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Jun 2005

Volume 76, Issue 6, Articles (06xxxx)

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Nanoelectromechanical systems

K. L. Ekinci and M. L. Roukes

Rev. Sci. Instrum. 76, 061101 (2005); http://dx.doi.org/10.1063/1.1927327 (12 pages) | Cited 297 times

Online Publication Date: 26 May 2005

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Nanoelectromechanical systems (NEMS) are drawing interest from both technical and scientific communities. These are electromechanical systems, much like microelectromechanical systems, mostly operated in their resonant modes with dimensions in the deep submicron. In this size regime, they come with extremely high fundamental resonance frequencies, diminished active masses,and tolerable force constants; the quality (Q) factors of resonance are in the range Q ∼ 103–105—significantly higher than those of electrical resonant circuits. These attributes collectively make NEMS suitable for a multitude of technological applications such as ultrafast sensors, actuators, and signal processing components. Experimentally, NEMS are expected to open up investigations of phonon mediated mechanical processes and of the quantum behavior of mesoscopic mechanical systems. However, there still exist fundamental and technological challenges to NEMS optimization. In this review we shall provide a balanced introduction to NEMS by discussing the prospects and challenges in this rapidly developing field and outline an exciting emerging application, nanoelectromechanical mass detection.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
85.35.-p Nanoelectronic devices
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Introduction: Combinatorial instruments and techniques

Jaime C. Grunlan, Ali R. Mehrabi, and Radislav A. Potyrailo

Rev. Sci. Instrum. 76, 062101 (2005); http://dx.doi.org/10.1063/1.1921587 (1 page) | Cited 2 times

Online Publication Date: 18 May 2005

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Abstract Unavailable
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01.30.-y Physics literature and publications
07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)

High-throughput screening with micro-x-ray fluorescence

George J. Havrilla and Thomasin C. Miller

Rev. Sci. Instrum. 76, 062201 (2005); http://dx.doi.org/10.1063/1.1906063 (6 pages) | Cited 4 times

Online Publication Date: 17 May 2005

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Micro-x-ray fluorescence (MXRF) is a useful characterization tool for high-throughput screening of combinatorial libraries. Due to the increasing threat of use of chemical warfare (CW) agents both in military actions and against civilians by terrorist extremists, there is a strong push to improve existing methods and develop means for the detection of a broad spectrum of CW agents in a minimal amount of time to increase national security. This paper describes a combinatorial high-throughput screening technique for CW receptor discovery to aid in sensor development. MXRF can screen materials for elemental composition at the mesoscale level (tens to hundreds of micrometers). The key aspect of this work is the use of commercial MXRF instrumentation coupled with the inherent heteroatom elements within the target molecules of the combinatorial reaction to provide rapid and specific identification of lead species. The method is demonstrated by screening an 11-mer oligopeptide library for selective binding of the degradation products of the nerve agent VX. The identified oligopeptides can be used as selective molecular receptors for sensor development. The MXRF screening method is nondestructive, requires minimal sample preparation or special tags for analysis, and the screening time depends on the desired sensitivity.
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82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

High-throughput synthesis equipment applied to polymer research

Richard Hoogenboom and Ulrich S. Schubert

Rev. Sci. Instrum. 76, 062202 (2005); http://dx.doi.org/10.1063/1.1906090 (7 pages) | Cited 5 times

Online Publication Date: 17 May 2005

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To speed up synthetic polymer research, a workflow dedicated to automated polymer synthesis and characterization was developed. The workflow consists of several synthesis robots with online and offline analytical equipment. For screening of reaction parameters and for library synthesis, robots equipped with glass reactors and vortex agitation are applied that match very well the classical (small-scale) laboratory experiments. For the screening and library preparation also a microwave synthesizer can be used. For upscaling purposes and process development, a robot containing 100 mL tank reactors with mechanical stirring is utilized. This robot also offers the possibility to continuously feed reagents to the reactor and to operate in batch, semibatch or continuous mode.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
07.07.Tw Servo and control equipment; robots

Using open-source software technologies and standardized data structures to build advanced applications for high-throughput experimentation environments

Torsten Zech, Andreas Sundermann, Ringo Födisch, and Michael Saupe

Rev. Sci. Instrum. 76, 062203 (2005); http://dx.doi.org/10.1063/1.1906104 (12 pages) | Cited 1 time

Online Publication Date: 17 May 2005

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Herein we present a modular approach to a high-throughput experimentation software environment. Instead of a monolithic master system, small tools with a limited set of tasks are interconnected using standardized, self-descriptive data structures. This approach is highly flexible with respect to the rapidly changing needs of the scientists: Since the modules are isolated and intermodule communication is standardized, new components can be integrated without side effects. The developed software environment follows to a large extent the UNIX design philosophy and is heavily based on open-source software technologies that are used to solve specific tasks within the overall system to achieve high productivity in using the software for ambitious high-throughput experimentation programs. It is shown that the orchestration of the system significantly benefits from clear and standardized interface design based on hteML, the high-throughput experimentation markup language, an XML language for the description of high-throughput experimentation data and processes.
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07.05.Kf Data analysis: algorithms and implementation; data management

Combinatorial microelectrochemistry: Development and evaluation of an electrochemical robotic system

Thomas Erichsen, Sabine Reiter, Victoria Ryabova, Eva Maria Bonsen, Wolfgang Schuhmann, Wolfgang Märkle, Carsten Tittel, Günther Jung, and Bernd Speiser

Rev. Sci. Instrum. 76, 062204 (2005); http://dx.doi.org/10.1063/1.1906106 (11 pages) | Cited 19 times

Online Publication Date: 17 May 2005

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An electrochemical robotic system using standard microtiter plates as reaction wells for potentiostatic and galvanostatic electrosynthesis and high-throughput electroanalysis was conceived and realized using stepmotor driven positioning stages in combination with a flexible software. Electrode bundles specifically adapted to the experimental needs are accurately positioned in the wells of a microtiter plate followed by the automatic performance of sequences of electrosynthetic or electroanalytical techniques. The system allows us to work under inert-gas atmosphere, in aqueous and organic solvents, and to add or remove solutions by means of integrated syringe pumps. A specifically developed script language permits the user to perform very complex experimental sequences in the different wells of the microtiter plate. The hardware and software features of the developed electrochemical robotic system, the design of suitable electrode arrangements for electrosynthesis and electroanalytical techniques, as well as the reproducibility in aqueous and organic electrolytes are described. The performance of the system is demonstrated by redox screening of a Ru-complex library and by electrosynthesis with in situ analysis of a compound library.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
82.45.Rr Electroanalytical chemistry
82.80.Fk Electrochemical methods
82.45.Gj Electrolytes
82.45.Fk Electrodes
81.05.Cy Elemental semiconductors

Measurement of the flow velocity in unmagnetized plasmas by counter propagating ion-acoustic waves

J. X. Ma, Yang-fang Li, De-long Xiao, Jing-ju Li, and Yi-ren Li

Rev. Sci. Instrum. 76, 062205 (2005); http://dx.doi.org/10.1063/1.1924651 (5 pages) | Cited 9 times

Online Publication Date: 17 May 2005

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The diffusion velocity of an inhomogeneous unmagnetized plasma is measured by means of the phase velocities of ion-acoustic waves propagating along and against the direction of the plasma flow. Combined with the measurement of the plasma density distributions by usual Langmuir probes, the method is applied to measure the ambipolar diffusion coefficient and effective ion collision frequency in inhomogeneous plasmas formed in an asymmetrically discharged double-plasma device. Experimental results show that the measured flow velocities, diffusion coefficients, and effective collision frequencies are in agreement with ion-neutral collision dominated diffusion theory.
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52.70.−m
52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
52.25.Fi Transport properties

Techniques for combinatorial molecular beam epitaxy

Frank Tsui and Liang He

Rev. Sci. Instrum. 76, 062206 (2005); http://dx.doi.org/10.1063/1.1905967 (5 pages) | Cited 13 times

Online Publication Date: 18 May 2005

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Basic considerations for implementing combinatorial approach to molecular beam epitaxy (MBE) are discussed, focusing on the key issues relevant to conventional MBE synthesis using solid sources and characterization. The primary objective for implementing combinatorial approach is to make MBE do more, more able to carry out controlled and systematic work in large parameter space, without sacrificing any existing capabilities of conventional MBE. Methods for accomplishing this by integrating current instrumentation technology are described.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology

Combinatorial and high-throughput measurements of the modulus of thin polymer films

Christopher M. Stafford, Shu Guo, Christopher Harrison, and Martin Y. M. Chiang

Rev. Sci. Instrum. 76, 062207 (2005); http://dx.doi.org/10.1063/1.1906085 (5 pages) | Cited 32 times

Online Publication Date: 18 May 2005

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We describe the design and refinement of a high-throughput buckling-based metrology for ascertaining the mechanical properties (e.g., modulus) of combinatorial thin polymer film libraries. We provide critical details for the construction of a suitable strain stage, describe sample preparation, and highlight methods for high-throughput data acquisition and data analysis. To illustrate the combinatorial and high-throughput capability of this metrology, we prepare and evaluate films possessing a gradient in the elastic modulus and compare the results with an analytical expression derived from composite beam theory. Application of this metrology is very simple and practically any laboratory, academic or industrial, can perform such measurements with only modest investment in equipment. Although developed as a platform for investigating combinatorial libraries, researchers can take advantage of the high-throughput nature of this metrology to measure noncombinatorial film specimens as well.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
07.10.-h Mechanical instruments and equipment
68.60.Bs Mechanical and acoustical properties
81.40.Lm Deformation, plasticity, and creep
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
62.20.D- Elasticity

Library design using genetic algorithms for catalyst discovery and optimization

Frederic Clerc, Mourad Lengliz, David Farrusseng, Claude Mirodatos, Sílvia R. M. Pereira, and Ricco Rakotomalala

Rev. Sci. Instrum. 76, 062208 (2005); http://dx.doi.org/10.1063/1.1906086 (13 pages) | Cited 10 times

Online Publication Date: 18 May 2005

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This study reports a detailed investigation of catalyst library design by genetic algorithm (GA). A methodology for assessing GA configurations is described. Operators, which promote the optimization speed while being robust to noise and outliers, are revealed through statistical studies. The genetic algorithms were implemented in GA platform software called OptiCat, which enables the construction of custom-made workflows using a tool box of operators. Two separate studies were carried out (i) on a virtual benchmark and (ii) on real surface response which is derived from HT screening. Additionally, we report a methodology to model a complex surface response by binning the search space in small zones that are then independently modeled by linear regression. In contrast to artificial neural networks, this approach allows one to obtain an explicit model in an analogical form that can be further used in Excel or entered in OptiCat to perform simulations. While speeding the implementation of a hybrid algorithm combining a GA with a knowledge-based extraction engine is described, while speeding up the optimization process by means of virtual prescreening the hybrid GA enables one to open the “black-box” by providing knowledge as a set of association rules.
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02.60.Pn Numerical optimization

Investigation of machine compliance uniformity for nanoindentation screening of wafer-supported libraries

Oden L. Warren, Arpit Dwivedi, Thomas J. Wyrobek, Olugbenga O. Famodu, and Ichiro Takeuchi

Rev. Sci. Instrum. 76, 062209 (2005); http://dx.doi.org/10.1063/1.1906089 (6 pages) | Cited 4 times

Online Publication Date: 18 May 2005

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The reliability of nanoindentation results can depend critically on an accurate assessment of the machine compliance term. The common practice is to determine the machine compliance from a small reference specimen, then apply its value to a much larger wafer-supported library. The present study investigates the validity of this approach by thoroughly testing bare 76.2 mm diameter, 410 μm thick Si(100) wafers mounted on two vacuum chucks of different design. We find that the small-sample value of the machine compliance is adequate for the majority of the wafer, including areas directly over vacuum rings and a circular center port of ordinary dimensions. However, vacuum chucks with a tweezer slot should be avoided in combinatorial materials science applications. But even in the absence of a tweezer slot, it may be necessary to generate an accurate machine compliance map for the wafer perimeter if the thin-film library extends beyond the outermost vacuum ring to the wafer edge. The Young’s modulus and the hardness of silicon are found to be 169±3 GPa and 12.2±0.2 GPa, respectively, over well-mounted regions of the wafer; both values are in good agreement with the literature.
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81.05.Cy Elemental semiconductors
81.70.Bt Mechanical testing, impact tests, static and dynamic loads
68.60.-p Physical properties of thin films, nonelectronic
68.47.Fg Semiconductor surfaces
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.D- Elasticity
62.20.Qp Friction, tribology, and hardness
68.35.Gy Mechanical properties; surface strains

Evaluation of temperature-dependent adhesive performance via combinatorial probe tack measurements

Seung-ho Moon, Arnaud Chiche, Aaron M. Forster, Wenhua Zhang, and Christopher M. Stafford

Rev. Sci. Instrum. 76, 062210 (2005); http://dx.doi.org/10.1063/1.1906105 (6 pages) | Cited 1 time

Online Publication Date: 18 May 2005

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We describe the design and application of a temperature gradient probe tack apparatus for investigating the adhesive performance of model pressure-sensitive adhesives (PSAs). In particular, we illustrate a probe tack apparatus for studying the effect of temperature on three critical adhesion identifiers: adhesion energy, elongation at break, and debonding mechanisms. The measurement temperature is varied across the PSA film using a gradient temperature stage constructed from a transparent sapphire plate with a heating and cooling source positioned at opposite ends. The transparent substrate allows visualization of the contact area and debonding mechanisms during the test. The gradient temperature stage is integrated onto a motorized x-y stage, enabling a matrix of probe tack tests to be conducted across the PSA film at different sample temperatures. We use a spherical probe to evaluate the adhesive performance of a 150 μm thick model poly(styrene-b-isoprene-b-styrene) PSA film between a temperature range of 10 °C to 100 °C. We demonstrate that this apparatus is a viable combinatorial design for tack measurements and may be extended to more complicated two-dimensional gradient films.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
68.35.Np Adhesion
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity

Integration of MALDI-TOFMS as high-throughput screening tool into the workflow of combinatorial polymer research

Michael A. R. Meier and Ulrich S. Schubert

Rev. Sci. Instrum. 76, 062211 (2005); http://dx.doi.org/10.1063/1.1906123 (5 pages) | Cited 8 times

Online Publication Date: 18 May 2005

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The possibilities of an integration of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) as an high-throughput screening tool into the workflow of combinatorial materials research are discussed. A multiple layer sample preparation technique for MALDI is described in detail and its possibilities of automation and miniaturization are discussed. Automated MALDI sample preparation could be performed within an automated synthesizer robot as well as with an ink-jet printer. The first approach offers the possibility of online reaction monitoring, whereas the second approach gives the opportunity of applications in ultra-high-throughput environments. Moreover, an example of high-throughput screening of a polymerization reaction by MALDI-TOFMS is discussed.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
82.35.-x Polymers: properties; reactions; polymerization
68.43.Mn Adsorption kinetics
79.70.+q Field emission, ionization, evaporation, and desorption
81.20.-n Methods of materials synthesis and materials processing

Use of fluorescence for the high-throughput evaluation of synergistic thermal and photo stabilizer interactions in poly (vinyl chloride)

Chunyong Wu and Douglas A. Wicks

Rev. Sci. Instrum. 76, 062212 (2005); http://dx.doi.org/10.1063/1.1906124 (7 pages)

Online Publication Date: 18 May 2005

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The selection of thermal and photo stabilizers for poly (vinyl chloride) (PVC) using conventional methods is a time-consuming process. The high-throughput screening method developed in this research demonstrates rapid and efficient ways to quantify the effectiveness of PVC stabilizers with respect to raw plastic materials, stabilizers, levels of use, and testing conditions. An experimental protocol using liquid sampling and fluorescence measurement was developed to determine the effectiveness of formulations. This was used to evaluate the performance of stabilizers based on the change of fluorescence emission at 440 nm after thermal aging or ultraviolet (UV) radiation. The performance of PVC formulations using six different types of stabilizers was successfully mapped for both PVC resin and flexible PVC.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
78.55.Kz Solid organic materials
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

An electrode probe for high-throughput screening of electrochemical libraries

Rongzhong Jiang and Deryn Chu

Rev. Sci. Instrum. 76, 062213 (2005); http://dx.doi.org/10.1063/1.1904272 (5 pages) | Cited 1 time

Online Publication Date: 20 May 2005

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A pen-shaped O2 electrode probe is designed for high-throughput screening of electrochemical libraries. The electrode probe consists of a large-area O2 electrode and a cylindrical electrolyte sponge with a short cone tip for screening. This type of design can easily minimize the probe resistance contributed by the electrolyte. A zinc electrode library is generated using a nonautomated method to deposit metal zinc on a graphite plate. The zinc electrode library and the O2-electrode probe form an electrochemical library containing 128 micro zinc/air batteries. High-throughput screening of the zinc/air batteries are carried out by moving the tip of the electrode probe under constant potential (1.0 V) and measuring the current. A Gaussian distribution is used for statistical analysis of the experimental data. These data obtained with the combinatorial method have a relative standard deviation of 8.9% based on a nonautomated coating procedure. The O2 electrode probe is used to study the effect of addition of Cu in the anode on the performance of the zinc/air battery.
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82.45.Fk Electrodes
82.47.Cb Lead-acid, nickel-metal hydride and other batteries
82.45.Gj Electrolytes

High-throughput mechanical characterization of free-standing polymer films

Joe-Lahai Sormana, Santanu Chattopadhyay, and J. Carson Meredith

Rev. Sci. Instrum. 76, 062214 (2005); http://dx.doi.org/10.1063/1.1926967 (9 pages) | Cited 5 times

Online Publication Date: 20 May 2005

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In this article we review the design, construction, and operation of an instrument for high-throughput mechanical characterization (HTMECH) of polymer films. In particular, the HTMECH is applied here to free-standing polymer libraries with gradients in properties such as temperature and composition. Here, the goal is discovery of mechanical property relationships with polymer formulation and processing. However, HTMECH can also measure strain-rate libraries for uniform samples from near-static to meters-per-second (impact velocities). HTMECH measures force and deformation of film regions that undergo transverse biaxial loading by an instrumented thin contact tip. We demonstrate the salient features of mechanical models of the HTMECH assay and how they are employed to extract meaningful parameters from the raw data. The HTMECH instrument is compared and contrasted with conventional implementations of the dart impact and blister techniques.
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81.70.Bt Mechanical testing, impact tests, static and dynamic loads
07.10.Pz Instruments for strain, force, and torque
81.70.Cv Nondestructive testing: ultrasonic testing, photoacoustic testing
68.60.-p Physical properties of thin films, nonelectronic
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep

Design, fabrication, and application of a massively parallel single-bead microreactor system for high-throughput experimentation in heterogeneous catalysis

Torsten Zech, Gunilla Bohner, Oliver Laus, Jens Klein, and Michael Fischer

Rev. Sci. Instrum. 76, 062215 (2005); http://dx.doi.org/10.1063/1.1906088 (8 pages) | Cited 2 times

Online Publication Date: 23 May 2005

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We present a unique approach to high-throughput catalyst testing that is based on using individual beads in a massively parallel arrangement of microreaction chambers on a chip and describe its excellent scalability to very high numbers of parallel reaction chambers that have not been realized before in continuous flow applications. The reactor design benefits to a large extent from the principle of using individual, independent flow restrictors for equi-distribution of the fluid flow to the parallel reaction chambers. As a model reaction for the comparison of results obtained with a 384-parallel and a 625-parallel single-bead reactor, the selective CO oxidation in hydrogen is used. The same relative catalyst performances and catalytic trends can be measured in both reactor systems.
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07.10.Cm Micromechanical devices and systems
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.-b Specific chemical reactions; reaction mechanisms
81.70.-q Methods of materials testing and analysis

A parallel high-throughput approach to liquid crystal screening

Tobias Cull, Mark Goulding, and Mark Bradley

Rev. Sci. Instrum. 76, 062216 (2005); http://dx.doi.org/10.1063/1.1906125 (6 pages) | Cited 2 times

Online Publication Date: 23 May 2005

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A technique has been developed for the high-throughput (HT) parallel screening of liquid crystal (LC) phase transitions, using optical anisotropic effects observed only in the LC state to allow the determination of melting and clearing points. A camera was used to monitor optical changes observed in arrays of LC samples upon heating, when illuminated with plane polarized light and viewed through a second polarizer aligned perpendicular to the plane of polarized light. Data was processed using Image Pro Plus, extracting values for the melting point and clearing point of each sample in the array. When compared with literature and conventional differential scanning calorimetry the new technique was found to be in excellent agreement, establishing the technique as a viable HT alternative. The method was used to analyze a 75 formulation library prepared using liquid handling for HT clearing point determination, showing the scope and power of the technique in the analysis of larger libraries.
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61.30.-v Liquid crystals
64.70.M- Transitions in liquid crystals

Development of a spatially controllable chemical vapor deposition reactor with combinatorial processing capabilities

J. O. Choo, R. A. Adomaitis, L. Henn-Lecordier, Y. Cai, and G. W. Rubloff

Rev. Sci. Instrum. 76, 062217 (2005); http://dx.doi.org/10.1063/1.1906183 (10 pages) | Cited 5 times

Online Publication Date: 23 May 2005

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Most conventional chemical vapor deposition (CVD) systems do not have the spatial actuation and sensing capabilities necessary to control deposition uniformity or to intentionally induce nonuniform deposition patterns for single-wafer combinatorial CVD experiments. In an effort to address these limitations, a novel CVD reactor system has been developed that can explicitly control the spatial profile of gas-phase chemical composition across the wafer surface. This paper discusses the construction of a prototype reactor system featuring a three-zone, segmented showerhead design. Experiments are performed to assess the ability of this reactor system to deposit tungsten films by the hydrogen reduction process; segment-to-segment process recipes are controlled to deposit spatially nonuniform W films. The capabilities of this reactor system for materials discovery research are discussed.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.80.-d Chemical analysis and related physical methods of analysis
68.55.-a Thin film structure and morphology

High throughput oxide lattice engineering by parallel laser molecular-beam epitaxy and concurrent x-ray diffraction

M. Ohtani, M. Lippmaa, T. Ohnishi, and M. Kawasaki

Rev. Sci. Instrum. 76, 062218 (2005); http://dx.doi.org/10.1063/1.1926927 (7 pages) | Cited 3 times

Online Publication Date: 23 May 2005

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A laser molecular-beam epitaxy (LMBE) system for the fabrication of atomically controlled oxides superlattices and an x-ray diffractometer that measures spatially resolved x-ray diffraction spectra have been developed based on the concept of combinatorial methodology. The LMBE chamber has two moving masks, an automated target stage, a substrate heating laser, and an in situ scanning reflection high-energy electron diffraction system. The x-ray diffractometer with a curved monochromator and two-dimensional detector is used for rapid concurrent x-ray diffraction intensity mapping with the two axes of the detector corresponding to the diffraction angle and a position in the sample.
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81.15.Fg Pulsed laser ablation deposition
68.55.−a
07.85.Jy Diffractometers

Highly reliable 64-channel sequential and parallel tubular reactor system for high-throughput screening of heterogeneous catalysts

Kwang Seok Oh, Yong Ki Park, and Seong Ihl Woo

Rev. Sci. Instrum. 76, 062219 (2005); http://dx.doi.org/10.1063/1.1927076 (7 pages) | Cited 6 times

Online Publication Date: 23 May 2005

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Highly reliable 64-channel sequential and parallel tubular reactor for high-throughput screening of heterogeneous catalysts is constructed with stainless steel. In order to have a uniform flow rate at each channel, 64 capillaries are placed between the outlet of multiport valve and the inlet of each reactor. Flow rate can be controlled within ±1.5%. Flow distribution can be easily adjusted for sequential and parallel mode of operation. The reactor diameter is too big to have a uniform temperature distribution. Hence, the reactor body is separated into three radial zones and controlled independently with nine thermocouples. Temperature accuracy is ±0.5 °C at 300 °C and ±1 °C at 500 °C in sequential mode, while it is ±2.5 °C in the range of 250–500 °C in parallel mode. The temperature, flow rate, reaction sequence, and product analysis are controlled by LABVIEW™ software and monitored simultaneously with displaying a live graph. The accuracy in the conversion is ±2% at the level of 73% conversion when all reactors are loaded with same amount of catalyst. A quaternary catalyst library of 56 samples composed of Pt, Cu, Fe, and Co supported on AlSBA-15 (SBA-15 substituted with Al) are evaluated in the selective catalytic reduction of NO at various temperatures with our system. The most active compositions are rapidly screened at various temperatures.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.-b Specific chemical reactions; reaction mechanisms

Apparatus and methods for optical time-of-flight discrimination in combinatorial library analysis

Paul E. Henning, Anna Benko, Alan W. Schwabacher, Peter Geissinger, and Robert J. Olsson

Rev. Sci. Instrum. 76, 062220 (2005); http://dx.doi.org/10.1063/1.1906083 (8 pages) | Cited 5 times

Online Publication Date: 26 May 2005

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Our recently developed method for combinatorial synthesis leads efficiently to linear arrays, where the location of a compound in the array encodes its complete synthetic history. Such arrays prepared using an optical fiber as a linear support can be probed with a fiber-guided pulse, allowing evanescent interaction with fluorescent probe molecules at the core-cladding interface. Optical time-of-flight distinction among output signals of fluorescent regions distributed along the fiber is carried out, allowing for the measurement of the location of the emitting fluorescent probes. A unique two-fiber, double-evanescent process overcomes limitations in spatial discrimination, due to fluorescence decay times in comparison to the speed of light. Investigation of an array of 102 fluorescent regions is described, with discussion of its features and limitations.
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42.81.Bm Fabrication, cladding, and splicing

Plasma sputtering system for deposition of thin film combinatorial libraries

James S. Cooper, Guanghai Zhang, and Paul J. McGinn

Rev. Sci. Instrum. 76, 062221 (2005); http://dx.doi.org/10.1063/1.1921552 (7 pages) | Cited 5 times

Online Publication Date: 26 May 2005

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The design of a plasma sputtering system for the deposition of combinatorial libraries is described. A rotating carousel is used to position shadow masks between the targets and the substrate. Multilayer films are built up by depositing sequentially through various masks. Postdeposition annealing is used to promote interdiffusion of the layered structures. Either discrete or compositional gradient libraries can be deposited in this system. Samples appropriate for characterization with a scanning electrochemical microscope or a multichannel microelectrode array system can be produced. The properties of some deposited Pt–Ru films for fuel cell applications are described.
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81.15.Cd Deposition by sputtering
81.40.Gh Other heat and thermomechanical treatments
66.30.Ny Chemical interdiffusion; diffusion barriers
68.55.A- Nucleation and growth

Spectroscopic and imaging approaches for evaluation of properties of one-dimensional arrays of formulated polymeric materials fabricated in a combinatorial microextruder system

Radislav A. Potyrailo and Ronald J. Wroczynski

Rev. Sci. Instrum. 76, 062222 (2005); http://dx.doi.org/10.1063/1.1926987 (8 pages) | Cited 4 times

Online Publication Date: 1 June 2005

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We report optical spectroscopic and imaging approaches for the high-throughput nondestructive characterization of formulated polymeric materials fabricated as one-dimensional (1D) polymeric arrays. These materials are fabricated as 1–2 mm diameter fibers or 5–12-mm-wide by 0.3–1-mm-thick films using a combinatorial system that includes a microextruder (total barrel volume of 4.5 cm3) and microfeeders. Because our microextruder approach for fabrication of formulated polymeric materials requires ∼ 200 times less material compared to traditional scale extruders, it provides previously unavailable opportunities for characterization of extruded materials without their pelletization. Property changes in polymeric formulations are induced along the length of the 1D arrays by several approaches that include (1) variation in composition of 1D array during polymer microextrusion, (2) variation in processing conditions during polymer microextrusion, and (3) variation in exposure conditions of a performance test for different spatial regions along the length of the array. Polymeric 1D arrays are analyzed either in-line or off-line. In-line analysis is performed using spectroscopic luminescence emission and reflected light modes. For off-line analysis, 1D fiber and film arrays are coiled as helices and flat coils, respectively. Automated measurements of coiled 1D arrays are performed using modular scanning and imaging systems. The scanning system is based on a portable spectrograph and is coupled to an X‐Y translation stage to produce scans of 100 μm step size. The imaging system is operated in luminescence emission and reflected light modes. Our fabrication and analysis approaches significantly reduce the amount of material and energy needed and increase the speed of development of formulated polymeric materials by using approaches for characterization of coiled 1D polymeric arrays.
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81.70.Fy Nondestructive testing: optical methods
42.30.-d Imaging and optical processing
42.79.Ls Scanners, image intensifiers, and image converters
07.60.-j Optical instruments and equipment
78.55.Kz Solid organic materials
68.60.-p Physical properties of thin films, nonelectronic
81.10.Fq Growth from melts; zone melting and refining

Data management and visualization of x-ray diffraction spectra from thin film ternary composition spreads

I. Takeuchi, C. J. Long, O. O. Famodu, M. Murakami, J. Hattrick-Simpers, G. W. Rubloff, M. Stukowski, and K. Rajan

Rev. Sci. Instrum. 76, 062223 (2005); http://dx.doi.org/10.1063/1.1927079 (8 pages) | Cited 11 times

Online Publication Date: 1 June 2005

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We discuss techniques for managing and visualizing x-ray diffraction spectrum data for thin film composition spreads which map large fractions of ternary compositional phase diagrams. An in-house x-ray microdiffractometer is used to obtain spectra from over 500 different compositions on an individual spread. The MATLAB software is used to quickly organize the data and create various plots from which one can quickly grasp different information regarding structural and phase changes across the composition spreads. Such exercises are valuable in rapidly assessing the “overall” picture of the structural evolution across phase diagrams before focusing in on specific composition regions for detailed structural analysis. We have also shown that simple linear correlation analysis of the x-ray diffraction peak information (position, intensity and full width at half maximum) and physical properties such as magnetization can be used to obtain insight about the physical properties.
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61.05.cp X-ray diffraction
64.60.-i General studies of phase transitions
68.55.-a Thin film structure and morphology
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