Electrical and Electronic Engineering - Research Publications

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    Polymeric Nanoneedle Arrays Mediate Stiffness‐Independent Intracellular Delivery (Adv. Funct. Mater. 3/2022)
    Yoh, HZ ; Chen, Y ; Aslanoglou, S ; Wong, S ; Trifunovic, Z ; Crawford, S ; Lestrell, E ; Priest, C ; Alba, M ; Thissen, H ; Voelcker, NH ; Elnathan, R (Wiley, 2022-01)
    In article number 2104828, Yaping Chen, Nicolas H. Voelcker, Roey Elnathan, and co-workers demonstrate the fabrication of relatively low-cost and high throughput polymeric nanoneedles from cell culture polystyrene. The nanoneedles with precise geometry are imprinted directly on polystyrene from the cell culture petri dish via nanoimprint lithography. The nanoneedles arrays can precisely manipulate cellular processes and mediate intracellular delivery in mammalian cells. This presents opportunities for novel integration of nanostructures into traditional polymeric cell cultureware.
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    Low‐Temperature Solution‐Processed Transparent QLED Using Inorganic Metal Oxide Carrier Transport Layers (Adv. Funct. Mater. 3/2022)
    Yu, Y ; Liang, Y ; Yong, J ; Li, T ; Hossain, MS ; Liu, Y ; Hu, Y ; Ganesan, K ; Skafidas, E (Wiley, 2022-01)
    In article number 2106387, Yang Yu, Efstratios Skafidas, and co-workers present transparent and fully solution processed inorganic quantum dots LED (QLED). To improve upon the structures hole injection efficiency, a low-temperature sol-gel derived copper doped NiO interlayer is introduced. The derived QLED analytical models and simulation results are in good concordance with experimental results, providing a new framework for the development of novel QLEDs.
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    Display of Native Antigen on cDC1 That Have Spatial Access to Both T and B Cells Underlies Efficient Humoral Vaccination.
    Kato, Y ; Steiner, TM ; Park, H-Y ; Hitchcock, RO ; Zaid, A ; Hor, JL ; Devi, S ; Davey, GM ; Vremec, D ; Tullett, KM ; Tan, PS ; Ahmet, F ; Mueller, SN ; Alonso, S ; Tarlinton, DM ; Ploegh, HL ; Kaisho, T ; Beattie, L ; Manton, JH ; Fernandez-Ruiz, D ; Shortman, K ; Lahoud, MH ; Heath, WR ; Caminschi, I (American Association of Immunologists, 2020-10-01)
    Follicular dendritic cells and macrophages have been strongly implicated in presentation of native Ag to B cells. This property has also occasionally been attributed to conventional dendritic cells (cDC) but is generally masked by their essential role in T cell priming. cDC can be divided into two main subsets, cDC1 and cDC2, with recent evidence suggesting that cDC2 are primarily responsible for initiating B cell and T follicular helper responses. This conclusion is, however, at odds with evidence that targeting Ag to Clec9A (DNGR1), expressed by cDC1, induces strong humoral responses. In this study, we reveal that murine cDC1 interact extensively with B cells at the border of B cell follicles and, when Ag is targeted to Clec9A, can display native Ag for B cell activation. This leads to efficient induction of humoral immunity. Our findings indicate that surface display of native Ag on cDC with access to both T and B cells is key to efficient humoral vaccination.
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    Investigation of Gallium–Boron Spin‐On Codoping for poly-Si/SiOx Passivating Contacts
    Truong, TN ; Le, TT ; Yan, D ; Phang, SP ; Tebyetekerwa, M ; Young, M ; Al-Jassim, M ; Cuevas, A ; Macdonald, D ; Stuckelberger, J ; Nguyen, HT (Wiley, 2021-12)
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    Investigation of Gallium–Boron Spin-On Codoping for poly-Si/SiOx Passivating Contacts
    Truong, TN ; Le, TT ; Yan, D ; Phang, SP ; Tebyetekerwa, M ; Young, M ; Al-Jassim, M ; Cuevas, A ; Macdonald, D ; Stuckelberger, J ; Nguyen, HT (Wiley, 2021-12-01)
    A doping technique for p‐type poly‐Si/SiOx passivating contacts using a spin‐on method for different mixtures of Ga and B glass solutions is presented. Effects of solution mixing ratios on the contact performance (implied open circuit voltage iVoc, contact resistivity ρc) are investigated. For all as‐annealed samples at different drive‐in temperatures, increasing the percentage of Ga in the solution shows a decrement in iVoc (from ∼680 to ∼610 mV) and increment in ρc (from ∼3 to ∼800 mΩ cm2). After a hydrogenation treatment by depositing a SiNx/AlOx stack followed by forming gas annealing, all samples show improved iVoc (∼700 mV with Ga‐B co‐doped, and ∼720 mV with all Ga). Interestingly, when co‐doping Ga with B, even a small amount of B in the mixing solution shows negative effects on the surface passivation. Active and total dopant profiles obtained by electrical capacitance voltage and secondary‐ion mass spectrometry measurements, respectively, reveal a relatively low percentage of electrically‐active Ga and B in the poly‐Si and Si layers. These results help understand the different features of the two dopants: a low ρc with B, a good passivation with Ga, their degree of activation inside the poly‐Si and Si layers, and the annealing effects.
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    Bottom-Up Synthesis of Single Crystal Diamond Pyramids Containing Germanium Vacancy Centers
    Nonahal, M ; White, SJU ; Regan, B ; Li, C ; Trycz, A ; Kim, S ; Aharonovich, I ; Kianinia, M (WILEY, 2021-07)
    Abstract Diamond resonators containing color‐centers are highly sought after for application in quantum technologies. Bottom‐up approaches are promising for the generation of single‐crystal diamond structures with purposely introduced color centers. Here the possibility of using a polycrystalline diamond to grow single‐crystal diamond structures by employing a pattern growth method is demonstrated. For, the possible mechanism of growing a single‐crystal structure with predefined shape and size from a polycrystalline substrate by controlling the growth condition is clarified. Then, by introducing germanium impurities during the growth, localized and enhanced emission from fabricated pyramid shaped single‐crystal diamonds containing germanium vacancy (GeV) color centers is demonstrated. Finally, linewidth of ∼500 MHz at 4 K from a single GeV center in the pyramid shaped diamonds is measured. The method is an important step toward fabrication of 3D structures for integrated diamond photonics.
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    Input-mapping based data-driven model predictive control for unknown linear systems via online learning
    Yang, L ; Li, D ; Ma, A ; Xi, Y ; Pu, Y ; Tan, Y (WILEY, 2022-01-01)
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    Progress and Future Prospects of Wide-Bandgap Metal-Compound-Based Passivating Contacts for Silicon Solar Cells
    Gao, K ; Bi, Q ; Wang, X ; Liu, W ; Xing, C ; Li, K ; Xu, D ; Su, Z ; Zhang, C ; Yu, J ; Li, D ; Sun, B ; Bullock, J ; Zhang, X ; Yang, X (WILEY-V C H VERLAG GMBH, 2022-07)
    Advanced doped-silicon-layer-based passivating contacts have boosted the power conversion efficiency (PCE) of single-junction crystalline silicon (c-Si) solar cells to over 26%. However, the inevitable parasitic light absorption of the doped silicon layers impedes further PCE improvement. To this end, alternative passivating contacts based on wide-bandgap metal compounds (so-called dopant-free passivating contacts (DFPCs)) have attracted great attention, thanks to their potential merits in terms of parasitic absorption loss, ease-of-deposition, and cost. Intensive research activity has surrounded this topic with significant progress made in recent years. Various electron-selective and hole-selective contacts based on metal compounds have been successfully developed, and a champion PCE of 23.5% has been achieved for a c-Si solar cell with a MoOx -based hole-selective contact. In this work, the fundamentals and development status of DFPCs are reviewed and the challenges and potential solutions for enhancing the carrier selectivity of DFPCs are discussed. Based on comprehensive and in-depth analysis and simulations, the improvement strategies and future prospects for DFPCs design and device implementation are pointed out. By tuning the carrier concentration of the metal compound and the work function of the capping transparent electrode, high PCEs over 26% can be achieved for c-Si solar cells with DFPCs.
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    Polymeric Nanoneedle Arrays Mediate Stiffness-Independent Intracellular Delivery
    Yoh, HZ ; Chen, Y ; Aslanoglou, S ; Wong, S ; Trifunovic, Z ; Crawford, S ; Lestrell, E ; Priest, C ; Alba, M ; Thissen, H ; Voelcker, NH ; Elnathan, R (WILEY-V C H VERLAG GMBH, 2022-01)
    Abstract Tunable vertically aligned nanostructures, usually fabricated using inorganic materials, are powerful nanoscale tools for advanced cellular manipulation. However, nanoscale precision typically requires advanced nanofabrication machinery and involves high manufacturing costs. By contrast, polymeric nanoneedles (NNs) of precise geometry can be produced by replica molding or nanoimprint lithography—rapid, simple, and cost‐effective. Here, cytocompatible polymeric arrays of NNs are engineered with identical topographies but differing stiffness, using polystyrene (PS), SU8, and polydimethylsiloxane (PDMS). By interfacing the polymeric NN arrays with adherent and suspension mammalian cells, and comparing the cellular responses of each of the three polymeric substrates, the influence of substrate stiffness from topography on cell behavior is decoupled. Notably, the ability of PS, SU8, and PDMS NNs is demonstrated to facilitate mRNA delivery to GPE86 cells with 26.8% ± 3.5%, 33.2% ± 7.4%, and 30.1% ± 4.1% average transfection efficiencies, respectively. Electron microscopy reveals the intricacy of the cell–NN interactions; and immunofluorescence imaging demonstrates that enhanced endocytosis is one of the mechanisms of PS NN‐mediated intracellular delivery, involving the endocytic proteins caveolin‐1 and clathrin heavy chain. The results provide insights into the interfacial interactions between cells and polymeric NNs, and their related intracellular delivery mechanisms.
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    Role of actin cytoskeleton in cargo delivery mediated by vertically aligned silicon nanotubes
    Chen, Y ; Yoh, HZ ; Shokouhi, A-R ; Murayama, T ; Suu, K ; Morikawa, Y ; Voelcker, NH ; Elnathan, R (BMC, 2022-09-08)
    Nanofabrication technologies have been recently applied to the development of engineered nano-bio interfaces for manipulating complex cellular processes. In particular, vertically configurated nanostructures such as nanoneedles (NNs) have been adopted for a variety of biological applications such as mechanotransduction, biosensing, and intracellular delivery. Despite their success in delivering a diverse range of biomolecules into cells, the mechanisms for NN-mediated cargo transport remain to be elucidated. Recent studies have suggested that cytoskeletal elements are involved in generating a tight and functional cell-NN interface that can influence cargo delivery. In this study, by inhibiting actin dynamics using two drugs-cytochalasin D (Cyto D) and jasplakinolide (Jas), we demonstrate that the actin cytoskeleton plays an important role in mRNA delivery mediated by silicon nanotubes (SiNTs). Specifically, actin inhibition 12 h before SiNT-cellular interfacing (pre-interface treatment) significantly dampens mRNA delivery (with efficiencies dropping to 17.2% for Cyto D and 33.1% for Jas) into mouse fibroblast GPE86 cells, compared to that of untreated controls (86.9%). However, actin inhibition initiated 2 h after the establishment of GPE86 cell-SiNT interface (post-interface treatment), has negligible impact on mRNA transfection, maintaining > 80% efficiency for both Cyto D and Jas treatment groups. The results contribute to understanding potential mechanisms involved in NN-mediated intracellular delivery, providing insights into strategic design of cell-nano interfacing under temporal control for improved effectiveness.