THE FABRICATION OF OPTICAL HOLE–ARRAYS FOR USE IN THE ATTO-LITER TITER PLATE DEVICE FOR SINGLE MOLECULE DETECTION (original) (raw)
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Atto-Liter Periodical Cavities for Optical Molecular Detection
IEEE Sensors, 2005., 2005
A process technology for fabrication of high quality nano-hole arrays in thin gold layers on glass substrates, suitable for biomolecular applications is presented. Making use of a bi-layer resist system, electron-beam lithography and a lift-off technique, different arrays of square-shaped nano-holes have been obtained. The holes dimensions are between 100nm and 200nm, with different lattice constants in each case. The arrays were furthermore optically characterized, showing uniformity and increased intensity of the out-coming light. I. 0-7803-9056-3/05/$20.00
Nano-hole Arrays in Thin Au/Pd Film on Glass, for High Speed Molecular Analysis
2006 5th IEEE Conference on Sensors, 2006
We present an improved process technology based on e-beam lithography and lift-off technique, for fabrication of different nano-hole arrays in optically thick gold/palladium (Au/Pd=60/40) layers on transparent substrates. Every hole serves as a reaction chamber for bio-molecular analysis (e.g. antibody/antigen recognition), as part of a novel atto-liter titer plate device. The optical characterization of the hole-arrays is pursued, both for the transmission of the light and the fluorescence signal through the holes. Array structures with square and hexagonal holes' distribution, with the holediameters between 150nm and 200nm and periodicity of 600nm and 900nm are fabricated in 200nm thick layer of gold/palladium alloy on glass. The spectrum of the transmitted light through the hexagonally distributed nano-holes compared to the one of the square distributed nano-holes shows a 20% of light enhancement. Applying Rhodamine G6 solution (0.05mM) on top of the arrays reveals a nine time increased fluorescent signal.
Nanohole arrays in chemical analysis: manufacturing methods and applications
The Analyst, 2010
Since the last decade, nanohole arrays have emerged from an interesting optical phenomenon to the development of applications in photophysical studies, photovoltaics and as a sensing template for chemical and biological analyses. Numerous methodologies have been designed to manufacture nanohole arrays, including the use of focus ion beam milling, soft-imprint lithography, colloidal lithography and, more recently, modified nanosphere lithography (NSL). With NSL or colloidal lithography, the experimental conditions control the density of the nanosphere mask and, thus, the aspect of the nanohole arrays. Low surface coverage of the nanosphere mask produces disordered nanoholes. Ordered nanohole arrays are obtained with a densely packed nanosphere mask in combination with electrochemical deposition of the metal, glancing angle deposition (GLAD) or etching of the nanospheres prior to metal deposition. A review of these methodologies is presented here with an emphasis on the optical properties of nanoholes interesting in analytical chemistry. In particular, applications of these novel plasmonic materials will be demonstrated as substrates for a localized surface plasmon resonance (LSPR), Surface Plasmon Resonance (SPR), surface enhanced Raman spectroscopy (SERS), and in electrochemistry with nano-patterned electrodes.
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A high-throughput optical biosensing technique is proposed and demonstrated. This hybrid technique combines optical transmission of nanoholes with colorimetric silver staining. The size and spacing of the nanoholes are chosen so that individual nanoholes can be independently resolved in massive parallel using an ordinary transmission optical microscope, and, in place of determining a spectral shift, the brightness of each nanohole is recorded to greatly simplify the readout. Each nanohole then acts as an independent sensor, and the blocking of nanohole optical transmission by enzymatic silver staining defines the specific detection of a biological agent. Nearly 10000 nanoholes can be simultaneously monitored under the field of view of a typical microscope. As an initial proof of concept, biotinylated lysozyme (biotin-HEL) was used as a model analyte, giving a detection limit as low as 0.1 ng/mL.
Nanomaterials, 2022
Arrays of metal nano-holes have proved to be among of the most promising structures for applications in the field of nano-photonics and optoelectronics. Supporting both localized and propagating surface plasmons resonances, they are characterized by very high versatility thanks to the tunability of these modes, by means of the change of their periodicity, the size of the holes and metal composition. The interaction between different optical features can be exploited to modulate electromagnetic field distribution leading various hot-spots excitations on the metal surfaces. In this work, long range ordered arrays of nano-holes in thin gold films, with different geometrical characteristics, were fabricated by a modified nano-sphere lithography protocol, which allows precise control on holes’ dimensions together with the preservation of the order and of the pristine periodicity of the array. An in-depth analysis of the correlation between surface plasmon modes interference and its effec...
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We present the fabrication and optical characterization of plasmonic nanostructures consisting of nanohole arrays in two thin films, a metal and a dielectric. A novel method called mask-onmetal colloidal lithography is used to prepare high aspect ratio holes, providing efficient mass fabrication of stable structures with close to vertical walls and without the need for an adhesion layer under the metal. Our approach for understanding the transmission properties is based on solving the dispersions of the guided modes supported by the two films and calculating the influence from interference. The methodology is generic and can be extended to multilayered films. In particular, the influence from coupling to waveguide modes is discussed. We show that by rational design of structural dimensions it is possible to study only bonding surface plasmons and the associated hole transmission maximum.
Advanced Functional Materials, 2010
The discovery of EOT has stimulated a signifi cant amount of work aimed at the development of possible applications that takes full advantage of its properties. Surface plasmon resonance (SPR) chemical sensors based on PANHs platforms, for instance, provide several advantages relative to the commercial prism coupling device. [ 4,5 ] These include a smaller footprint, making them more suitable for miniaturization and integration in microfl uidics devices, and a simplifi ed optical geometry for normal transmission measurements, which enables high density multiplexing and imaging SPR. [ 6-9 ] Another area of application where PANHs can make an impact is on plasmonicenhanced photovoltaics. [ 10-12 ] The SPR of gold nanostructures allow an increase in the effi ciency of the photo-conversion process in the red-region, a range notorious poor for the current commercial solar cells. [ 13 ] Despite all these promising applications, most of the work with PANHs reported so far was realized using samples fabricated by either focused ion beam (FIB) milling or e-beam lithography. [ 14 ] These techniques allow precise tuning of the geometric parameters of the arrays. They also provide a high degree of control and sample-to-sample reproducibility of the fabricated structures. These properties make them ideal for proof-of-concepts and for systematic investigations that require fi ne control over the geometric parameters of the nanostructures. However, these nanofabrication techniques are suitable to pattern only small areas, and, as essentially serial methods, they are not practical for mass production. Hence, any possible implementation of applications based on EOT using PANHs requires a methodology for large area nanopatterning. Moreover, the distribution of PANHs on the substrate area would depend on the type of application. A large perforated area would be required for applications in photovoltaic, but microarrays of PANHs would be more suitable for biomedical applications, since it allows for multiplexing detection of bio-markers. [ 15,16 ] Several research groups have been dedicated to the development of methodologies for large area nanopatterning [ 17 ] and their application for the fabrication of PANHs. Among the
Toward all on chip optical detection in the few molecule regime
Biosensors and Bioelectronics, 2020
Integrated optics devices are one of the most promising technologies in many fields such as biosensing, optical monitoring, and portable devices. They provide several advantages such as unique sensitivity and the possibility of the well-established and developed silicon photonics technology. However some challenges still remain open, as the implementation of multiplex assay able to reach the single particle sensitivity. In this context, we propose a new design for a Si-based photonic structure that enables the realization of on chip sub-wavelength optical sources. The idea is based on the insertion of opportunely designed nanometric holes in the photonic circuit, which are available for analyte detection with high efficiency. We propose three different configurations in which both excitation and detection are obtained through the same waveguide thus simplifying the detection scheme and potentially enabling multiplexed detection. We proved the high confinement of the electromagnetic field in the holes both by theoretical modelling and spectroscopic measurements. We investigate the possibility of inserting an arbitrary number of optical sources by using a resonator and evaluate advantages and drawbacks of resonating and non-resonating solutions. Finally, we report the proof-of-concept experiment, where detection sensitivity down to single Quantum Dots is obtained by combining the novel design with fluorescence-based techniques. Importantly, the presented results are achieved by a simple modification of photonic sensing chips which are already on the market thus having an excellent translational perspective.
Large Area Nanohole Arrays for Sensing Fabricated by Interference Lithography
Sensors, 2019
Several fabrication techniques are recently used to produce a nanopattern for sensing, as focused ion beam milling (FIB), e-beam lithography (EBL), nanoimprinting, and soft lithography. Here, interference lithography is explored for the fabrication of large area nanohole arrays in metal films as an efficient, flexible, and scalable production method. The transmission spectra in air of the 1 cm2 substrate were evaluated to study the substrate behavior when hole-size, periodicity, and film thickness are varied, in order to elucidate the best sample for the most effective sensing performance. The efficiency of the nanohole array was tested for bulk sensing and compared with other platforms found in the literature. The sensitivity of ~1000 nm/RIU, achieved with an array periodicity in the visible range, exceeds near infrared (NIR) performances previously reported, and demonstrates that interference lithography is one of the best alternative to other expensive and time-consuming nanofabr...