On-Chip Surface-Based Detection with Nanohole Arrays

Abstract

A microfluidic device with integrated surface plasmon resonance (SPR) chemical and biological sensors based on arrays of nanoholes in gold films is demonstrated. Widespread use of SPR for surface analysis in laboratories has not translated to microfluidic analytical chip platforms, in part due to challenges associated with scaling down the optics and the surface area required for common reflection mode operation. The resonant enhancement of light transmission through subwavelength apertures in a metallic film suggests the use of nanohole arrays as miniaturized SPR-based sensing elements. The device presented here takes advantage of the unique properties of nanohole arrays: surface-based sensitivity; transmission mode operation; a relatively small footprint; and repeatability. Proof-of-concept measurements performed on-chip indicated a response to small changes in refractive index at the array surfaces. A sensitivity of 333 nm per refractive index unit was demonstrated with the integrated device. The device was also applied to detect spatial microfluidic concentration gradients and to monitor a biochemical affinity process involving the biotin-streptavidin system. Results indicate the efficacy of nanohole arrays as surface plasmon-based sensing elements in a microfluidic platform, adding unique surface-sensitive diagnostic capabilities to the existing suite of microfluidic-based analytical tools.

Development of Nanostructured Plasmonic Substrates for Enhanced Optical Biosensing

“…In contrast to the conventional reflection-type SPR biosensor, the momentum matching condition for plasmon resonance in zero-order transmission is given by the periodicity of the nanoholes and thus, prism coupling is not required [74]. Figure 12 demonstrates an experimental setup to measure the extraordinary optical transmission effect [75,76]. The metal film is deposited on a glass slide and the array is fabricated using focused ion beam milling.…”

Modeling and optimization of Au-GaAs plasmonic nanoslit array structures for enhanced near-infrared photodetector applications

“…[19][20][21][22] Field "hotspots" are produced via nanogap structures multiplying the magnitude of the electric field due to the plasmonic coupling between adjacent nanostructures. These hotspots can be harnessed for a variety of different applications, including surface-enhanced Raman spectroscopy, 23 single-molecule detection, [24][25][26][27] photovoltaics, [28][29][30][31][32][33][34][35] biosensing, [36][37][38][39][40][41][42] and photodetectors. 43,44 Prior work has investigated plasmonic effects in microscale interdigital electrodes, 45,46 but the current work extends the research to the nanoscale where plasmonic effects are more significant.…”

Use of thermally annealed multilayer gold nanoparticle films in combination analysis of localized surface plasmon resonance sensing and MALDI mass spectrometry

“…This LSPR wavelength shift, which is based on the change in the refractive index, can be examined by using UV-vis transmission or reflection spectroscopy. Several types of LSPR sensing platforms have been reported such as substrates on which immobilized NPs from a colloidal solution, [10][11][12][13][14][15][16][17][18] lithographically fabricated triangular-nanocrystal arrays, [19][20][21][22][23][24][25][26][27][28] nanohole arrays produced by ion-beam lithography, [29][30][31][32] and transparent substrates on which metal island films are fabricated by vapor deposition. [33][34][35][36][37][38][39] When LSPR sensing is conducted in transmission mode, it is known as transmission localized surface plasmon resonance (T-LSPR) sensing.…”