Plasmon resonances of Ag capped Si nanopillars fabricated using mask-less lithography.

Localized surface plasmon resonances (LSPR) and plasmon couplings in Ag capped Si Nanopillar (Ag NP) structures are studied using 3D FEM simulations and dark-field scattering microscopy. Simulations show that a standalone Ag NP supports two LSPR modes, i.e.

Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents.

Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract.

Surface-enhanced Raman scattering on aluminum using near infrared and visible excitation.

We observed strong surface-enhanced Raman scattering on discontinuous nanostructured aluminum films using 785 nm excitation even though dielectric constants of this metal suggest plasmon supported spectroscopy in the ultraviolet range. The excitation of SERS correlates with plasmon resonances in the 1.3-2.

Carbon nanotube based stationary phases for microchip chromatography.

The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have already been demonstrated in more classical formats, for improved separation performance in gas and liquid chromatography, and for unique applications in solid phase extraction. Carbon nanotubes are now also entering the field of microfluidics, where there is a large potential to be able to provide integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels.

Nanofluidic devices with two pores in series for resistive-pulse sensing of single virus capsids.

We report fabrication and characterization of nanochannel devices with two nanopores in series for resistive-pulse sensing of hepatitis B virus (HBV) capsids. The nanochannel and two pores are patterned by electron beam lithography between two microchannels and etched by reactive ion etching. The two nanopores are 50-nm wide, 50-nm deep, and 40-nm long and are spaced 2.

Carbon nanotube based separation columns for high electrical field strengths in microchip electrochromatography.

Electrically insulated carbon nanotube (CNT) based separation columns have been fabricated that can withstand an electrical field strength of more than 2.0 kV cm(-1) without bubble formation from electrolysis. The carbon nanotubes were grown in a pillar array defined by photolithographic patterning of the catalyst layer used for synthesis of the nanotubes.

Refractive index sensor based on a 1D photonic crystal in a microfluidic channel.

A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with several ethanol solutions ranging from a purity of 96.

Electrophoresis microchip with integrated waveguides for simultaneous native UV fluorescence and absorbance detection.

Simultaneous label-free detection of UV absorbance and native UV-excited fluorescence in an electrophoresis microchip is presented. UV transparent integrated waveguides launch light at a wavelength of 254 nm from a mercury lamp along the length of a 1-mm long detection cell. Transmitted UV light is collected by another waveguide in the opposite end of the detection cell, while visible fluorescence is collected vertically through the lid of the chip.

Optical detection in microfluidic systems.

Optical detection schemes continue to be favoured for measurements in microfluidic systems. A selection of the latest progress mainly within the last two years is critically reviewed. Emphasis is on integrated solutions, such as planar waveguides, coupling schemes to the outside world, evanescent-wave based detectors and the field of optofluidics.

Underivatized cyclic olefin copolymer as substrate material and stationary phase for capillary and microchip electrochromatography.

We report, for the first time, the use of underivatized cyclic olefin copolymer (COC, more specifically: Topas) as the substrate material and the stationary phase for capillary and microchip electrochromatography (CEC), and demonstrate chromatographic separations without the need of coating procedures. Electroosmotic mobility measurements in a 25 microm id Topas capillary showed a significant cathodic EOF that is pH-dependent. The magnitude of the electroosmotic mobility is comparable to that found in glass substrates and other polymeric materials.

Microfabricated porous glass channels for electrokinetic separation devices.

Electrically insulated porous SiO2 channels for electrokinetic separation devices were fabricated based on a mask-less etching process for creation of high aspect ratio needles in silicon. The silicon needles are converted to SiO2 by oxidation and integrated within the interior of a fluidic channel network. The channels are about 5 microm high with a pore size of 0.

Recent developments in detection for microfluidic systems.

Microfluidic systems have become more and more important in the field of analytical chemistry. Detection methods on these microsystems are essential for the identification and quantification of chemical species that are being analyzed. This review concentrates on the latest developments of optical detection methods and mass spectrometry in conjunction with microfluidic systems.

Pure-silica optical waveguides, fiber couplers, and high-aspect ratio submicrometer channels for electrokinetic separation devices.

A new fabrication procedure for integration of ultraviolet transparent pure-silica planar waveguides, fiber couplers and high-aspect ratio submicrometer channels is presented. Only a single photolithographic mask step is required. The channels are 80-90 microm deep and the width can be reduced to about 0.

Effect of Joule heating on efficiency and performance for microchip-based and capillary-based electrophoretic separation systems: a closer look.

An attempt is made to revisit the main theoretical considerations concerning temperature effects ("Joule heating") in electro-driven separation systems, in particular lab-on-a-chip systems. Measurements of efficiencies in microfabricated devices under different Joule heating conditions are evaluated and compared to both theoretical models and measurements performed on conventional capillary systems. The widely accepted notion that planar microdevices are less susceptible to Joule heating effects is largely confirmed.

A microfluidic device with an integrated waveguide beam splitter for velocity measurements of flowing particles by Fourier transformation.

A microfabricated capillary electrophoresis device for velocity measurements of flowing particles is presented. It consists of a 1 x 128 planar waveguide beam splitter monolithically integrated with an electrically insulated fluidic channel network for fluorescence excitation at multiple points. Stray light rejection structures are included in order to suppress unwanted light between the detection regions.

Integration of polymer waveguides for optical detection in microfabricated chemical analysis systems.

Multimode polymer waveguides and fiber-to-waveguide couplers have been integrated with microfluidic channels by use of a single-mask-step procedure, which ensured self-alignment between the optics and the fluidics and allowed a fabrication and packaging time of only one day. Three fabrication procedures for obtaining hermetically sealed channels were investigated, and the spectrally resolved propagation loss (400-900 nm) of the integrated waveguides was determined for all three procedures. Two chemical absorbance cells with optical path lengths of 100 and 1000 microm were furthermore fabricated and characterized in terms of coupling loss, sensitivity, and limit of detection for measurements of the dye bromothymol blue.

Performance of an in-plane detection cell with integrated waveguides for UV/Vis absorbance measurements on microfluidic separation devices.

A microfluidic device with integrated waveguides and a long path length detection cell for UV/Vis absorbance detection is presented. The 750 microm U-cell detection geometry was evaluated in terms of its optical performance as well as its influence on efficiency for electrophoretic separations in the microdevice. Stray light was found to have a strong effect on both, the sensitivity of the detection and the available linear range.