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We have used protein cross-linking with the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and radiolytic footprinting coupled with high-resolution tandem mass spectrometry, to examine the structure of higher-plant PsbO when it is bound to Photosystem II. Twenty intramolecular cross-linked residue pairs were identified. On the basis of this cross-linking data, spinach PsbO was modeled using the Thermosynechococcus vulcanus PsbO structure as a template, with the cross-linking distance constraints incorporated using the MODELLER program. Our model of higher-plant PsbO identifies several differences between the spinach and cyanobacterial proteins. The N-terminal region is particularly interesting, as this region has been suggested to be important for oxygen evolution and for the specific binding of PsbO to Photosystem II. Additionally, using radiolytic mapping, we have identified regions on spinach PsbO that are shielded from the bulk solvent. These domains may represent regions on PsbO that interact with other components, as yet unidentified, of the photosystem.

Protein cross-linking and radiolytic footprinting coupled with high-resolution mass spectrometry were used to examine the structure of PsbP and PsbQ when they are bound to Photosystem II. In its bound state, the N-terminal 15-amino-acid residue domain of PsbP, which is unresolved in current crystal structures, interacts with domains in the C terminus of the protein. These interactions may serve to stabilize the structure of the N terminus and may facilitate PsbP binding and function. These interactions place strong structural constraints on the organization of PsbP when associated with the Photosystem II complex. Additionally, amino acid residues in the structurally unresolved loop 3A domain of PsbP ((90)K-(107)V), (93)Y and (96)K, are in close proximity (≤ 11.4 Å) to the N-terminal (1)E residue of PsbQ. These findings are the first, to our knowledge, to identify a putative region of interaction between these two components. Cross-linked domains within PsbQ were also identified, indicating that two PsbQ molecules can interact in higher plants in a manner similar to that observed by Liu et al. [(2014) Proc Natl Acad Sci 111(12):4638-4643] in cyanobacterial Photosystem II. This interaction is consistent with either intra-Photosystem II dimer or inter-Photosystem II dimer models in higher plants. Finally, OH(•) produced by synchrotron radiolysis of water was used to oxidatively modify surface residues on PsbP and PsbQ. Domains on the surface of both protein subunits were resistant to modification, indicating that they were shielded from water and appear to define buried regions that are in contact with other Photosystem II components.

In this research, a rapid prototype hydrodynamic focusing module with three multi-fluidic speed-modulating (MFSM) micropumps in micro-fluidic flow has been designed, fabricated, and characterized. The module comprises of three MFSM micropumps having the dimension of 33 � 25 � 5 mm to achieve hydrodynamic focusing and the stream modulation. Each micropump consists of top, middle and bottom including actuation/modulation source, PDMS/nickel-particle composite (PNPC) diaphragm and Tesla-type valve/chamber, respectively. Three MFSM micropumps share one pneumatic actuation source and two individual permanent magnet modulation sources which are located above the right and left diaphragms. Each permanent magnet is manually controlled by a screw. The PNPC diaphragm deflection is obtained by the external pneumatic force, and the permanent magnet limits the displacement resulting from the interaction between the magnetic field and the nickel particles of the PNPC diaphragm. Hydrodynamic focusing is realized by the flow rate control of two side micropumps with magnetic diaphragm displacement modulation. Analyses of the magnetic modulation field, the flow rate of the MFSM micropump, and the hydrodynamic focused stream modulation are presented. The individual micropump can pump DI water with a flow rate of about 107 μl/min, and the hydrodynamic focusing channel can achieve a flow rate of about 321 μl/min, under the frequency of 2 Hz. This research examines the modulation feasibility of hydrodynamic focused center stream by controlling the neighboring stream flow rate and this technique can be utilized for possible applications in lab-on-a-chip, micro total analysis system and point of care testing system.

Photosystem II uses water as an enzymatic substrate. It has been hypothesized that this water is vectored to the active site for water oxidation via water channels that lead from the surface of the protein complex to the Mn4O5Ca metal cluster. The radiolysis of water by synchrotron radiation produces amino acid residue-modifying OH• and is a powerful technique to identify regions of proteins that are in contact with water. In this study, we have used this technique to oxidatively modify buried amino acid residues in higher plant Photosystem II membranes. Fourier transform ion cyclotron resonance mass spectrometry was then used to identify these oxidized amino acid residues that were located in several core Photosystem II subunits (D1, D2, CP43, and CP47). While, as expected, the majority of the identified oxidized residues (≈75%) are located on the solvent-exposed surface of the complex, a number of buried residues on these proteins were also modified. These residues form groups which appear to lead from the surface of the complex to the Mn4O5Ca cluster. These residues may be in contact with putative water channels in the photosystem. These results are discussed within the context of a number of largely computational studies that have identified putative water channels in Photosystem II.

With recent increasing trend towards development of “easy to fabricate” and simple millifluidic systems that could provide required control as well as high throughput, we present here a demonstration of potential opportunities for controlled droplet/slug formation within a flow-focusing millifluidic chip. Numerical simulations supported by experimental evidence show that the millifluidic device provides similar control in slug formation as in the case of microfluidic devices. More specifically, our investigations reveal that the acquired slug volume depends on the squeezing volume (Vsqueeze) and blockage volume (Vblock) in the squeezing regime. While the squeezing volume (Vsqueeze) can be tuned by manipulating the flow rate of the continuous phase, the blockage volume (Vblock) depended only on the geometry of the focusing region. Based on numerical simulations, two millifluidic flow focusing channel designs to produce small slugs were suggested. The slugs were utilized for the synthesis of uniform copper nanoparticles. The findings are anticipated to have implications for a number fields ranging from fluid dynamics, lab-on-a-chip devices, chemical engineering, nanomaterials synthesis, protein crystallization to advanced drug delivery as well as chip fabrication.

The J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices (CAMD) is a 1.3 GeV synchrotron-radiation facility owned and operated by the State of Louisiana. Fifteen beamlines provide radiation for CAMD users and cover the spectral range from the far IR to X-rays of ca. 40 keV. Eleven of them receive radiation from bending magnets and four from a 7 T wavelength shifter. A wide range of basic and applied scientific experiments as well as microfabrication are performed at these beamlines. The nanomaterial synthesis and characterization laboratory at CAMD continues to add new instruments such as SQUID magnetometer (Quantum Deign MPMS XL5) and high precision microfluidic-based nanomaterials synthesis equipment complementing already available facilities. We have recently received NSF MRI funding for a multipole 7.5 T wiggler that will become operational in 2012. Generous equipment donations from the University of California at Riverside (Professor Jory Yarmoff) and the University of Bonn (ELSA facility) will provide users with two additional VUV beamlines in the near future.

The goal of this project is to build a miniaturized, user-friendly cytometry setup (Datta et al. in Microfluidic platform for education and research. COMS, Baton Rouge, 2008; Frische et al. in Development of an miniaturized flow cytometry setup for visual cell inspection and sorting. Baton Rouge, Project Report, 2008) by combining a customized, microfluidic device with visual microscope inspection to detect and extract specific cells from a continuous sample flow. We developed a cytological tool, based on the Coulter particle counter principle, using a microelectrode array patterned on a borosilicate glass chip as electrical detection set-up which is fully embedded into a polymeric multi-layer microfluidic stack. The detection takes place between pairs of coplanar Cr/Au microelectrodes by sensing an impedance change caused by particles continuously carried within a microfluidic channel across the detection area under laminar flow conditions. A wide frequency range available for counting provides information on cell size, membrane capacitance, cytoplasm conductivity and is potentially of interest for in-depth cell diagnostic e.g. to detect damaged or cancerous cells and select them for extraction and further in-depth analysis.

Integration of electronic wiring with microfluidic chips is an important process as it allows electrical interactions with the fluidic media, for example required for resistive and capacitive sensing. It is also necessary in order to implement various actuation and control mechanisms such as pumping, electrophoresis and temperature control. Typically electrical wire traces are added to microfabricated fluidic chips using metal deposition processes that are carried out after the fluidic chip has been fabricated. The process for adding the wiring is complicated and is limited to select metals that can be deposited by evaporation or sputtering. We present a single step method for integrating electrical wires into polymer microfluidic chips that are fabricated by a hot embossing process. This process can flexibly embed any kind of commercially available metal wire with a microfluidic chip and the wiring may be integrated to come into surface contact with the fluid or may be embedded in close proximity to (but insulated from)the fluid paths for example for local heating purposes. This method significantly reduces total processing time and is thus a valuable method for wire integration into polymer chips. We demonstrate two applications—a microelectrolysis chip and a heater chip that were fabricated using this methodology. The design, fabrication process and the initial test results are presented.

A novel fabrication method involving two-step sequential backside exposures utilizing Fraunhofer diffraction is developed in this work to overcome some of the limitations of the current micro-nozzle fabrication techniques in controlling the shape and the size of micro-nozzles. Shape and size of the fabricated micro-nozzles are compared with simulation results. Micro-nozzles with tip diameters varying from 0 to 158.1 μm and the base diameter varying from 167.2 to 360 μm are fabricated simultaneously side-by-side on the same substrate by varying the total exposure dosage from 3 to 6 J/cm2 utilizing multiple backside exposures through designed circular aperture and zone plate masks.

In a close collaboration the team of Micromotion, micro resist technology, BESSY, and LSU-CAMD have successfully mastered the challenges of LIGA production of ultra-precision microparts for Micro Harmonic Drive® gears. The complementary expertise ranging from design and application know-how to process research and technical support resulted in high quality LIGA microparts and superior Micro Harmonic Drive® gears taking advantages of the free 2D design capability and material choice. It is also an excellent example that through contributions from partners with different background and expertise LIGA precision parts can be produced with high quality and yield and for a market competitive price.

We present on a carbon nanoparticle-filled SU-8 photosensitive polymer nanocomposite for use in microelectromechanical systems (MEMS) or microsystems. Exposure and fabrication of the material was carried out using X-ray lithography. The polymer nanocomposite was studied for its electrical, thermal and mechanical characteristics. It was found that at low filler weight percentages, the SU-8 polymer became electrically and thermally conductive. A comparative study of the lithography performance of this functionalized SU-8 to pure SU-8 was also performed. It was determined that UV lithography of the PNC was not suitable for thick films and that by using X-rays, thick film high-aspect-ratio microstructures were achievable. Such results are favorable for many applications such as monolithically integrated polymeric micro-resistive heating elements and polymeric micro-heat sinks.

High aspect ratio nickel microfluidic columns were fabricated using the LiGA technique. The 2-m-long 50-mum-wide high aspect ratio columns will be the separation component of a handheld gas chromatograph device for detecting semivolatile and volatile compounds. As a first step, 600-mum-deep electrodeposited nickel columns were fabricated. The serpentine columns were sealed and pressure-flow rate characteristics compared with the theoretical values. The response of the sealed columns was studied by running methane gas plugs through uncoated columns with a flame ionization detector at the exit. Negligible flow-induced dispersion was observed in the sealed metal columns. Unretained peak widths of ~15 ms were measured, and the experimental pressure and flow rate distributions matched those predicted by established analytical models within plusmn2.5%. Columns were coated with OV-1 stationary phase using static coating methods. A mixture of four hydrocarbons C6, C8, C10, and C12 was separated in a coated 50 mum by 600 mum by 0.5 m column in less than 2 s at 70 degC

A 16-channel microfluidic chip with an integrated contact conductivity sensor array is presented. The microfluidic network consisted of 16 separation channels that were hot-embossed into polycarbonate (PC) using a high-precision micromilled metal master. All channels were 40 microm deep and 60 microm wide with an effective separation length of 40 mm. A gold (Au) sensor array was lithographically patterned onto a PC cover plate and assembled to the fluidic chip via thermal bonding in such a way that a pair of Au microelectrodes (60 microm wide with a 5 microm spacing) was incorporated into each of the 16 channels and served as independent contact conductivity detectors. The spacing between the corresponding fluidic reservoirs for each separation channel was set to 9 mm, which allowed for loading samples and buffers to all 40 reservoirs situated on the microchip in only five pipetting steps using an 8-channel pipettor. A printed circuit board (PCB) with platinum (Pt) wires was used to distribute the electrophoresis high-voltage to all reservoirs situated on the fluidic chip. Another PCB was used for collecting the conductivity signals from the patterned Au microelectrodes. The device performance was evaluated using microchip capillary zone electrophoresis (mu-CZE) of amino acid, peptide, and protein mixtures as well as oligonucleotides that were separated via microchip capillary electrochromatography (mu-CEC). The separations were performed with an electric field (E) of 90 V/cm and were completed in less than 4 min in all cases. The conductivity detection was carried out using a bipolar pulse voltage waveform with a pulse amplitude of +/-0.6 V and a frequency of 6.0 kHz. The conductivity sensor array concentration limit of detection (SNR = 3) was determined to be 7.1 microM for alanine. The separation efficiency was found to be 6.4 x 10(4), 2.0 x 10(3), 4.8 x 10(3), and 3.4 x 10(2) plates for the mu-CEC of the oligonucleotides and mu-CZE of the amino acids, peptides, and proteins, respectively, with an average channel-to-channel migration time reproducibility of 2.8%. The average resolution obtained for mu-CEC of the oligonucleotides and mu-CZE of the amino acids, peptides, and proteins was 4.6, 1.0, 0.9, and 1.0, respectively. To the best of our knowledge, this report is the first to describe a multichannel microchip electrophoresis device with integrated contact conductivity sensor array.

Since the early 1990s a variety of applications ranging from precision metallic, ceramic, or polymeric parts to complex devices for micro-fluidic and micro-optic applications have been discussed with the assumption that LIGA can either make a significant contribution or is the sole technology able to make these products. The question today is, have individual LIGA groups or even the entire LIGA community achieved this goal? Despite major investments, a lot of hard work from many students and researchers, and some promising “prototypes”, a true mass product made by direct LIGA, i.e., using X-ray lithography and electroplating, has still not entered the market. This paper will briefly present the current status of direct-LIGA technology and discuss some examples of commercialization efforts as well as prospects for high-volume production.

Polymeric microfluidic chips are an enabling component for cost-effective, point of care analytical devices for pharmaceutical, agriculture, health, biological and medical applications. The microfluidic structures can be completed with active elements like pumps and valves as well as sensor components for more complex so called total analysis systems. Often, systems are designed as reader and disposable cartridge where the fluidic structures are simple devices that will be inserted into the reader, which executes the analytical protocol and displays the information in digital form, and disposed after completion of the analysis. In this paper, a hybrid fabrication approach was employed to build a polymeric microfluidic device, so-called sweatstick, suitable for collecting small, precise amounts (600 μl) of human sweat, which were further analyzed for the amount of calcium ions indicating bone mass loss. The device was assembled from different parts fabricated by ultra deep X-ray lithography, precision micro-milling, and molding. Surface treatment of liquid exposed surfaces by oxygen plasma ensures hydrophilic behavior and proper capillary action. Preliminary testing of the device was performed by collecting defined amounts of sweat simulant and determining the calcium ion content using a fluorescent technique. The results for low calcium ion concentration typical for human sweat were excellent and repeatable with variation less than 5% demonstrating the ability to perform indirect bone loss measurements.

Gas chromatography (GC) is one of the most widespread techniques used in laboratories as a way to separate and analyze complex mixtures of volatile and semi-volatile compounds. The main advantage of miniaturization of these systems is the increased performance due to the reduced time for analysis and reduced fabrication cost of the complex pneumatic flow system. In this paper advanced design ideas and fabrication processes to facilitate integration of the sample concentrator and the column will be presented. Using the LIGA process, 0.5- and 2-m-long, 50-μm-wide, and up to 600-μm-high aspect ratio metal GC separation columns with on-chip integrated sample injection and detection were fabricated. Initial experiments of coating these high aspect ratio columns show promising results when compared to simple tubular columns.

A novel approach to integrate densely packed CMOS devices with three-dimensional (3-D) microfluidic systems created at the wafer level using low temperature processes is introduced. The approach is based on low temperature (

Molding technologies associated with fabricating macro scale polymer components such as injection molding and hot embossing have been adapted with considerable success for fabrication of polymer microparts. While the basic principles of the process remain the same, the precision with which the processing parameters need to be controlled especially in the case of molding high aspect ratio (HAR) polymer microparts into polymer sheets is much greater than in the case of macro scale parts. It is seen that the bulk effects of the mold insert fixture and molding machine have a dominant influence on the molding parameters and that differences in material parameters such as the glass transition temperature (Tg) of polymer sheets are critical for the success and typically differ from sheet to sheet. This makes it very challenging to establish standard processing parameters for hot embossing of sheet polymers. In the course of this paper, a methodology for developing a hot embossing process for HAR microstructures based on known material properties and considering the cumulative behavior of mold, material, and machine will be presented. Using this method force–temperature–deflection curves were measured with the intent of fine tuning the hot embossing process. Tests were carried out for different materials using a dummy mold insert yielding information that could be directly transferred to the actual mold insert with minimum development time and no risk of damage to the actual microstructures.

Since 1995 CAMD has been offering exposure services, so called print shop for a variety of users interested in making precision High-Aspect-Ratio Microstructures (HARMST) for various application. Services have been expanded beyond only the print shop service in recent years and now include x-ray mask fabrication, substrate preparation for PMMA and SU- 8 resists, electroplating, finishing and molding. Metallic and polymeric parts are now routinely fabricated for precision engineering, micro-fluidic and micro-optic applications. This paper presents a brief overview of the actual status of LiGA services provided at CAMD including ongoing research efforts and examples of LiGA components for different applications.

Microfluidic is a field of considerable interest. While significant research has been carried out to develop microfluidic components, very little has been done to integrate the components into a complete working system. We present a flexible modular system platform that addresses the requirements of a complete microfluidic system. A microfluidic stack system is demonstrated with the layers of the stack being modular for specific functions. The stack and accompanying infrastructure provides an attractive platform for users to transition their design concepts into a working microfluidic system quickly with very little effort. The concept is demonstrated by using the system to carry out a chemilumiscence experiment. Details regarding the fabrication, assembly and experimental methods are presented.

Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°±2° before treatment to 32°±2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4kJ∕cm3, the contact angle of the sessile water drop changed from 95°±2° before radiation to 39°±3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applic...

In the last years the fabrication of micro components made from ceramic materials became more and more evident with respect to the pronounced chemical stability and the outstanding thermomechanical properties in comparison to plastics and metals. The aim of this work is the lithographic generation of ceramic microstructures avoiding an intermediate molding step using SU8 as pronounced sensitive resist matrix filled with fine ceramic powder in the submicron range. Focus of the research was to investigate the composite formation, patterning by x-ray lithography, developing, debinding and sintering to form stable ceramic parts. The addition of fine ceramic particles to low viscous liquids like SU8-10 leads to an increase of the viscosity. For a successful debinding and sintering a volume content of at least 40% ceramic is required resulting in a change of the viscosity from around 2 Pas up to a value of 1000 Pas at 25 °C and low shear rates. A modified casting procedure was developed for the formation of uniform resist films with a thickness around 300 μm. Optimized exposure and development parameters allow the fabrication of good quality resist structures that can be further transformed into ceramic structures by sintering. Details of the work and results will be presented and discussed in this paper.

A micro corona motor was fabricated using a membraneless built-on X-ray mask. Sharp stator electrodes of this motor ionize air molecules and ionized charges transfer onto the rotor surface, resulting in rotating rotor motions by Coulomb forces. For good performance, the stator’s electrodes should be wide (axial) and have sharp tips. Therefore, X-ray lithography was adopted for precise, high aspect ratio characteristics. To avoid the fabrication difficulty of a membrane X-ray mask, a built-on X-ray mask (conformal mask) technique was employed with negative toned SU-8 photoresist. SU-8 features X-ray fabrication compatibility, X-ray transparency and a large range of thickness. This technique may be suitable for fast fabrication of prototypes or very tall structures, which can be largely affected by printing gaps. For the X-ray built-on mask, 20 μm SU-8 was patterned and 8 μm gold absorber was electroplated on top of the 300 μm PMMA resist. Tests showed good quality pattern transfer from the SU-8 pattern and smooth sidewalls.

Micro bearing systems for Micro Electromechanical Systems (MEMS) have drawn attention for several decades as critical components for micro rotating machinery. Ideally, frictionless bearings are needed, and in practice, micro gas bearings approach the ideal. Typically, bearings function as a separate component, assembled onto sliding counterparts. However, in micro scale devices, assembly procedures are known to be very tedious and time consuming. This leads to the pursuit of single material monolithic structures. Critical issues arising from these approaches include: limitation of materials, friction, and reliability, among others. In this paper, new approaches have been pursued. Micro gas bearings were fabricated as a single component through X-ray lithography. A stainless steel gauge pin, machined to ultra precision, was used as a journal shaft. Simple and very easy assembly processes using self-aligning concepts were developed as an alternative method to conventional assembly. This article presents the design, fabrication, assembly, and testing of micro gas bearings.

A piezoelectric microjet has been fabricated and its working mechanism has been investigated. Considering different physical effects, the coupling models of the device are established and the key characteristics of the microjet are simulated by finite-element method. The dynamic displacement responses of the transducer under liquid-loading and unloading are calculated and compared. From numerical results, the coupling interactions dramatically damp the vibration amplitude of the transducer. However, the effects on the resonant frequencies of the structure are negligible, which will save much calculation work during further design optimization of the device. Based on the optimal design rules, the device has been fabricated and characterized.

With a view to meeting the requirements of high resolution microelectromechanical system applications, we studied high resolution (submicron scale) and high aspect ratio pattern fabrication through x-ray lithography. As a critical part of the x-ray lithography, an x-ray mask should have the properties of high resolution and being a thick absorber. To decrease the scattering effect, a 100 keV e-beam lithography system was used for the fabrication of the high resolution x-ray mask. 3 ?m thick PMMA (polymethylmethacrylate) resist was patterned and 2 ?m thick gold was electroplated onto the patterned resist to form the x-ray mask. Scanning electron microscopy analysis showed that the sidewall and pattern uniformity were sufficient and that the proximity effect did not play a significant role for the selected test patterns. 6 ?m thick PMMA resist was exposed by the x-ray mask; the experimental results proved the feasibility of reproducing submicron features. 0.5 ?m nested patterns with an aspect ratio of 12 were fabricated by this approach.

We have developed two fabrication routes for functional micro devices using SU-8/nanoparticle composites. In the first route, patterning of a 0.5% nanoparticle/SU-8 composite resulted in magnetic and luminescent polymeric microstructures. In the second route, a 42% nanoparticle/SU-8 composite was patterned followed by sintering to obtain free standing ceramic microstructures with aspect ratios as high as 16.

In this paper, a process for 200 μm high-aspect-ratio micro-optical (HARM) structures fabricated by deep X-ray lithography (DXRL) of polymethylislesuioane-based spin-on glass (SOG) thick films is presented. The SOG material used in the whole procedures is polymethylsilsesquioxane (GR650), which is a kind of sol-gel derived material and can be cured at a reasonable low temperature (75 °C). A technique to cast thick GR650 films was established in the overall process. After consolidation, the GR650 thick films were machined to reach 200 μm uniformly. Then, as negative resists, the GR650 thick films were patterned directly by DXRL. X-ray irradiated regions can be selectively retained with high structural resolution by development in an organic solvent, such as methanol. Parameter screening was done to find minimum and maximum doses needed for patterning/cross-linking, to vary development time, and to explore different film thickness. The whole process is a novel of technique to create HARM structures based on SOG materials without using molds. This technique can be extended to considerably larger structural heights. Surface and bulk compositions of the irradiated films were measured by XPS and Fourier transform infrared spectroscopy. Surface quality by roughness testing system (WYKO RST) was investigated to fabricate the microstructure with a high-accuracy surface.

Room and elevated temperature tensile, creep and high-cycle fatigue properties of electrodeposited LIGA Ni microsamples have been measured and are being used to predict the reliability of LIGA Ni MEMS structures. Tensile specimens with dimensions of hundreds of microns have been LIGA fabricated and characterized in terms of their underlying microstructure, elevated temperature tensile and creep strength and their high-cycle fatigue performance. The stiffness of these LIGA Ni structures was found to be reduced by the introduction of porosity during the plating process. The strength of these structures was observed to decrease dramatically at temperatures above 200 °C. At stresses significantly below the yield strength, substantial creep deformation was observed at moderately elevated temperatures. The fatigue life of the LIGA Ni microsamples increased with decreasing stress amplitude in a manner comparable to what has been reported for wrought Ni. An apparent fatigue limit was observed for the LIGA Ni microsamples, but the importance of underlying microstructure and component geometry on the fatigue life was also highlighted.

Many MEMS applications require multi-level microstructures in which two or more levels have to be aligned to each other in the processing. A passive alignment method based on a mechanical registration concept utilizing reference posts has been described in our early work [1]. An alignment accuracy of 1 μm for a two layers optical lithography has been achieved. In this paper the experimental results on improvement of the alignment accuracy and expanding this alignment method to multi-level X-ray or combined optical/X-ray lithography are presented.

The current status of the Louisiana State University Center for Advanced Microstructures and Devices electron storage ring, beamlines, and the scientific program are described.

In this paper, we report the first results from an in situ XANES experiment using a microreactor system for the wet chemical synthesis of Co nanoparticles. In this system, time resolution (in the order of milliseconds) is obtained by spatial resolution, i.e. by measuring spectra at various points along the microreactor.

Micromechanical milling has been shown to be a rapid and direct method for fabricating masks for deep x-ray lithography with lateral absorber features down to 10 micrometers. Conventional x-ray mask fabrication requires complex processes and equipment, and a faster and simpler method using micromechanical milling was investigated for larger microstructures for mesoscale applications. Micromilled x-ray masks consisting of a layered architecture of gold and titanium films on graphite yielded exposures in PMMA with accuracy and repeatability suitable for prototype purposes. A method for compensating milling tool radial runout was adapted, and the average accuracy of mask absorber features was 0.65 micrometers, with an average standard deviation of 0.55 micrometers. The milling process leaves some absorber burrs, and the absorber wall is tapered, which introduces an additional process bias. Mask fabrication by micromilling is fast and, therefore, less costly than conventional mask fabrication processes.

Micromechanical milling has been shown to be a rapid and direct method for the fabrication of structures with the geometry and size suitable for use as x-ray mask absorbers. While the micromilling process can not duplicate the size and resolution of absorber patterns created by high energy electron beam or optical lithography methods, micromilling can repeatedly create absorber line widths down to 10 micrometers, or less, with a one-sigma tolerance of 0.5 micrometers. A method for easily characterizing milling tool run out has been adapted so tool change out can be more routine. The milling process leaves some absorber burrs and the absorber is apparently tapered at the machined wall which introduce process biases, both of which add to exposure degradation. Nevertheless, based on work to date, it appears both of these effects can be reduced to acceptable limits.

Infectious diseases are a major global health burden accounting for approximately 15 million deaths annually, many from drug resistant pathogenic agents, with a significant number of cases occurring in developing countries.[1–7] In particular, the resurgence of tuberculosis (TB) has been accompanied by the rapid spread of multi-drug resistance TB (MDR-TB) resulting from Mycobacterium tuberculosis (Mtb) strains that fail to respond to the first-line drugs, rifampin and isoniazid. Currently

The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of time resolved particle growth within the millifluidic channel with flask-based reactions reveals that the particle size can be controlled better within millifluidic channels. Overall, the results indicate potential opportunities to utilize easy to fabricate millifluidic reactors for the synthesis of nanoparticles, as well as as for carrying out time resolved kinetic studies.

The focus of this paper is on the use of SUEX Thick Dry Film Sheet (TDFS) laminates which DJ DevCorp is developing as a thick resist material in optical and X-ray lithography. Preliminary thick dry film sheets up to 1mm thickness were successfully prepared and patterned at the CAMD X-ray beamlines and presented at HARMST 2007. Recently, new results have been published using SUEX resist sheets in UV lithography showing great market potential including plating molds for metal microparts, polymer MEMS, multilayer microfluidics structures, BioMEMS, medical devices, wafer level packaging processes, and displays. The SUEX TDFS are available in a range of thicknesses from 100μm to 1mm or more and are pre-cut into a number of standard wafer sizes. This new material is a modified epoxy formulation containing an antimony-free photo acid generator (PAG) prepared under a highly controlled solvent-less process which provides uniform coatings between two throw-away layers of protective polyester film. As part of our initial studies resist layers of 250, 500 and 1000μm were laminated onto regular silicon wafers using a hot roll laminator at a speed of 1ft/min at 75°C. The entire substrate preparation takes about 1 hour and with practice users can prepare up to 10 substrates in this time which are typically ready to use within 2 hours. In our efforts to develop a commercially viable product we have conducted experiments using standard equipment available at CAMD (Quintel UV aligner and CAMD XRLM 1 and 4 beamline). Initial X-ray exposure tests were done with a bottom dose ranging between 100 and 400 J/cm3 and a top/bottom dose ratio of less than 3 for sheets up to 2mm in thickness. Exposure time for typical conditions of the CAMD storage ring (ring current ranging between 100 and 160mA, beam lifetime of about 10hrs at 100mA ring current) is about 10-15min for a 4' wafer. After exposure the samples were immediately post exposure baked between 70°C and 110°C using a convection oven, taken out and cooled to RT then relaxed up to 3 days before development to reduce stress. Development was done in PGMEA for up to 3 hours for the 1000μm thick samples followed by a short IPA rinse and drying in air. Very high aspect ratios of 100 or more have been routinely patterned with nearly perfectly straight sidewalls (~1-1.5μm deviation for a 1mm tall structure) and excellent image fidelity.

Hybrid microchips containing high aspect ratio gas chromatograph (GC) columns with an integrated on-chip split injection and a flame ionization detector were developed. Two different column configurations, spiral and serpentine, both 1 m long by 50 μm wide and 500 μm tall, were fabricated out of electrodeposited nickel. The hybrid chip allowed injection plugs on the order of 1–2 ms, which lowered the height equivalent to theoretical plates (HETP) and allowed a comparison of system level band broadening between the two column configurations. The gas phase band broadening was estimated by measuring the flow characteristics and peak broadening of an unretained compound, and the results were compared with kinetic models. Experimental results show that both spiral and serpentine column layouts had similar flow and band broadening, suggesting that gas phase band broadening may be independent of column layout. The necessity for narrow injection bands for fast micro-chip chromatographic analysis was demonstrated, which emphasized the importance of component integration in designing powerful micro-analytical systems.

The fabrication and characterization of a novel cyclic olefin copolymer (COC) waveguide embedded in a poly(methyl methacrylate), PMMA, fluidic chip configured in a multi-channel format with an integrated monolithic prism for evanescent fluorescence excitation are reported. The fabrication approach allowed the embedded waveguide to be situated orthogonal to a series of fluidic channels within the PMMA wafer to sample fluorescent solutions in these channels using the evanescence properties of the waveguide. Construction of the device was achieved using several fabrication techniques including high precision micromilling, hot embossing and stenciling of a polymer melt to form the waveguide and coupling prism. A waveguide channel was fabricated in the fluidic chip's cover plate, also made from PMMA, and was loaded with a COC solution using a pre-cast poly(dimethylsiloxane), PDMS, stencil containing a prism-shaped recess. The PMMA substrate contained multiple channels (100 microm wide x 30 microm deep with a pitch of 100 microm) that were situated orthogonal to the waveguide to allow penetration of the evanescent field into the sampling solution. The optical properties of the waveguide in terms of its transmission properties and penetration depth of the evanescent field in the adjacent solution were evaluated. Finally, the device was used for laser-induced fluorescence evanescent excitation of a dye solution hydrodynamically flowing through multiple microfluidic channels in the chip and processed using a microscope equipped with a charge-coupled device (CCD) for parallel readout. The device and optical system were able to image 11 channels simultaneously with a limit-of-detection of 7.1 x 10(-20) mol at a signal-to-noise ratio of 2. The waveguide was simple to manufacture and could be scaled to illuminate much higher channel numbers making it appropriate for high-throughput measurements using evanescent excitation.

Metallic large area mold inserts (LAMIs) are essential for the replication of polymer microfluidic devices. Successful molding of micro- or nanoscale features over large areas is dependent on improving the dimensional control of the mold inserts, particularly those fabricated by electrodeposition using the LIGA or UV-LIGA processes. A systematic approach to controlling the internal stress of the nickel deposits, which was essential for predicting the final flatness of the LAMIs prior to electroplating, was carried out. The internal stress of the nickel deposits from a nickel sulfamate solution was estimated using a bent strip stress measurement method after maintaining electroplating chemicals and conditions and reducing contamination. Over-electroplating of the nickel LAMIs was performed on SU-8 electroplating molds on 150 mm diameter Si wafers. Detailed characterization of the nickel LAMIs to determine the relationship between the overall flatness of the LAMIs and the internal stress identified a suitable process window in terms of the current densities (10–20 mA/cm2) and the internal stress (−8.3 ∼ −3.0 MPa) for the high quality nickel LAMIs with an overall flatness of 100 μm.

This paper presents the status and the operation conditions of the 1.3 GeV storage ring at the Center for Advanced Microstructures and Devices (CAMD). An overview of existing beamlines with their relevant parameters is given and four beamlines that came into operation over the last two years are discussed in some detail.

Simple design of CAMD’s new infrared microspectroscopy beamline is presented. A pair of mirrors, planar and toroidal, is utilized for extracting infrared radiation from the conventional bending magnet port to a diamond window located outside of the shielding wall. Infrared radiation passed through the diamond window is then collimated by a small parabolic mirror, and fed into a Michelson interferometer. The Nicolet Nexus 670 FT‐IR spectrometer and the Continuum microscope serve as the end station for this infrared microspectroscopy beamline.

The purpose of this work is to establish a standard sensitivity calibration protocol for GMR (Giant MagnetoResistive) spin valve sensors using superparamagnetic particle embedded microprobes (SPEM). Comparing to other calibration methods, such as the use of MFM (Magnetic Force Microscope), sealed fluidic flow cells, current lines, etc., the proposed SPEM method has four major advantages: no magnetic background, a precisely controlled number of particles which is mostly single-layered, pristine GMR surface after calibration, and mass fabrication. The SPEM is made from a superparamagnetic particle embedded SU-8 post and a glass cantilever. It can calibrate the magnitude of GMR signals to the number of superparamagnetic particles by bringing a known number of single-layered particles close to the GMR surface while still keeping the GMR surface pristine for future biofunction.