Laminar Flow Microarray Patterning by Perpendicular Electrokinetic Focusing

This paper describes a method to pattern microarrays in a closed microfluidic device. Two perpendicular laminar flow streams can operate in terms to sequentially coat the surface of a flow-chamber with parallel lanes in two directions. Two perpendicular sample streams can be controlled in position and width by applying electrokinetic focusing, for which each of the two streams is sandwiched between two parallel laminar flow streams containing just a buffer solution. Electroosmotic flow allows a simple chip design without any moving parts being involved. With this device configuration it is possible to define an array of up to 169 spots on a surface area of 1 mm2

A novel parallel nanomixer for high-throughput single-molecule fluorescence detection

This paper introduces a novel fluidic device based on syringe-driven flow of fluorescent species through a parallel array of nanochannels, in which the geometrical confinement enables long observation times of non-immobilized\ud molecules. Extremely low flow rates are achieved by operating the array of nanochannels in parallel with a larger microchannel. The addition of a second microfluidic inlet allows for mixing different species in a well-defined volume,\ud enabling the study of irreversible reactions such as DNA synthesis in real-time using single-molecule fluorescence resonance energy transfer. Devices are fabricated in glass with the purpose of high-throughput single-molecule\ud fluorescence detection

Combined Lab-on-a-Chip and microarray approach for biomolecular interaction sensing using surface plasmon resonance imaging

Surface plasmon resonance imaging (SPR) is a well-established label-free detection technique for real-time biomolecular interaction measurements. An integrated LOC sensing system with fluidic control for sample movement to specific locations on microarray surface in combination with SPR imaging is demonstrated by the measurements of human IgG and anti-IgG interactions from 24 patterned regions.\u

Partial reduction of anthracene by cold field emission in liquid in a microreactor with an integrated planar microstructured electrode

We report a novel microreactor with a photolithographically defined integrated electrode containing micro tips that serve as emission points for solvated electrons into liquid n-hexane in a microfluidic channel. The implementation of sharp electrode tips permits to extract electrons from the electrode material at relatively low voltages. The electric field distribution in the gap between a planar patterned platinum microtip array and a planar rectangular counterelectrode is analyzed by a computational model. Cold field emission using these microdevices is experimentally verified, and the partial reduction of anthracene to 9,10-dihydroanthracene, via solvated electrons emitted in solutions with or without ethanol in n-hexane is investigated. It is found that in the current microreactor configuration, the majority of the products are products originating from coupling of ethanol fragments to, and/or oxidation of 9,10-dihydroanthracene at the platinum counterelectrode, leaving no detectable yield of the desired reduction product

Three-dimensional fractal geometry for gas permeation in microchannels

The novel concept of a microfluidic chip with an integrated three-dimensional fractal geometry with nanopores, acting as a gas transport membrane, is presented. The method of engineering the 3D fractal structure is based on a combination of anisotropic etching of silicon and corner lithography. The permeation of oxygen and carbon dioxide through the fractal membrane is measured and validated theoretically. The results show high permeation flux due to low resistance to mass transfer because of the hierarchical branched structure of the fractals, and the high number of the apertures. This approach offers an advantage of high surface to volume ratio and pores in the range of nanometers. The obtained results show that the gas permeation through the nanonozzles in the form of fractal geometry is remarkably enhanced in comparison to the commonly-used polydimethylsiloxane (PDMS) dense membrane. The developed chip is envisioned as an interesting alternative for gas-liquid contactors that require harsh conditions, such as microreactors or microdevices, for energy applications

Melt-Extrusion-Based Additive Manufacturing of Transparent Fused Silica Glass

In recent years, additive manufacturing (AM) of glass has attracted great interest in academia and industry, yet it is still mostly limited to liquid nanocomposite-based approaches for stereolithography, two-photon polymerization, or direct ink writing. Melt-extrusion-based processes, such as fused deposition modeling (FDM), which will allow facile manufacturing of large thin-walled components or simple multimaterial printing processes, are so far inaccessible for AM of transparent fused silica glass. Here, melt-extrusion-based AM of transparent fused silica is introduced by FDM and fused feedstock deposition (FFD) using thermoplastic silica nanocomposites that are converted to transparent glass using debinding and sintering. This will enable printing of previously inaccessible glass structures like high-aspect-ratio (>480) vessels with wall thicknesses down to 250 µm, delicate parts including overhanging features using polymer support structures, as well as dual extrusion for multicolored glasses

Continuous Quantum Measurement and the Quantum to Classical Transition

While ultimately they are described by quantum mechanics, macroscopic mechanical systems are nevertheless observed to follow the trajectories predicted by classical mechanics. Hence, in the regime defining macroscopic physics, the trajectories of the correct classical motion must emerge from quantum mechanics, a process referred to as the quantum to classical transition. Extending previous work [Bhattacharya, Habib, and Jacobs, Phys. Rev. Lett. {\bf 85}, 4852 (2000)], here we elucidate this transition in some detail, showing that once the measurement processes which affect all macroscopic systems are taken into account, quantum mechanics indeed predicts the emergence of classical motion. We derive inequalities that describe the parameter regime in which classical motion is obtained, and provide numerical examples. We also demonstrate two further important properties of the classical limit. First, that multiple observers all agree on the motion of an object, and second, that classical statistical inference may be used to correctly track the classical motion.Comment: 12 pages, 4 figures, Revtex

Continuous Quantum Measurement and the Emergence of Classical Chaos

We formulate the conditions under which the dynamics of a continuously measured quantum system becomes indistinguishable from that of the corresponding classical system. In particular, we demonstrate that even in a classically chaotic system the quantum state vector conditioned by the measurement remains localized and, under these conditions, follows a trajectory characterized by the classical Lyapunov exponent.Comment: 5 pages, multicol revte

Quantum nonlinear dynamics of continuously measured systems

Classical dynamics is formulated as a Hamiltonian flow on phase space, while quantum mechanics is formulated as a unitary dynamics in Hilbert space. These different formulations have made it difficult to directly compare quantum and classical nonlinear dynamics. Previous solutions have focussed on computing quantities associated with a statistical ensemble such as variance or entropy. However a more direct comparison would compare classical predictions to the quantum for continuous simultaneous measurement of position and momentum of a single system. In this paper we give a theory of such measurement and show that chaotic behaviour in classical systems can be reproduced by continuously measured quantum systems.Comment: 11 pages, REVTEX, 3 figure

The delta-function-kicked rotor: Momentum diffusion and the quantum-classical boundary

We investigate the quantum-classical transition in the delta-kicked rotor and the attainment of the classical limit in terms of measurement-induced state-localization. It is possible to study the transition by fixing the environmentally induced disturbance at a sufficiently small value, and examining the dynamics as the system is made more macroscopic. When the system action is relatively small, the dynamics is quantum mechanical and when the system action is sufficiently large there is a transition to classical behavior. The dynamics of the rotor in the region of transition, characterized by the late-time momentum diffusion coefficient, can be strikingly different from both the purely quantum and classical results. Remarkably, the early time diffusive behavior of the quantum system, even when different from its classical counterpart, is stabilized by the continuous measurement process. This shows that such measurements can succeed in extracting essentially quantum effects. The transition regime studied in this paper is accessible in ongoing experiments.Comment: 8 pages, 4 figures, revtex4 (revised version contains much more introductory material