Gold Nanofingers for Molecule Trapping and Detection

Abstract

Here we demonstrate a molecular trap structure that can be formed to capture analyte molecules in solution for detection and identification. The structure is based on gold-coated nanoscale polymer fingers made by nanoimprinting technique. The nanofingers are flexible and their tips can be brought together to trap molecules, while at the same time the gold-coated fingertips form a reliable Raman hot spot for molecule detection and identification based on surface enhanced Raman spectroscopy (SERS). The molecule self-limiting gap size control between fingertips ensures ultimate SERS enhancement for sensitive molecule detection. Furthermore, these type of structures, resulting from top-down meeting self-assembly, can be generalized for other applications, such as plasmonics, meta-materials, and other nanophotonic systems.

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

“…34 The obtained EF was 1.3 • 10 , see calculation details in supporting information. We then showed experimentally that O 2 -plasma process and Cr adhesion layers can be used to improve the SERS signal intensity and reduce the contribution from the Si surface contaminants.…”

“…Various NP arrays using e-beam lithography 32 , anodized aluminum oxide templates 33,35 , nanoimprinting 34 , oxygen-plasma-stripping-of-photoresist technique 36 , ion milling 37 , interference lithography 38,40 , and coating of multi-walled carbon nanotubes 39 have been reported. Recently, we have developed a new method to fabricate wafer scale Ag-capped Si nanopillar (Ag NP) SERS substrates utilizing maskless lithography.…”

“…These Ag NP substrates are capable of producing high E-field enhancement while the SERS signal uniformity remains relatively stable across a large (> cm 2 ) substrate surface area. 34,41 Since the NP fabrication process is essentially based on two simple and cost-effective steps, it opens new possibilities to tailor materials at the nanometer scale without the use of expensive lithographic tools.…”

Laser printing hierarchical structures with the aid of controlled capillary-driven self-assembly

“…These kinds of bioinspired adhesive filaments can be developed in various technical applications. As an example, the capillary force-assembled flexible nanofingers can be creatively used to form hot spots for molecule detection and identification based on surface-enhanced Raman spectroscopy (31,32). Although optical tweezers are able to manipulate small objects with different sizes ranging from tens of nanometers to micrometers, a substantial mechanical gripper is still desired in the absence of an energy beam and free of possible harm to living samples or influences to chemical reactions.…”

Patterning via self-organization and self-folding: Beyond conventional lithography

“…Although capillary forces can self-assemble freestanding rigid structures by attracting fl oating objects (e.g., breakfast cereal in the "Cheerios effect"), 17 , 18 here, we focus on capillary forces that deform micro-/nanostructures attached to a substrate. This approach, which allows greater structural complexity from features defi ned lithographically, has been utilized for microparticle trapping and release ( Figure 2g-h ), molecule trapping and detection ( Figure 2i-j ), 23 and whitening by surfaces that scatter light ( Figure 2m-n ). 24 Self-folding has been used in various applications, including self-folding robots ( Figure 3 a-b ), 25 microgrippers ( Figure 3d-f ), 26 solar cells, 27 and origami antennas.…”