Plasmonic sensors relying on nanoparticle arrays created by a template-directed dewetting process

Abstract

Label-free detection has promising applications in biomedical and analytical fields. Localized surface plasmon resonance (LSPR) of gold (Au) nanoparticles is sensitive to the dielectric constant of the surrounding environment. Therefore, the LSPR-based (or plasmonic) sensor is one of the most promising label-free sensing techniques. Here, we demonstrated that ordered arrays of Au nanoparticles fabricated by a template-directed dewetting process of the patterned Au film could be harnessed to construct high performance LSPR sensors. The size of the Au nanoparticles is determined by and can be simply adjusted through varying the thickness of the thermally evaporated Au film, and in turn the location of their LSPR peaks. The Au nanoparticles in the ordered array have a narrow size distribution, giving rise to sharp LSPR peaks needed for constructing high performance LSPR sensors. The LSPR sensors showed high sensitivity with a figure-of-merit value of 6.6 before they got saturated. Sensitive detection of DNA was used as an example to demonstrate the application potential of the LSPR-based sensors in biomedical fields.