal LSPR (l-SPR) respectively. The gold nanoplates sample is tested into formic acid and it was found that their intensities and peak position were changed with the change of surrounding medium. Consequently, using an optical sensor system, variation concentration of formic acid solutions from 1 % to 50 % can be detected. The higher concentration of formic acids will damage the Au nanoplates samples.