On-Chip Surface-Based Detection with Nanohole Arrays

Department of Mechanical Engineering, University of Victoria, Victoria, British Columbia, Canada
Analytical Chemistry (Impact Factor: 5.64). 07/2007; 79(11):4094-100. DOI: 10.1021/ac070001a
Source: PubMed


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.

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Available from: Reuven Gordon, Aug 12, 2014
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    • "Currently, commercially available sensors are dominated by the conventional propagating surface plasmon resonance (PSPR)-based systems, such as utilizing noble metal films or prisms [5] [6]. Although the commercial PSPRbased sensors provide relatively high sensitivity, these systems require some complex and expensive equipments to couple and monitor lights, which hinders it's pervasive applications because it is difficult to be integrated into portable and low-cost microfluidic sensing devices [7]. Recently, the characteristics based on the extraordinary optical transmission (EOT) of the nanostructures has been utilized for biosensing applications [8]. "
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    ABSTRACT: A novel spatial and spectral selective plasmonic sensing based on the metal nanoslit arrays has been proposed and investigated theoretically, which shows a high performance in the multiplexing biomolecular detections. By properly tuning the geometric parameters of metal nanoslit arrays, the enhanced optical fields at different regions can be obtained selectively due to the excitation of SPP, cavity mode (CM), and their coupling effects. Simulation results show that the resonances of the metal nanoslit arrays at different spatial locations and different wavelengths can be achieved simultaneously. A relative bigger red-shift of 57 nm can be realized when a layer of biomolecular film is adsorbing at the slit walls, and the corresponding total intensity difference will be enhanced near 10 times compared to that at the top surface. In addition, when a BSA protein monolayer is adsorbing at slit walls with different slit widths, the corresponding wavelength shifts can reach to more than 80 nm by modulating the widths of the slit. The simulated results demonstrate that our designed metal nanoslit arrays can serve as a portable, low-cost biosensing with a high spatial and spectral selective performance.
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    • "Nanoplasmonic biosensors, which utilize plasmonic effects in engineered metal nanoparticles or nanostructures, have been proposed recently as a promising alternative to conventional SPR techniques, greatly broadening the range of potential technological applications [2]–[6]. Such nanoplasmonic biosensors eliminate the bulky prism-coupling geometry used in current SPR instruments, using instead a simple collinear transmission or reflection illumination geometry, which creates greater opportunities for sensor miniaturization, low-cost production, and integration with microfluidic platforms [7]. Scalability of the sensor footprint down to a few square micrometers also offers the possibility of massive multiplexing, which is difficult to achieve using previous SPR techniques [8]. "
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    ABSTRACT: Label-free biomolecular sensing is by far the most common and successful application area in the emerging field of nanoplasmonics. This review paper highlights the latest progress and achievements made in this area. Key aspects of the nanoplasmonic sensor development, including performance enhancement, efforts to increase multiplexing capacity, and the progress in sensor integration and miniaturization, are discussed.
    Preview · Article · Apr 2014 · IEEE Photonics Journal
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    • "SPR-based biosensors achieve higher sensitivities in different types of analyzes relative to other label-free sensors, such as in electrochemical [4], interferometric [5], and other systems [6] [7]. Also they present great potential for miniaturization [8], integration with microfluidics [9] and multiplexing detection capabilities [10]. Such characteristics are required for the implementation of lab-on-a-chip technologies [1]. "
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    ABSTRACT: Surface plasmon resonance platforms, based on arrays of nanoholes on gold films, were used to detect the binding of organic and biological molecules. Optical sensors were assembled using nanohole arrays with different resonance energies, tuned by adjusting the distance between the holes. A direct relationship between plasmon energy and bulk sensitivity to refractive index changes was verified experimentally. The highest sensitivity (ca. 463 nm/RIU) was obtained for the (1,0) SPP mode, excited on an array of nanoholes with 455 nm periodicity. Real-time monitoring of the specific biotin–streptavidin binding was also used to demonstrate the influence of transmitted light intensity and FWHM on the sensor performance.
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