Planar Format Research Articles

COMPUTATIONAL VISION IN UV-MAPPING OF TEXTURED MESHES COMING FROM PHOTOGRAMMETRIC RECOVERY: UNWRAPPING FRESCOED VAULTS

Abstract. Sometimes it is difficult to represent “on paper" the existing reality of architectonic elements, depending on the complexity of his geometry, but not only in cases with complex geometries: non-relief surfaces, can need a “special planar format” for its graphical representation. Nowadays, there are a lot of methods to obtain tridimensional recovery of our Cultural Heritage with different ranges of the relationship accuracy / costs, even getting high accuracy using “low-cost” recovery methods as digital photogrammetry, which allow us easily to obtain a graphical representation “on paper”: ortho-images of different points of view. This can be useful for many purposes but, for others, an orthographic projection is not really very interesting. In non-site restoration tasks of frescoed vaults, a “planar format” representation in needed to see in true magnitude the paintings represented on the intrados vault, because of the general methodology used: gluing the fresco on a fabric, removing the fresco-fabric from the support, moving to laboratory, removing the fresco from the fabric, restoring the fresco, gluing back the restored fresco on another fabric, laying the restored fresco on the original location and removing the fabric. Because of this, many times, an unfolded model is needed, in a similar way a cylinder or cone can be unfolded, but in this case with a texture included: UV unwrapping. Unfold and fold-back processes, can be especially interesting in restoration field of frescoed vaults and domes at: chromatic recovery of paintings, reconstruction of partially missed geometries, transference of paintings on surfaces, etc.

COMPUTATIONAL VISION IN UV-MAPPING OF TEXTURED MESHES COMING FROM PHOTOGRAMMETRIC RECOVERY: UNWRAPPING FRESCOED VAULTS

Sometimes it is difficult to represent “on paper" the existing reality of architectonic elements, depending on the complexity of his geometry, but not only in cases with complex geometries: non-relief surfaces, can need a “special planar format” for its graphical representation. <br><br> Nowadays, there are a lot of methods to obtain tridimensional recovery of our Cultural Heritage with different ranges of the relationship accuracy / costs, even getting high accuracy using “low-cost” recovery methods as digital photogrammetry, which allow us easily to obtain a graphical representation “on paper”: ortho-images of different points of view. This can be useful for many purposes but, for others, an orthographic projection is not really very interesting. <br><br> In non-site restoration tasks of frescoed vaults, a “planar format” representation in needed to see in true magnitude the paintings represented on the intrados vault, because of the general methodology used: gluing the fresco on a fabric, removing the fresco-fabric from the support, moving to laboratory, removing the fresco from the fabric, restoring the fresco, gluing back the restored fresco on another fabric, laying the restored fresco on the original location and removing the fabric. Because of this, many times, an unfolded model is needed, in a similar way a cylinder or cone can be unfolded, but in this case with a texture included: UV unwrapping. <br><br> Unfold and fold-back processes, can be especially interesting in restoration field of frescoed vaults and domes at: chromatic recovery of paintings, reconstruction of partially missed geometries, transference of paintings on surfaces, etc.

2-Dimensional Supercapacitor Wires to Overcome Intrinsic Low Energy Density

Although a large number of reports on 2D flexible and stretchable energy storage devices have emerged within the past decade, 1D structure systems such as wires for higher flexibility, bio-compatibility and wearability have been desired for broader application of electronics. As a result of these requirements, wire-shaped devices among the cutting edge technologies in energy storage field are taking center stage for application to postmodern electronics and various fields such as fashion and culture. In view of mechanics, plane structures in 2D essentially have a unidirectional folding characteristics. On the other hand, wires with 1D structure have an omnidirectional serpentine structure in the other axes. In contrast to 2D planar formats, it is much easier for wire types to be integrated into more sophisticated structures such as woven textiles that can be used in our daily life. Although wire systems have a large structural potential, some fundamental obstacles hinder the use of wire-type energy storage. Electrochemical performances of wires are still underneath those of 2D plane cells. Many researchers have made efforts to overcome these barriers of wire-type energy storage devices. Most of them suggests ways to shape electrodes into cylindrical wires and a choice of material to maximize the performance as high as possible. In this study, however, we did not stick to using superb materials or constructing a cylinder, but theoretically analysed the origin of undefeatable charge-storage property of 2D plane over 1D wire. Based on this analysis we verified that a difference between wire-type and conventional planar supercapacitors induced the fundamental limits of wire-type supercapacitors. This limit is termed “energy lag effect.” With these derived information, we have first proposed the simultaneous incorporation of favorable electrochemical performance of 2D system and high flexibility of 1D system into solely one device. To exclude the identified limits, we designed a supercapacitor thread in unique structure that completely differs from conventional wire-type energy storage systems. The supercapacitor thread was designed as a dual plane-helix structure and proved not to show energy lag effects, experimentally or analytically.

Bead-based microarray immunoassay for lung cancer biomarkers using quantum dots as labels

In this study, we developed a multiplex immunoassay system that combines the suspension and planar microarray formats within a single layer of polydimethylsiloxane (PDMS) using soft lithography technology. The suspension format was based on the target proteins forming a sandwich structure between the magnetic beads and the quantum dot (QD) probes through specific antibody–antigen interactions. The planar microarray format was produced by fabricating an array of micro-wells in PDMS. Each micro-well was designed to trap a single microbead and eventually generated a microbead array within the PDMS chamber. The resultant bead-based on-chip assay could be used for simultaneously detecting three lung cancer biomarkers—carcinoembryonic antigen (CEA), fragments of cytokeratin 19 (CYFRA21-1) and neuron-specific enolase (NSE)—in 10μl of human serum, with a wide linear dynamic range (1.03–111ng/mL for CEA and CYFRA21-1; 9.26–1000ng/ml for NSE) and a low detection limit (CEA: 0.19ng/ml; CYFRA21-1: 0.97ng/ml; NSE: 0.37ng/ml; S/N=3). Our micro-well chip does not require complex e-beam lithography or the reactive ion etching process as with existing micro-well systems, which rely on expensive focused ion beam (FIB) milling or optical fiber bundles. Furthermore, the current approach is easy to operate without extra driving equipment such as pumps, and can make parallel detection for multiplexing with rapid binding kinetics, small reagent consumption and low cost. This work has demonstrated the importance of the successful application of on-chip multiplexing sandwich assays for the detection of biomarker proteins.

Structural Mimetic Silk Fiber-Reinforced Composite Scaffolds Using Multi-Angle Fibers.

The fabrication of structural mimetic scaffolds reinforced with multi-angle silk fibers is described. Degummed silk fibers with a parallel arrangement of the fibers in a planar format were overlapped with successive layers organized at 0°, 30°, 60° and 90°, respectively. The overlapped silk fiber layers were coated with silk solution (6 wt%) containing sodium dodecyl sulfate (SDS). The morphology, mechanical properties, structure and biocompatibility of the scaffolds were investigated. The mechanical properties of the scaffolds (tensile and burst) were characterized based on the angles of the fibers. Layers with an overlapping angle at 30° exhibited better mechanical performance (18 MPa) than the other groups. The results of Fourier Transform (FT) IR Spectroscopy (FT-IR) and X-ray Differentiation (XRD) analyses indicated that the presence of degummed silk fibers with different angles did not significantly impact secondary structure or crystallization of the fiber reinforced scaffolds. The attachment and growth of a human fibroblast cell line (HS-865-SK) on the reinforced scaffolds supported good cell compatibility. These new scaffolds have potential applications in tissue repairs where superior mechanical strength and cell compatibility are important.

Microfluidic-based multiplex immunoassay system integrated with an array of QD-encoded microbeads

Here, we developed a multiplex immunoassay platform within microfluidic devices that combines suspension and the planar microarray format. For the suspension microarray format, QD-embedded polymeric microbeads with an average diameter of 24μm were prepared using the Shirasu Porous Glass (SPG) membrane emulsification technique. To furnish the microbeads with resolvable spectral codes, QDs with two different colors (450nm for blue and 520nm for green) were used and different spectral codes were obtained by changing the ratio of emission intensity of the two different QDs within the microbeads. The surfaces of the QD-encoded microbeads were then functionalized with probe antibodies for immunoassays. The planar microarray format was achieved by an array of microholes fabricated in PDMS. Each microhole was designed to trap a single microbead and eventually generated a microbeads array within the microfluidic system. The feasibility of the microbead array within microfluidic devices for use in a multiplex immunoassay was demonstrated by immunobinding assays between IgG and anti-IgG and/or between IgM and anti-IgM. Furthermore, the resultant microbead-based on-chip assay could be used for a sandwich assay to detect prostate-specific antigen (PSA), a model cancer marker, with a detection limit of 1ng/mL. The combination of suspension and the planar microarray format enabled the spatial location of individual microbeads within physically separated regions and thus facilitated the simultaneous determination of different targets that interacted with the corresponding microbeads.

Integration of monolithic porous polymer with droplet-based microfluidics on a chip for nano/picoliter volume sample analysis.

In this paper, a porous polymer nanostructure has been integrated with droplet-based microfluidics in a single planar format. Monolithic porous polymer (MPP) was formed selectively within a microfluidic channel. The resulting analyte bands were sequentially comartmentalised into droplets. This device reduces band broadening and the effects of post-column dead volume by the combination of the two techniques. Moreover it offers the precise control of nano/picoliter volume samples.

Compliant, Heterogeneously Integrated GaAs Micro-VCSELs towards Wearable and Implantable Integrated Optoelectronics Platforms

Vertical cavity surface emitting lasers (VCSELs) represent a ubiquitous light source with unique performance characteristics that excel for edge-emitting lasers or light-emitting diodes. VCSELs are available, however, mostly on growth wafers in rigid, planar formats over restricted areas, thereby frustrating their use for applications that benefit greatly from unconventional design options including large-scale, programmable assemblies on unusual substrates, hybrid integration with dissimilar materials and devices, or mechanically compliant constructions. Here, materials design and fabrication strategies are presented to overcome these limitations of conventional VCSELs and create new application opportunities that are unavailable with existing technologies. Specialized epitaxial design and fabrication processes, together with printing-based integration methods, enable defect-free release of ultrathin, microscale VCSELs and their device-level implementation on non-native substrates in a scalable, cost-effective fashion. Demonstrations of large-scale, addressable arrays of VCSELs on plastics for flexible near-infrared laser displays, and heterogeneous assemblies with silicon-based electronics to form integrated optoelectronic sensors, illustrate unique capabilities.

A Highly Stretchable, Fiber‐Shaped Supercapacitor

Flexible and portable devices are a mainstream direction in modern electronics and related multidisciplinary fields. To this end, they are generally required to be stretchable to satisfy various substrates. As a result, stretchable devices, such as electrochemical supercapacitors, lithium-ion batteries, organic solar cells, organic light-emitting diodes, field-effect transistors, and artificial skin sensors have been widely studied. However, these stretchable devices are made in a conventional planar format that has largely hindered their development. For the portable applications, the devices need to be lightweight and small, though it is difficult for them to be made into efficient microdevices. In particular, it is challenging or even impossible for them to be used in electronic circuits and textiles that are urgently required also in a wide variety of other fields, such as microelectronic applications. Recently, some attempts have been made to fabricate wire-shaped microdevices, such as electrochemical supercapacitors. They have been generally produced by twisting two fiber electrodes with electrolytes coated on the surface. Several examples have been also successfully shown to make fiber-shaped supercapacitors with a coaxial structure. Compared with their planar counterparts, the wire or fiber shape enables promising advantages such as being lightweight and woven into textiles. Although the wire and fiber-shaped supercapacitors are also flexible with high electrochemical performance, they are not stretchable, which is critically important for many applications. For instance, the resulting electronic textiles could easily break during the use if they were not stretchable. To the best of our knowledge, herein we have, for the first time, developed a novel family of highly stretchable, fibershaped high-performance supercapacitors. Aligned carbon nanotube (CNT) sheets that are sequentially wrapped on an elastic fiber serve as two electrodes. The use of aligned CNT sheets offers combined remarkable properties including high flexibility, tensile strength, electrical conductivity, and mechanical and thermal stability. As a result, the fibershaped supercapacitor maintains a high specific capacitance of approximately 18 F/g after stretch by 75% for 100 cycles. Spinnable CNT arrays were first synthesized by chemical vapor deposition. A scanning electron microscopy (SEM) image of the array with height of 230 mm is shown in the Supporting Information, Figure S1, and the CNT shows a multi-walled structure with diameter of about 10 nm (Supporting Information, Figure S2). Aligned CNT sheets could be then continuously drawn from the array and easily attached to various substrates. Elastic fibers were used herein to offer the stretchability in the resulting supercapactiors, and rubber fibers have been mainly studied as a demonstration. For a typical fabrication on the fiber-shaped supercapacitor (Figure 1), a rubber fiber was first coated with a thin layer of

A method for detecting forward scattering signals on-chip with a photonic-microfluidic integrated device.

A photonic integrated microfluidic device is demonstrated to perform optical excitation and forward scatter collection all on-chip in a planar format. Integrated on-chip optics formed a tailored beam geometry for optimal excitation of particles while a special design modification allowed for on-chip forward collection with the beam shaping capabilities. A notch was placed in the lens system that caused a dark spot on the facet of a collection waveguide while not affecting the beam geometry at the point of interrogation. The modified device with the ability to form a 10 μm beam geometry was demonstrated to detect the forward scatter from blank 5 μm diameter polystyrene beads. Free-space collection of side scatter signals was performed simultaneously with the on-chip collection and the designs demonstrated and enhanced SNR while the reliability of detection was determined to be appropriate for many applications. Excellent performance was confirmed via a false positive rate of 0.4%, a missed events rate of 6.8%, and a coincident rate of 96.3% as determined between simultaneously performed free-space and on-chip detection schemes.

Planar radionuclide angiography with a dedicated cardiac SPECT camera

BackgroundWe compared a dedicated cardiac camera with a traditional system for left ventricular (LV) functional measurements using gated blood-pool imaging. Methods24-frame gated planar images were obtained from 48 patients in an LAO orientation for 6M counts/view on a standard gamma camera. Immediately thereafter, 24-frame ECG-gated data were obtained for 8 minutes on a dedicated cardiac SPECT camera. The gated SPECT image volumes were iteratively reconstructed and then transferred offline. In-house software was used to reproject the images into a 24-frame gated planar format. Both the original and the reprojected gated planar datasets were analyzed using semiautomated software to determine ejection fraction (EF), ventricular volume (end diastolic volume, EDV), peak ejection rate (PER), and peak filling rate (PFR). ResultsThe difference in EF values averaged 0.4% ± 4.4%. The correlation in EF was r ≥ 0.94 (P < .01) with a linear regression slope of 0.98. Correlation of the EDV was r ≥ 0.86 (P < .01), but the volumes from the dedicated cardiac camera were smaller (linear regression slope was 0.6). Correlation of PFR and PER were r = 0.91 and r ≥ 0.83, respectively (P < .01 for both). ConclusionsReprojection of 24-frame gated blood-pool SPECT images is an effective means of obtaining LV functional measurements with a dedicated cardiac SPECT camera using standard 2D-planar analysis tools.

Recent progress in InSb based quantum detectors in Israel

InSb is a III–V binary semiconductor material with a bandgap wavelength of 5.4μm at 77K, well matched to the 3–5μm MWIR atmospheric transmission window. When configured as a Focal Plane Array (FPA) detector, InSb photodiodes offer a large quantum efficiency, combined with excellent uniformity and high pixel operability. As such, InSb arrays exhibit good scalability and are an excellent choice for large format FPAs at a reasonable cost. The dark current is caused by Generation–Recombination (G–R) centres in the diode depletion region, and this leads to a typical operating temperature of ∼80K in detectors with a planar implanted p–n junction. Over the last 15years SCD has developed and manufactured a number of different 2-dimensional planar FPA formats, with pitches in the range of 15–30μm.In recent years a new epi-InSb technology has been developed at SCD, in which the G–R contribution to the dark current is reduced. This enables InSb detector operation at 95–100K, with equivalent performance to standard InSb at 80K. In addition, using a new patented XBnn device architecture in which the G–R current is totally suppressed, epitaxial InAsSb detectors have been developed with a bandgap wavelength of 4.2μm, which can operate in the 150–170K range.In this short review of the past two decades, a number of key achievements in SCD’s InSb based detector development program are described. These include High Operating Temperature (HOT) epi-InSb FPAs, large format megapixel FPAs with high functionality using a digital Read Out Integrated Circuit (ROIC), and ultra low Size, Weight and Power (SWaP) FPAs based on the HOT XBnn architecture.

Macromolecular binding and kinetic analysis with optically sectioned planar format assays

Real-time analysis of macromolecular interactions and competitive binding of ligands to receptors on surfaces are not typically performed using fluorescence intensity methods due to background interference from solution fluorescence. Separation-free optically sectioned planar format assays (OSPFAs) with confocal detection remove this problem. We report OSPFAs for indicator displacement and kinetic assessment of binding. A commercial androgen receptor binding domain indicator displacement assay adapted as an OSPFA yielded an IC(50) of 6.5 nM for testosterone with Z' = 0.77. These measured IC(50) and Z' values are in ranges suitable for drug screening applications with Z' > 0.5 indicating good to excellent screenability. An OSPFA was applied to study the rate of antibody binding to a sandwich immunoassay on a planar surface. Langmuir fits provided forward rate constants in the range 2 × 10(3) M(-1) s(-1) to 6 × 10(4) M(-1) s(-1) and reverse constants 1 × 10(-4) s(-1) to 4 × 10(-3) s(-1) which cover a useful range for characterising probe-target interactions. This work demonstrates the suitability of OSPFAs for investigating kinetics and binding interactions using fluorescence under wash-free conditions. OSPFAs are an alternative to other separation-free methods such as acoustic, surface plasmon resonance, ellipsometry, fluorescence polarisation and other related methods. OSPFAs should make practical dynamic binding studies for small and large molecules including cases where the reaction under investigation results in no appreciable mass change on a surface.

Overcoming the Deficiency of Singular Detection by Antibody Arrays in Cancer Biomarker Discovery

Since cancer is a heterogeneous disease, it is unlikely that a single biomarker will detect all cancers of a particular organ with high specificity and sensitivity. Thus, detection of expression of multiple proteins is essential to unraveling the mechanisms and effects of carcinogenesis. Antibody arrays have been developed to meet this growing demand. The ability to simultaneously measure the expression profiling of multi-protein markers will provide a powerful platform for identification of new cancer biomarkers. In this review, we will discuss the planar format of antibody array technology, its suitability and challenges for cancer biomarker discovery, and examples of its applications for biomarker discovery and validation in a wide variety of human cancers

Kinetic Analysis and Binding Studies of Proteins Bound to Planar Surfaces with CLSM

A number of techniques, such as surface plasmon resonance, are available to monitor surface bound molecular interactions. Detection of fluorophore binding to surface immobilized proteins may be conveniently detected in a separation-free method with confocal laser scanning microscopy (CLSM). We will present kinetic and equilibrium based studies including sandwich immunoassays and ligand-receptor displacement interactions on single planar surfaces. Kinetic analysis of antibody binding using fluorescein and quantum dots as reporters was able to resolve two components. QDs were found to bind slower, an effect ascribed to the greater mass of a typical QD. Ligand receptor studies were carried out on the androgen receptor binding domain in which a fluorescently labelled molecule was displaced by testosterone. This yielded an IC50 of 6.4 nM and a Z′ factor of 0.77. By replacing single subtrates with a multilayer structure created withe 30 μm thick substrates, a high density array of immunosorbent assays was created within a stratified medium. Model IgG based immunoassays were stacked into arrays over 5 layers with quantitative results obtained via layer dependent calibrations. As the number of layers increased there was a decrease in fluorescent intensity and a concomitant broadening of the axial response. Then the microcontact printing method was chosen to print antigens on modified mica substrates to carry out indirect immunoassays with QD-conjugated antibodies. Stacked layers of mica with patterned immunoassays were scanned with CLSM and 3D image was produced. While much of the capabilities of the planar format confocally read assay are available through other methods, the wide deployment of confocal microscopes and related ELISA techniques makes this an attractive approach to binding studies and the time dependent approach to equilibrium.

Sol–gel-derived photonic structures: fabrication, assessment, and application

Sol–gel is a handy, very flexible, and cheap method to fabricate, study, and apply innovative photonic structures. The possibility of starting from molecular precursors and elementary building blocks permits to tailor structures at the molecular level and to create new materials with enhanced performances. Of specific interest for the study of important physical effects as well as for application in light management are confined structures on the nano-micro scale as photonic crystal and planar waveguides. Activation by luminescent species and in particular by rare earth ions allows results in the integrated optics area covering application in sensing, biomedical diagnostic, telecommunication, lightning, and photon management. The present review is focused on some recent results obtained by the authors in Sol–gel photonics. The first part presents colloidal structures including single nano-micro spheres and photonic crystal structures. The second part of the review deals with amorphous and transparent glass–ceramic employed for the fabrication of confined structures in planar format. Some specific application are also reported to highlight the role of sol gel photonics in the development of high performance optical sensors, waveguide lasers, and nanostructured materials.

Rare earth–activated glass-ceramic in planar format

Rare earth-activated glass-ceramic waveguides constitute a potential significant system to behave as an effective optical medium for light propagation and luminescence enhancement. We present a review on fabrication and optical, structural, and spectroscopic characterization of some kind of rare earth activated oxide glass-ceramic waveguides, obtained by sol-gel route with both bottom-up and top-down approaches, and fluoride glass-ceramic waveguides fabricated by physical vapor deposition.

Ultrasensitive Microarray Detection of Short RNA Sequences with Enzymatically Modified Nanoparticles and Surface Plasmon Resonance Imaging Measurements

A novel multiplexed method for short RNA detection that employs an enzymatic capture reaction onto DNA-modified silica nanoparticles (SiNPs) followed by nanoparticle-enhanced surface plasmon resonance imaging (SPRI) is demonstrated. SiNPs functionalized with 5'-phosphorylated single stranded DNA (ssDNA) are used with T4 RNA ligase to capture various short 20-24 base single-stranded RNA (ssRNA) oligonucleotides from a target solution. The ssRNA-modified SiNPs are collected from the target solution, specifically adsorbed onto a cDNA microarray and then detected with SPRI. The use of DNA-modified SiNPs to capture ssRNA for profiling has several advantages as compared to a planar SPRI surface bioaffinity adsorption format: (i) the target solution is exposed to a larger total surface area for the RNA ligation reaction; (ii) the SiNPs enhance the diffusion rate of the ssRNA to the surface; (iii) the SiNPs can be collected, washed, and preconcentrated prior to detection; and (iv) the ssRNA-modified SiNPs give an enhanced SPRI signal upon hybridization adsorption to the microarray. Our initial measurements demonstrate that this detection method can be used to detect multiple ssRNA sequences at concentrations as low as 100 fM in 500 μL.

An Evaluation of the Conductivity Profile in the Somatosensory Barrel Cortex of Wistar Rats

Microelectrode arrays used to record local field potentials from the brain are being built with increasingly more spatial resolution, ranging from the initially developed laminar arrays to those with planar and three-dimensional (3D) formats. In parallel with such development in recording techniques, current source density (CSD) analyses have recently been expanded up to the continuous-3D form. Unfortunately, the effect of the conductivity profile on the CSD analysis performed with contemporary microelectrode arrays has not yet been evaluated and most of the studies assumed it was homogeneous and isotropic. In this study, we measured the conductivity profile in the somatosensory barrel cortex of Wistar rats. To that end, we combined multisite electrophysiological data recorded with a homemade assembly of silicon-based probes and a nonlinear least-squares algorithm that implicitly assumed that the cerebral cortex of rodents could be locally approximated as a layered anisotropic spherical volume conductor. The eccentricity of the six cortical layers in the somatosensory barrel cortex was evaluated from postmortem histological images. We provided evidence for the local spherical character of the entire barrels field, with concentric cortical layers. We found significant laminar dependencies in the conductivity values with radial/tangential anisotropies. These results were in agreement with the layer-dependent orientations of myelinated axons, but hardly related to densities of cells. Finally, we demonstrated through simulations that ignoring the real conductivity profile in the somatosensory barrel cortex of rats caused considerable errors in the CSD reconstruction, with pronounced effects on the continuous-3D form and charge-unbalanced CSD. We concluded that the conductivity profile must be included in future developments of CSD analysis, especially for rodents.

Ion Transport in Nanofluidic Funnels

We report fabrication of nanofluidic channels with asymmetric features (e.g., funnels) that were cast in high modulus poly(dimethylsiloxane) and had well-defined geometries and dimensions. Masters used to cast the funnels were written in the negative tone resist SU-8 by electron beam lithography. Replicated funnels had taper angles of 5, 10, and 20 degrees and were 80 nm wide at the tip, 1 microm wide at the base, and 120 nm deep. The planar format permitted easy coupling of the funnels to microfluidic channels and simultaneous electrical and optical characterization of ion transport. All three designs rectified ion current, and the 5 degrees funnel exhibited the highest rectification ratio. Fluorescence measurements at the funnel base showed that an anionic probe was enriched and depleted in the high and low conductance states, respectively.