In-situ Plasma Studies using a Direct Current Microplasma in a Scanning Electron Microscope

Microplasmas can be used for a wide range of technological applications and to improve our understanding of fundamental physics. Scanning electron microscopy, on the other hand, provides insights into the sample morphology and chemistry of materials from the mm-down to the nm-scale. Combining both would provide direct insight into plasma-sample interactions in real-time and at high spatial resolution. Up till now, very few attempts in this direction have been made, and significant challenges remain. This work presents a stable direct current glow discharge microplasma setup built inside a scanning electron microscope. The experimental setup is capable of real-time in-situ imaging of the sample evolution during plasma operation and it demonstrates localized sputtering and sample oxidation. Further, the experimental parameters such as varying gas mixtures, electrode polarity, and field strength are explored and experimental $V$-$I$ curves under various conditions are provided. These results demonstrate the capabilities of this setup in potential investigations of plasma physics, plasma-surface interactions, and materials science and its practical applications. The presented setup shows the potential to have several technological applications, e.g., to locally modify the sample surface (e.g., local oxidation and ion implantation for nanotechnology applications) on the $\mu$m-scale.Comment: LG, DC, and RDM contributed equally to this work. The videos mentioned in the manuscript can be found in the Zenodo repository linked in the pape

Binding of fluid-phase P-selectin and Psgl-1 expression.

<p>Binding of P-selectin/IgM to peripheral blood leukocytes from (A) WT→B6 mice or (B) <i>Tpst</i> DKO→B6 mice. Shaded histograms represent binding of CD45/IgM. Binding of the anti-Psgl-1 mAb 2PH1 to peripheral blood leukocytes from (C) WT→B6 mice or (D) <i>Tpst</i> DKO→B6 mice. Shaded histograms represent binding of isotype control mAb. Panels A & C are same samples analyzed on the same day and are representative of 3 WT→B6 mice. Panels B & D are also same samples analyzed on the same day and are representative of 7 <i>Tpst</i> DKO→B6 mice. All analyses were gated on the neutrophil and monocyte population based on forward and orthogonal light scattering properties and on donor origin (CD45.2⁺).</p

Evaporation-Driven Crystallization of Diphenylalanine Microtubes for Microelectronic Applications

Self-assembly of supramolecular biomaterials such as proteins or peptides has revealed great potential for their use in various applications ranging from scaffolds for cell culture to light-emitting diodes and piezoelectric transducers. Many of these applications require controlled growth,of individual objects in the configuration allowing simple transfer to the desired device. In this work, we grew millimeter-long diphenylalanine (FF) self-assembled microtubes with high aspect ratio via evaporation-driven crystallization of nonsaturated FF solutions, making use of the Marangoni flow in the drying droplets. The growth mechanism was investigated by measuring the microtube length as a function of time. Jerky (steplike) growth behavior was observed and explained by a self-activated process in which additional activation energy is provided through condensation. The calculated growth rate due to the diffusion-controlled process is in agreement with the experimentally measured values. The grown microtubes were successfully transferred to metallized patterned substrates, and their specific conductivity and piezoelectric properties were evaluated as a function of the applied voltage and frequency. A number of piezoelectric resonances were observed and attributed to different vibrational modes excited by the piezoelectric effect inherent to the FF structure

Evaporation-Driven Crystallization of Diphenylalanine Microtubes for Microelectronic Applications

Self-assembly of supramolecular biomaterials such as proteins or peptides has revealed great potential for their use in various applications ranging from scaffolds for cell culture to light-emitting diodes and piezoelectric transducers. Many of these applications require controlled growth of individual objects in the configuration allowing simple transfer to the desired device. In this work, we grew millimeter-long diphenylalanine (FF) self-assembled microtubes with high aspect ratio via evaporation-driven crystallization of nonsaturated FF solutions, making use of the Marangoni flow in the drying droplets. The growth mechanism was investigated by measuring the microtube length as a function of time. Jerky (steplike) growth behavior was observed and explained by a self-activated process in which additional activation energy is provided through condensation. The calculated growth rate due to the diffusion-controlled process is in agreement with the experimentally measured values. The grown microtubes were successfully transferred to metallized patterned substrates, and their specific conductivity and piezoelectric properties were evaluated as a function of the applied voltage and frequency. A number of piezoelectric resonances were observed and attributed to different vibrational modes excited by the piezoelectric effect inherent to the FF structure