Glass Capillary Arrays Research Articles

Glass capillary array supported membrane evaporator balancing heat and water management for double-side solar-driven interfacial evaporation

Efficient heat and water management are two important aspects for boosting solar-driven interfacial evaporation. Here, we develop a glass capillary array supported membrane evaporator (GCSE) to simultaneously achieve heat and water management. In the GCSE, a membrane at top regions enables photothermal conversion, and a glass capillary array at bottom regions serves as both water and heat management. The balance of heat and water management can be readily controlled by adjusting the number and height of glass capillary array. Moreover, the exposed bottom surface of GCSE further utilizes extra evaporation surface to boost evaporation. As a result, a high evaporation rate of 2.06 kg m−2 h−1 with an efficiency of 98.6% under 1 sun is achieved. Furthermore, the GCSE also exhibits potential applications in oil/water emulsion purification and seawater desalination.

A simulation study of a high-resolution fast neutron imaging detector based on liquid scintillator loaded capillaries

At present, the highest spatial resolution of a fast neutron imaging detector, mainly determined by the range of secondary particles generated by fast neutrons, is about hundreds of microns. In view of the above inherent spatial resolution limitation, a capillary-based scintillation detector that can improve the spatial resolution of fast neutron imaging by recording and reconstructing the recoil proton track was developed. The purpose of this paper is to develop a detector for recognizing recoil proton events, reconstructing particle track and improving the position resolution with track reconstruction method to reconstruct the position of interaction. The proposed detector consists of a 1000 × 1000 array of glass capillaries loaded with a high refractive index liquid scintillator. Each glass capillary was 10 μm in diameter and 5 cm in length. The recoil protons generated by the incident neutrons move within the detector and produce scintillation light within each capillary that they traverse. The light emitted from the capillary array can be recorded by employing an intensified CCD camera. We used Geant4 to simulate the detector performance and CERN ROOT analysis framework to record physical information of recoil proton, including position, energy deposition in each capillary and track length. Based on Hough transform, a rapid, computerized and efficient proton track reconstruction procedure was developed. The recoil proton events display a continuous extended structure. The track reconstruction algorithms can reconstruct individual track precisely, and when the counting rate was relatively low, the track reconstruction results were in good agreement with simulation data. Moreover, for intensive overlap conditions, this algorithm also reconstructs periphery tracks with high rate of accuracy.

The assembly of a polymer and metal nanoparticle coated glass capillary array for efficient solar desalination

A novel solar steam generator was fabricated by via assembling aof PDA and PDN coated glass capillary array (GCA) that possesses superior salt-resistance.

Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering.

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm-50 nm crystalline indium tin oxide or a 100 nm-150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure-function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

Molecular beam/infrared reflection-absorption spectroscopy apparatus for probing heterogeneously catalyzed reactions on functionalized and nanostructured model surfaces.

A new custom-designed ultrahigh vacuum (UHV) apparatus combining molecular beam techniques and in situ surface spectroscopy for reactivity measurements on complex nanostructured model surfaces is described. It has been specifically designed to study the mechanisms, kinetics, and dynamics of heterogeneously catalyzed reactions over well-defined model catalysts consisting of metal nanoparticles supported on thin oxide films epitaxially grown on metal single crystals. The reactivity studies can be performed in a broad pressure range starting from UHV up to the ambient pressure conditions. The UHV system includes (i) a preparation chamber providing the experimental techniques required for the preparation and structural characterization of single-crystal based model catalysts such as oxide supported metal particles or ordered oxide surfaces and (ii) the reaction chamber containing three molecular beams-two effusive and one supersonic, which are crossed at the same point on the sample surface, infrared reflection-absorption spectroscopy for the detection of surface-adsorbed species, and quadrupole mass spectrometry for gas phase analysis. The supersonic beam is generated in a pulsed supersonic expansion and can be modulated via a variable duty-cycle chopper. The effusive beams are produced by newly developed compact differentially pumped sources based on multichannel glass capillary arrays. Both effusive sources can be modulated by a vacuum-motor driven chopper and are capable of providing high flux and high purity beams. The apparatus contains an ambient pressure cell, which is connected to the preparation chamber via an in situ sample transfer system and provides an experimental possibility to study the reactivity of well-defined nanostructured model catalysts in a broad range of pressure conditions-up to ambient pressure-with the gas phase analysis based on gas chromatography. Additionally, a dedicated deposition chamber is connected to the preparation chamber, which is employed for the in situ functionalization of model surfaces with large organic molecules serving as promoters or modifiers of chemical reactions. We present a general overview of the apparatus as well as a description of the individual components and their interplay. The results of the test measurements involving the most important components are presented and discussed.

Fast-timing microchannel plate photodetectors: Design, fabrication, and characterization.

We report a detailed design, fabrication, and characterization of 6 × 6 cm2 fast timing photodetectors based on next-generation microchannel plates (MCPs). The whole assembly is made of low-cost borosilicate glass materials and hermetically sealed with a bialkali photocathode in a vacuum. The flexible photodetector design provides the potential of modifying individual components as well as the entire configuration to fit for different applications. A series of prototype MCP-photodetectors were fabricated following a step-by-step process including functionalization of glass capillary array through atomic layer deposition, MCP baking and scrubbing, photocathode deposition, and hermetic thermo-compression sealing. The prototype MCP-photodetectors exhibit electron gains well beyond 107 level with good relative uniformity. An excellent rise time of 439 ps, timing distribution root-mean-square at a single photoelectron mode of 105 ps, a timing resolution of 20 ps, and magnetic field tolerance up to 1.3 T were achieved for a photodetector with 10 µm pore size MCPs, comparing to that of 536 ps, 205 ps, 63 ps, and 0.7 T for the one with 20 µm pore size MCPs.

Large Area Picosecond Photodetector (LAPPDTM) - Pilot production and development status

Abstract We report performance results achieved for fully functional sealed Large Area Picosecond Photodetectors (LAPPD™) in tests performed at Incom Inc., as well as independent test results reported by our early adopters. The LAPPD is a microchannel plate (MCP) based large area picosecond photodetector, capable of imaging with single-photon sensitivity at high spatial and temporal resolutions in a hermetic package. The LAPPD has an active area of 350 square centimeters in an all-glass hermetic package with a fused silica window and bottom plate and sidewalls made of borosilicate float glass. Signals are generated by a bi-alkali Na 2 KSb photocathode and amplified with a stacked chevron pair of MCPs produced by applying resistive and emissive atomic layer deposition coatings to glass capillary array (GCA) substrates. Signals are collected on RF stripline anodes applied to the bottom plates which exit the detector via pin-free hermetic seals under the side walls. LAPPD test and performance results for product produced and delivered to early adopter customers during the first half of 2018 are reviewed. These results include electron gains ≥ 7.5 × 106 @ 850/950 V (entry/exit MCP), low dark noise rates (22 Cts/s/cm2 ), single photoelectron (PE) timing resolution of 64 picoseconds RMS, and single photoelectron spatial resolution along and across strips of 2.8 mm and 1.3 mm RMS respectively. Many of these devices also had very high QE photocathodes that were uniform over the full 195 mm × 195 mm window active area (LAPPD #15 QE% @ 365 nm Max/Avg/Min = 25.8/22.3 ± 3/15.7). An update is also provided of developments that enable capacitive signal coupling from the detector to application specific pads or stripline readout patterns deployed on printed circuit boards positioned beneath the tile, outside of the vacuum package. We conclude with examples of how sensors offering picosecond timing, in diverse applications can bring transformative change to detector technology and applications in future experiments.

Rapid detection of the presence of diffusion exchange

Diffusion exchange spectroscopy (DEXSY) provides a detailed picture of how fluids in different microenvironments communicate with one another but requires a large amount of data. For DEXSY MRI, a simple measure of apparent exchanging fractions may suffice to characterize and differentiate materials and tissues. Reparameterizing signal intensity from a PGSE–storage–PGSE experiment as a function of the sum, bs=b1+b2, and difference bd=b2-b1 of the diffusion encodings separates diffusion weighting from exchange weighting. Exchange leads to upward curvature along a slice of constant bs. Exchanging fractions can be measured rapidly by a finite difference approximation of the curvature using four data points. The method is generalized for non-steady-state and multi-site exchange. We apply the method to image exchanging fractions and calculate exchange rates of water diffusing across the bulk water interface of a glass capillary array.

A new recipe for preparing oxidized TiO2(1 1 0) surfaces: An STM study

Using high-resolution scanning tunneling microscopy (STM), we have studied the oxidation of rutile TiO2(1 1 0)–(1 × 1) surfaces with Had species at room temperature. We followed the evolution of various stable species as function of the O2 exposure, and the nature of the ultimately dominating species in the Ti troughs is described. When O2 saturation was accomplished using a glass-capillary array doser, we found that on-top O (Oot) adatoms are the predominant surface species. In contrast, when O2 was supplied via backfilling of the chamber the predominant surface species are tentatively assigned to terminal OH groups. We argue that unintended reactions with the chamber walls have a strong influence on the formed surface species, explaining scattered results in the literature. On the basis of our STM data we propose an alternative, easy way of preparing oxidized TiO2(1 1 0) surfaces with Oot adatoms (o-TiO2). It is certain that o-TiO2(1 1 0) surfaces prepared according to this recipe do not have any residual surface O vacancies. This contradicts the situation when oxidizing reduced TiO2(1 1 0) surfaces with O vacancies, where some O vacancies persist.

Grid-enhanced X-ray coded aperture microscopy with polycapillary optics

Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10–100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy.

A fully integrated microchip system for automated forensic short tandem repeat analysis.

We have successfully developed an integrated microsystem that combines two plastic microchips for DNA extraction and PCR amplification with a glass capillary array electrophoresis chip together in a compact control and detection instrument for automated forensic short tandem repeat (STR) analysis. DNA extraction followed by an "in situ PCR" was conducted in a single reaction chamber of the microchip based on a filter paper-based extraction methodology. PCR products were then mixed with sizing standards by an injection electrode and injected into the electrophoresis chip for four-color confocal fluorescence detection. The entire STR analysis can be completed in about two hours without any human intervention. Since the 15-plex STR system has a more stringent requirement for PCR efficiency, we optimized the structure of the plastic DNA extraction and amplification chip, in which the reaction chamber was formed by sandwiching a hollow structure layer with two blank cover layers, to reduce the adsorption of PCR reagents to the surfaces. In addition, PCR additives, bovine serum albumin, poly(ethylene glycol), and more magnesium chloride were included into the on-chip multiplex STR system. The limit-of-detection study demonstrated that our microsystem was able to produce full 15-plex STR profiles from 3.75 ng standard K562 DNA. Buccal swab and whole blood samples were also successfully typed by our system, validating the feasibility of performing rapid DNA typing in a "sample-in-answer-out" manner for on-site forensic human identification.

Glass capillary based microfluidic ELISA for rapid diagnostics.

Enzyme-linked immunosorbent assay (ELISA) is widely used in medical diagnostics and fundamental biological research due to its high specificity and reproducibility. However, the traditional 96-well-plate based ELISA still suffers from several notable drawbacks, such as long assay time (4-6 hours), burdensome procedures and large sample/reagent volumes (∼100 μl), which significantly limit traditional ELISA's applications in rapid clinical diagnosis and quasi-real-time prognosis of some fast-developing diseases. Here, we developed a user friendly glass capillary array based microfluidic ELISA device. Benefiting from the high surface-to-volume ratio of the capillary and the rapid chemiluminescent photo-imaging method with a commercial camera, our capillary based ELISA device significantly reduced the sample volume to 20 μL and shortened the total assay time to as short as 16 minutes (including detection time), which represent approximately 10-fold and 5-fold reduction in assay time and sample volume, respectively, in comparison with the traditional plate-based method. Furthermore, through the double exposure method, a nearly 10-fold increase in the detection dynamic range was achieved over the traditional well-based ELISA. Our device can be broadly used in rapid biochemical analysis for biomedicine and research/development laboratories.

Anisotropic phantom to calibrate high-q diffusion MRI methods

A silicon oil-filled glass capillary array is proposed as an anisotropic diffusion MRI phantom. Together with a computational/theoretical pipeline these provide a gold standard for calibrating and validating high-q diffusion MRI experiments. The phantom was used to test high angular resolution diffusion imaging (HARDI) and double pulsed-field gradient (d-PFG) MRI acquisition schemes. MRI-based predictions of microcapillary diameter using both acquisition schemes were compared with results from optical microscopy. This phantom design can be used for quality control and quality assurance purposes and for testing and validating proposed microstructure imaging experiments and the processing pipelines used to analyze them.

Microchannel plate fabrication using glass capillary arrays with Atomic Layer Deposition films for resistance and gain

AbstractMicrochannel plates (MCPs) have been used for many years in space flight instrumentation as fast, lightweight electron multipliers. A new MCP fabrication method combines a glass substrate composed of hollow glass capillary arrays with thin film coatings to provide the resistive and secondary electron emissive properties. Using this technique, the gain, resistance, and glass properties may be chosen independently. Large‐area MCPs are available at moderate cost. Secondary emission films of Al2O3 and MgO provide sustained high gain as charge is extracted from the MCP. Long lifetimes are possible, and a total extracted charge of 7 C/cm2 has been demonstrated. Background rates are low because the glass substrate has little radioactive potassium 40. Curved MCPs are easily fabricated with this technique to suit instrument symmetries, simplifying secondary electron steering and smoothing azimuthal efficiency.

Pilot production & commercialization of LAPPD™

We present a progress update on plans to establish pilot production and commercialization of Large Area (400cm2) Picosecond Photodetector (LAPPD™). Steps being taken to commercialize this MCP and LAPPD™ technology and begin tile pilot production are presented including (1) the manufacture of 203mm×203mm borosilicate glass capillary arrays (GCAs), (2) optimization of MCP performance and creation of an ALD coating facility to manufacture MCPs and (3) design, construction and commissioning of UHV tile integration and sealing facility to produce LAPPDs. Taken together these plans provide a “pathway toward commercialization”.

Application of a new-structure polycapillary x-ray optics in high pressure XAFS

New-structure polycapillary x-ray optics for high pressure x-ray absorption fine structure (XAFS) absorption spectroscopy using the diamond anvil cells (DAC) method are applied in synchrotron radiation analysis. The optics are composed of a solid glass fiber in the center and surrounded by a hollow glass capillary array. They can restrain the higher harmonic of incident synchrotron radiation and obtain smooth and clear XAFS spectra. At the biological macromolecule station in the Beijing Synchrotron Radiation Facility (BSRF), a method of aligning these optics was developed and the transmission efficiency for both fundamental and higher harmonic waves investigated. The XAFS spectra of topological insulator material of Bi2Se3 were obtained by combining the optics.

Nonparametric pore size distribution using d-PFG: Comparison to s-PFG and migration to MRI

Here we present the successful translation of a pore size distribution (PSD) estimation method from NMR to MRI. This approach is validated using a well-characterized MRI phantom consisting of stacked glass capillary arrays (GCA) having different diameters. By employing a double pulsed-field gradient (d-PFG) MRI sequence, this method overcomes several important theoretical and experimental limitations of previous single-PFG (s-PFG) based MRI methods by allowing the relative diffusion gradients’ direction to vary. This feature adds an essential second dimension in the parameters space, which can potentially improve the reliability and stability of the PSD estimation. To infer PSDs from the MRI data in each voxel an inverse linear problem is solved in conjunction with the multiple correlation function (MCF) framework, which can account for arbitrary experimental parameters (e.g., long diffusion pulses). This scheme makes no a priori assumptions about the functional form of the underlying PSD. Creative use of region of interest (ROI) analysis allows us to create different underlying PSDs using the same GCA MRI phantom. We show that an s-PFG experiment on the GCA phantom fails to accurately reconstruct the size distribution, thus demonstrating the superiority of the d-PFG experiment. In addition, signal simulations corrupted by different noise levels were used to generate continuous and complex PSDs, which were then successfully reconstructed. Finally, owing to the reduced q- or b- values required to measure microscopic PSDs via d-PFG MRI, this method will be better suited to biomedical and clinical applications, in which gradient strength of scanners is limited.

TU‐C‐12A‐07: Characterization of Longitudinal Reproducibility of Quantitative Diffusion Imaging Data Acquired with Four Different Protocols Using a Phantom

Purpose:To characterize and compare the longitudinal reproducibility of diffusion imaging data acquired with four different protocols using a phantom.Methods:The Diffusive Quantitative Imaging Phantom (DQIP) was constructed using fifteen cylindrical compartments within a larger compartment, filled with deionized water doped with CuSO4 and NaCl. The smaller compartments contained arrays of hexagonal or cylindrical glass capillaries of varying inner diameters, for differing restraint of water diffusion. The sensitivity of diffusion imaging metrics to signal‐to‐noise ratio (SNR) was probed by doping compartments with differing ratios of deuterium oxide to H2O. A cork phantom enclosure was constructed to increase thermal stability during scanning and a cork holder was made to reproduce scanner positioning. Four different protocols of DWI (diffusion weighted imaging) and DTI (Diffusion tensor imaging) imaging were assembled on a GE Excite HDx 3.0T MRI scanner to collect imaging data over 9‐10 days. Data was processed with in‐house software created in Matlab to obtain fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values.Results:All DTI and DWI sequences showed good longitudinal stability of mean FA and ADC values per compartment, exhibiting low standard deviation ∼9%. A t‐test was performed to compare mean FA values from the DTI clinical protocol to those of the DTI special protocol, indicating significantly different values in the majority of compartments. ANOVA performed on ADC values for all DTI and DWI sequences also showed significantly different values in a majority of compartments.Conclusion:This work has the potential for quantifying systemic variations between diffusion imaging sequences from different platforms. Characterization of DWI and DTI performance were done over four sequences with predictable results. This data suggests that the DQIP phantom may be a reliable method of monitoring day‐to‐day and scan‐to‐scan variation in diffusion imaging sequences from different platforms.Schott Glass North America and The Phantom Laboratory have donated materials and personnel time to this project.

Mapping average axon diameters in porcine spinal cord white matter and rat corpus callosum using d-PFG MRI

Knowledge of microstructural features of nerve fascicles, such as their axon diameter, is crucial for understanding normal function in the central and peripheral nervous systems as well as assessing changes due to pathologies. In this study double-pulsed field gradient (d-PFG) filtered MRI was used to map the average axon diameter (AAD) in porcine spinal cord, which was then compared to AADs measured with optical microscopy of the same specimen, as a way to further validate this new MRI method. A novel 3D d-PFG acquisition scheme was used to obtain AADs in each voxel of a coronal slice of rat brain corpus callosum. AAD measurements were also acquired using optical microscopy performed on histological sections and validated using a glass capillary array phantom.

An Atomic Layer Deposition Method to Fabricate Economical and Robust Large Area Microchannel Plates for Photodetectors

Abstract We demonstrate an economical and robust route to fabricate large-area microchannel plate (MCP) detectors which will open new opportunities in larger area MCP-based detector technologies. Using our newly developed bottom-up process flow, we have fabricated large area MCPs (8 x 8). We used Atomic Layer Deposition (ALD), a powerful and precise thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE) properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD allows atomic level control over the thickness and composition of resistive and secondary electron emission (SEE) layers that can be deposited conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD processes for the resistive coatings and SEE layers to give us precise control over the resistance in the target range for MCPs (106-109 Ω) and SEE coefficient (up to 8). The MCPs are tested in stacks of one or two plates and exhibit gains as high as 107 for a pair of MCPs. This approach allows the functionalization of microporous, insulating substrates to produce MCPs with high gain and low noise. These capabilities allow separation of the substrate material properties from the amplification properties. We studied the various MCP parameters such as gain, background counts, and resistance as a function of the ALD process parameters. Here we describe a complete process flow to produce fully functionalized working large area MCPs.