Micropattern Arrays Research Articles

Dynamic Profiling of Antitumor Activity of CAR T Cells Using Micropatterned Tumor Arrays.

Cancer immunotherapy based on the engineering of chimeric antigen receptors (CAR) on T cells has emerged as one of the most promising new therapies for patients with B‐cell malignancies. Preclinical assessments of essential CAR T cell functions such as trafficking and cytotoxicity are critical for accelerating the development of highly effective therapeutic candidates. However, current tools for evaluating CAR‐T functions lack sufficient precision. Here, a micropatterned tumor array (MiTA) is described that enables detailed and dynamic characterization of CAR T cell trafficking toward tumor‐cell islands and subsequent killing of tumor cells. It is shown that CAR T cells often merge into large clusters that envelop and kill the tumor cells with high efficiency. Significant differences are also measured between CAR T cells from different donors and between various CAR T cell constructs. Overall, the assay allows for multifaceted, dynamic, high‐content evaluation of CAR T trafficking, clustering, and killing and could eventually become a useful tool for immune‐oncology research and preclinical assessments of cell‐based immunotherapies.

Fabrication of Different Micro Patterned Arrays by Through Mask Electrochemical Micromachining

Patterned microstructures are among the basic micro features that are indispensable in improving the tribological performance and dependability of various mechanical components especially Micro-Electro-Mechanical Systems (MEMS). Through Mask Electrochemical Micromachining (TMEMM) is a feasible process for fabricating micro-patterned arrays with controlled dimension, location and density by maintaining suitable surface texture. In this paper, appropriate machining parameters along with optimal electrolyte combination have been utilized for achieving patterned arrays in the form of micro-dimples and micro-square features. Low aspect ratio mask made of a negative PR (AZ 4903) is being introduced during TMEMM due to its low cost, availability and chemical resistance. Pattern of micro-holes with an average diameter of 65μm as well as micro-squares with a side length of 65μm imprinted on the mask are being replicated over SS304 substrate with substantial repeatability. The influence of two major Electrochemical Micromachining (EMM) parameters viz. duty cycle and machining time are investigated on the machining accuracy and surface properties of the micro-dimples generated with mask of lean thicknesses. Circular micro-dimples with an undercut of 29.15μm, depth 44.10μm and Ra 0.091μm and square micro-dimples possessing 32.63μm undercut, 40.24μm depth and 0.081μm Ra have been successfully fabricated on SS304 by this process of TMEMM.

Localization of blue phase liquid crystal with ordered crystallographic direction and well-defined micro-patterning

The construction of uniform orientation of crystallographic direction of blue phase is of great importance for its practical applications and the scientific research of multi-dimensional controllable growth of soft matter. With the consideration of the weak thermal stability of blue phase, the uniform lattice orientation of blue phase is combined with localized polymer-stabilization in this work. So the relatively stable fabrication of micro-patterns for blue phase can be realized, and it is promising for researchers to prepare brand new photonic devices. To the best of our knowledge, the relevant reports are rather rare, and the successful implementation of the above ideas is full of difficulties according to current conditions. In this paper, the uniform, patterned and stable orientation of crystallographic direction of blue phase is achieved by using the aforementioned integrated method. Here in this work, facile rubbing alignment is used as the primary way to realize the uniform lattice orientation. Meanwhile, the polymer-stabilization, as an effective technological way, is used to stabilize the frustrated topological structure of aligned blue phase for a better stability and its application perspective. Furthermore, we construct the well-defined micro-patterned blue phase array including one-dimensional and two-dimensional pattern in virtue of facile and effective localized exposure. Simultaneously, the stability of such a micro-pattern under external field is also investigated to evaluate the validity of stabilized superstructure and characteristic behavior of unstable region. As a result, the micro-patterned blue phase array keeps good state even under the adequate exposure to high voltage. Finally, the potential photonic application is explored based on the above micro-patterns which exhibit good optical diffraction effects in the experiment that follows. In conclusion, it really provides a feasible route for achieving stable control about orientation of soft matter, like liquid crystal, and fabricating field-stable and periodic superstructure. Such a research will speed up the development of blue phase liquid crystal in crystallography, electronics, and photonics.

Growing micropatterned CNT arrays on aluminum substrates using hot-filament CVD process

Attempts to grow carbon nanotubes directly on to aluminum (Al) substrates have had limited success, primarily due to its relatively low melting point of 660°C. In this work, we have successfully synthesized vertically aligned CNTs (VACNTs) in a planar configuration (48µm tall) as well as, for the first time, a micropatterned array with 36µm tall CNTs on Al substrates. This was achieved by combining conventional microfabrication steps for patterning an array and a catalyst-assisted hot-filament CVD process with methane as carbon source gas for CNT synthesis. Such substrates can provide highly conductive and high specific surface area host materials for cathodes in lithium ion batteries and supercapacitors. We have demonstrated a >10× increase in surface area available for coating cathode nanoparticles in the 3D micropatterned CNT array, as compared to the planar configuration.

Effects of friction reduction of micro-patterned array of rough slider bearing

Complex micro-scale patterns have attracted interest because of the functionality that can be created using this type of patterning. This study evaluates the frictional reduction effects of various micro patterns on a slider bearing surface which is operating under mixed lubrication. Due to the rapid growth of contact area under mixed lubrication, it has become important to study the phenomenon of asperity contact in bearings with a heavy load. New analysis using the modified Reynolds equation with both the average flow model and the contact model of asperities is conducted for the rough slider bearing. A numerical analysis is performed to determine the effects of surface roughness on a lubricated bearing. Several dented patterns such as, dot pattern, dashed line patterns are used to evaluate frictional reduction effects. To verify the analytical results, friction test for the micro-patterned samples are performed. From comparing the frictional reduction effects of patterned arrays, the design of them can control the frictional loss of bearings. Our results showed that the design of pattern array on the bearing surface was important to the friction reduction of bearings. To reduce frictional loss, the longitudinal direction of them was better than the transverse direction.

Template-Synthesis of Conjugated Poly(3-Hexylselenophene) (P3HS) Nanofibers Using Femtosecond Laser Machined Fused Silica Templates

Abstract:We report on the preparation of conjugated polymer nanofibers via template-synthesis. A femtosecond laser machined fused silica template, with a micro-patterned array of high-aspect ratio surface nanopores, was first spin-coated with a polyvinyl alcohol (PVA) solution to form a water-soluble release layer. The PVA-lined template was then coated with a conjugated poly(3-hexylselenophene) (P3HS) – solvent solution. The solvent was allowed to dissipate, and the resulting {template / PVA liner / conjugated P3HS film} stack was then submerged in water to dissolve the PVA and release the conjugated polymer film from the template. The resulting conjugated polymer film exhibits an array of micro-patterned polymer nanofibers that constitute a negative replica of the PVA-lined template. The nanofibers come arranged in a vertical architecture that spans over the surface of the supporting film.

Abstract A54: Extracellular matrix geometry and 3D spatial confinement trigger diverse mechanisms of primary human glioblastoma cell migration

Abstract The ability to diffusely infiltrate as single cells through the highly confined extracellular spaces of the brain parenchyma and along blood vessels is a pathological hallmark of Glioblastoma Multiforme (GBM), which makes these tumors surgically incurable. The fact that GBM cells are capable of moving through diverse brain microenvironments raises the possibility that GBM cells may possess multiple mechanisms for invasion. At present, little is known about how GBM cells gain traction and generate sufficient contractile forces to overcome the mechanical challenge of migrating through the confined interstitial spaces of the brain. The purpose of this study is to gain cellular, biochemical and biophysical insights into GBM migration. To accomplish this we generated 1-D micro-patterned arrays that approximate the topography of brain microvasculature and microfluidic devices that approximate brain interstitial spaces. High-resolution 3D time lapse imaging is then used to track actin, myosin-II and alpha-tubulin dynamics during cell migration. We found that the geometry of micro-patterned laminin lanes in the absence of chemotactic, hapatotactic or durotactic gradients, is sufficient to trigger sustained (integrin) adhesion-dependent migration that is driven by actin polymerization at the leading edge and supported by acto-myosin-II cable-like structures that extend along the ventral and lateral edges of spindle shaped cells. A similar pattern of adhesion-dependent (mesenchymal) migration was seen in 3D channels with aspect ratio (15x15um) larger than the cell. In confined (5x5um) channels, GBM cells adopted interchangeable modes of migration, waxing between blebbing and mesenchyal migration (approximately 50:50). Blebbing migration was characterized by acto-myosin-II cable-like structures that extended the length of the cell along both ventral and dorsal surfaces. In contrast, mesenchymal phase migration was characterized by a cytoskeleton organization pattern that resembled 1-D migration. Exposure of cells in confined channels to actin inhibitors (latrunculin B and CK-666) caused the cells to adopt a blebbing predominant mode of migration, while myosin-II inhibitor (blebbistatin) induced a mesenchymal predominant pattern. While neither class of inhibitors blocked migration as a single agent, the combination produced cell arrest. GBM cells were also able to migrate through confined channels in the absence of any ECM coating by adopting a blebbing exclusive pattern of migration. This observation raises the possibility that in the absence of integrin signaling, GBM cells can use hydrostatic pressure to gain traction in confined spaces. Taken together these results suggest that GBM can interchangeably adopt adhesion dependent and independent modes of migration as they encounter different sized ECM topography and variable 3-D confinement. Citation Format: James O. Nyagilo, Sara Picirrillo, Yuxiao Sun, Loan T. Bui, Nanda Regmi, Jamie L. Wright, Donald Thevalingam, Armin Soltan Zadi, Young-tae Kim, Charles Choung, Digant P. Dave, Robert Bachoo. Extracellular matrix geometry and 3D spatial confinement trigger diverse mechanisms of primary human glioblastoma cell migration. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A54.

Effect of Current Collector and Pyrolysis Temperature on the Electrochemical Performance of Photoresist Derived Carbon Films

SU-8, an epoxy based negative photoresist has been demonstrated as a potential precursor to fabricate thin films and three-dimensional micropatterned arrays in glassy carbon. However, the use of silicon wafer as a substrate cum collector limits their use in real battery devices. In accordance with the commercial lithium ion battery architecture and also owing to enhanced conductivity, we have successfully demonstrated the use of stainless steel (SS) wafer as a current collector to prepare binder free SU-8 derived carbon thin films. Standard carbon microelectromechanical systems (C-MEMS) process parameters were tuned to obtain a uniform, crack-free carbon thin film on SS wafer upon pyrolysis. Further, we varied the final pyrolysis temperature to examine its effect on the microstructure and composition as characterized with X-ray diffraction, Small angle X-ray scattering, Raman spectroscopy and CHNS-O elemental analyzer respectively. The microstructural changes in the carbon films at different pyrolysis temperature were then correlated with their electrochemical performance as investigated using galvanostat charge/discharge experiments, impedance spectroscopy and cyclic voltammetry. Selection of an appropriate current collector and optimizing the pyrolysis temperature yielded excellent cyclic stability and coulombic efficiency with 400 mAh g−1 reversible capacity after 100 cycles, nearly double to as reported in the literature.

Time-Resolved Study of Nanoparticle Induced Apoptosis Using Microfabricated Single Cell Arrays.

Cell fate decisions like apoptosis are heterogeneously implemented within a cell population and, consequently, the population response is recognized as sum of many individual dynamic events. Here, we report on the use of micro-patterned single-cell arrays for real-time tracking of nanoparticle-induced (NP) cell death in sets of thousands of cells in parallel. Annexin (pSIVA) and propidium iodide (PI), two fluorescent indicators of apoptosis, are simultaneously monitored after exposure to functionalized polystyrene () nanobeads as a model system. We find that the distribution of Annexin onset times shifts to later times and broadens as a function of decreasing NP dose. We discuss the mean time-to-death as a function of dose, and show how the value depends both on dose and time of measurement. In addition, the correlations between the early and late apoptotic markers indicate a systematic shift from apoptotic towards necrotic cell death during the course of the experiment. Thus, our work demonstrates the potential of array-based single cell cytometry for kinetic analysis of signaling cascades in a high-throughput format.

Restoration of chondrocytic phenotype on a two-dimensional micropatterned surface.

Chondrocytes within mature cartilage reside in a 3D matrix and adopt a distinctive round morphology. A vast 2D-culture surface is well-known to induce chondrocyte dedifferentiation characterized by the loss of spherical morphology and ceased expression of chondrogenic markers. Methods to restore chondrogenesis so far only occur on a certain level producing varied cell subpopulations and inferior cartilage matrix; the critical parameters, especially for the pericellular microenvironment, are still to be precisely determined. In this study, arrays of 2D circular micropatterns were designed to hold single subcultured chondrocytes with stable adhesion. The chondrocytes rounded up forming a 3D architecture; they remodeled their cytoskeleton to resemble in-situ chondrocytes and expressed collagen II instead of collagen I or fibronectin. This technique suggested that pure physical constraints can induce chondrocytic phenotype restoration on a 2D surface; it also provides a new design pathway to precisely control the microenvironment surrounding every chondrocyte therefore to unify the redifferentiation level of individual cell.

Improving LED CCT uniformity using micropatterned films optimized by combining ray tracing and FDTD methods.

Although the light-emitting diode (LED) has revolutionized lighting, the non-uniformity of its correlated color temperature (CCT) still remains a major concern. In this context, to improve the light distribution performance of remote phosphor LED lamps, we employ a micropatterned array (MPA) optical film fabricated using a low-cost molding process. The parameters of the MPA, including different installation configurations, positioning, and diameters, are optimized by combining the finite-difference time-domain and ray-tracing methods. Results show that the sample with the upward-facing convex-cone MPA film that has a diameter of half of that of the remote phosphor glass, and is tightly affixed to the inward surface of the remote phosphor glass renders a superior light distribution performance. When compared with the case in which no MPA film is used, the deviation of the CCT distribution decreases from 1033 K to 223 K, and the corresponding output power of the sample is an acceptable level of 85.6%. We perform experiments to verify our simulation results, and the two sets of results exhibit a close agreement. We believe that our approach can be used to optimize MPA films for various lighting applications.

Ultra uniform arrays of micro patterns on large area substrate by employing wet chemical etching

A wet chemical selective etching process is presented to delineate ultra-uniform micro patterns in the form of arrays of sensor chips of 4mm×4mm size in the matrix of 9×9 on a 3″ diameter silicon substrate with uniform physical and electrical characteristics. The selective etching of thin film is confined to the top area by masking its outer edges. This leads to uniform etching of the entire film leading to ultra-uniform delineation of arrays of micro patterns. The process has been verified over the selective etching of doped polysilicon in defining the polysilicon resistors and subsequently has been applied on realizing Ti/Au interconnecting lines using wet chemical etchant. Experimental results are presented with physical and electrical characteristics of the patterned structures in the statistical form over the substrate surface. SEM analysis is carried out for physical dimension measurement and standard deviation of 0.0040 is observed in polysilicon micro patterning. The process is competitive with reactive ion etching (RIE) in terms of yield, reliability and repeatability with cost effectiveness in a production environment. Methodology of ultra-uniform etching on entire substrate area is developed in support of the experimental results. The ratio of Top Surface Area (TSA) and Total Exposed Surface Area (TESA) is shown as crucial parameter for the uniform etching of thin films.

Relatively uniform and accelerated degradation of pure iron coated with micro-patterned Au disc arrays.

Pure iron has been proven to be a potential biodegradable metal, but its degradation rate was too slow. To accelerate its biodegradation, micro-patterned Au disc films were deposited on the surface of pure iron by vacuum sputtering. The influence of Au disc films on the degradation of pure iron matrix in vitro was investigated in the present study. Electrochemical measurement results indicated that the corrosion current density of pure iron coated with micro-patterned Au disc films in Hank's solution was 4 times larger than that of the uncoated one, while the difference between the influences of micro-patterned Au discs with different diameters on the corrosion rate of pure iron was insignificant. Immersion test indicated that the corrosion depth for pure iron coated with Au disc films was about three times as that of bare pure iron. Both electrochemical test and immersion test revealed that the corrosion of pure iron matrix coated with Au disc array became more uniform.

비이온계 계면활성제기반 고순도 알루미늄 습식식각을 통한 균일한 마이크로패턴 어레이 제작

ABSTRACT In this paper, the effects of a nonionic surfactant on the etch uniformity and the etch profile during the wet-etching process of high-purity aluminum were investigated for the fabrication of uniform micropattern arrays. To improve the surface roughness of a high-purity aluminum plate, a mechanical lapping process and an electrolytic polishing process were used. After electrolytic polishing process, the surface roughness, Ra, of the high-purity aluminum plate was improved from 1.25 ㎛ to 0.02 ㎛. A photoresist was used as an etching mask during the aluminum etching process, where the mixture of phosphoric acid, acetic acid, nitric acid, a nonionic surfactant and water was used as the aluminum etchant. Different amounts of the Triton X-100 nonionic surfactant were added to the aluminum etchant to investigate the effect of a nonionic surfactant during the wet-etching process of high-purity aluminum. The etch rate and the etch profile were measured by an optical interferometer and a scanning electron microscope.

Surface composition of solid oxide electrode structures by laterally resolved low energy ion scattering (LEIS)

Low Energy Ion Scattering (LEIS) is a powerful tool to analyse the composition of the very outermost atomic monolayer of a material. However, most studies so far have been conducted on ceramic pellets of the materials of interest. In this work, we apply laterally resolved LEIS analysis to electrochemical cells consisting of micro-patterned arrays of LSCF electrodes on YSZ electrolytes. The results suggest the migration of constituent elements and impurities between the two phases which has the potential to influence device performance.

Magnetophoretic-based microfluidic device for DNA isolation.

This paper presents a continuous flow microfluidic device for the separation of DNA from blood using magnetophoresis for biological applications and analysis. This microfluidic bio-separation device has several benefits, including decreased sample handling, smaller sample and reagent volumes, faster isolation time, and decreased cost to perform DNA isolation. One of the key features of this device is the use of short-range magnetic field gradients, generated by a micro-patterned nickel array on the bottom surface of the separation channel. In addition, the device utilizes an array of oppositely oriented, external permanent magnets to produce strong long-range field gradients at the interfaces between magnets, further increasing the effectiveness of the device. A comprehensive simulation is performed using COMSOL Multiphysics to study the effect of various parameters on the magnetic flux within the separation channel. Additionally, a microfluidic device is designed, fabricated, and tested to isolate DNA from blood. The results show that the device has the capability of separating DNA from a blood sample with a purity of 1.8 or higher, a yield of up to 33 μg of polymerase chain reaction ready DNA per milliliter of blood, and a volumetric throughput of up to 50 ml/h.

Measuring the spatial extent of texture pooling using reverse correlation

The local image representation produced by early stages of visual analysis is uninformative regarding spatially extensive textures and surfaces. We know little about the cortical algorithm used to combine local information over space, and still less about the area over which it can operate. But such operations are vital to support perception of real-world objects and scenes. Here, we deploy a novel reverse-correlation technique to measure the extent of spatial pooling for target regions of different areas placed either in the central visual field, or more peripherally. Stimuli were large arrays of micropatterns, with their contrasts perturbed individually on an interval-by-interval basis. By comparing trial-by-trial observer responses with the predictions of computational models, we show that substantial regions (up to 13 carrier cycles) of a stimulus can be monitored in parallel by summing contrast over area. This summing strategy is very different from the more widely assumed signal selection strategy (a MAX operation), and suggests that neural mechanisms representing extensive visual textures can be recruited by attention. We also demonstrate that template resolution is much less precise in the parafovea than in the fovea, consistent with recent accounts of crowding.

Selective Sintering of Metal Nanoparticle Ink for Maskless Fabrication of an Electrode Micropattern Using a Spatially Modulated Laser Beam by a Digital Micromirror Device

We demonstrate selective laser sintering of silver (Ag) nanoparticle (NP) ink using a digital micromirror device (DMD) for the facile fabrication of 2D electrode pattern without any conventional lithographic means or scanning procedure. An arbitrary 2D pattern at the lateral size of 25 μm × 25 μm with 160 nm height is readily produced on a glass substrate by a short exposure of 532 nm Nd:YAG continuous wave laser. The resultant metal pattern exhibits low electrical resistivity of 10.8 uΩ · cm and also shows a fine edge sharpness by the virtue of low thermal conductivity of Ag NP ink. Furthermore, 10 × 10 star-shaped micropattern arrays are fabricated through a step-and-repeat scheme to ensure the potential of this process for the large-area metal pattern fabrication.

Selective adsorption of bismuth telluride nanoplatelets through electrostatic attraction.

We demonstrate a facile technique to assemble solution phase-synthesized bismuth telluride (Bi2Te3) nanoplatelets into arrays of micropatterns. Aminosilane self-assembled monolayers (SAMs) are printed on silicon dioxide (SiO2) substrates using microcontact printing (μCP). The SAM printed surfaces are terminated with amine-groups allowing Bi2Te3 nanoplatelet selective adsorption by electrostatic attraction. Using Kelvin probe force microscopy, the electrical potential difference between aminosilane SAM and Bi2Te3 nanoplatelet surfaces is found to be ∼650 mV, which is larger than that (∼400 mV) between the SiO2 substrate and Bi2Te3 nanoplatelet surfaces. The selective adsorption provides an opportunity for integrating solution phase-grown topological insulators toward several device-level applications.

Micropatterned array to assess the interaction of single platelets with platelet factor 4-heparin-IgG complexes

We report a strategy to generate by electron beam lithography high fidelity micropatterned arrays to assess the interaction of single platelets with immobilised ligands. As a proof-of-principle we functionalised the microarrays with platelet factor 4 (PF4)-heparin-IgG complexes. We embedded biotinylated water-soluble quantum dots into polyethylene glycol (PEG)-coated micropatterned arrays and functionalised them via streptavidin to bind biotinylated ligands, here biotinylated-PF4/heparin complexes. The integrity of the PF4/heparin-complexes was shown by binding of anti-PF4/heparin antibodies. Ligand density was quantified by immunofluorescence and immunogold antibody labelling. Real-time calcium imaging was employed for read-out of single platelets activated on micropatterned surfaces functionalised with PF4/heparin-IgG complexes. With the smallest micropatterns (0.5x0.5 µm) we show that single platelets become strongly activated by binding to surface-immobilised PF4/heparin-IgG, while on larger micropatterns (10x10 µm), platelet aggregates formed. These findings that HIT antibodies can cause platelet activation on microarrays illustrate how this novel method opens new avenues to study platelet function at single cell level. Generating functionalized microarray surfaces to which highly complex ligands can be bound and quantified has the potential for platelet and other cell function assays integrated into high-throughput microfluidic microdevices.