Now showing items 1-20 of 35

    • Analysis of Scanned Probe Images for Magnetic Focusing in Graphene 

      Bhandari, Sagar; Lee, Gil-Ho; Kim, Philip; Westervelt, Robert M. (Springer Nature, 2017)
      We have used cooled scanning probe microscopy (SPM) to study electron motion in nanoscale devices. The charged tip of the microscope was raster-scanned at constant height above the surface as the conductance of the device ...
    • Automating Microfluidics: Reconfigurable Virtual Channels for Cell and Droplet Transport 

      Floryan, Caspar Jerzy; Nemiroski, Alex; Westervelt, Robert M. (2012-07-17)
      The emerging field of digital microfluidics promises to solve many shortcomings of traditional continuous-flow fluidics. This technology has a few incarnations, including EWOD (eletrowetting on dielectric) and DEP ...
    • Coaxial atomic force microscope probes for imaging with dielectrophoresis 

      Brown, Keith; Berezovsky, Jesse; Westervelt, Robert M. (AIP Publishing, 2011)
      We demonstrate atomic force microscope(AFM) imaging using dielectrophoresis(DEP) with coaxial probes. DEP provides force contrast allowing coaxial probes to image with enhanced spatial resolution. We model a coaxial probe ...
    • Coaxial Atomic Force Microscope Tweezers 

      Brown, Keith Andrew; Aguilar, J.A.; Westervelt, Robert M. (American Institute of Physics, 2010)
      We demonstrate coaxial atomic force microscope (AFM) tweezers that can trap and place small objects using dielectrophoresis (DEP). An attractive force is generated at the tip of a coaxial AFM probe by applying a radio ...
    • Density-Based Separations in Aqueous Multiphase Systems: Tools for Biological Research and Low-Cost Diagnostics 

      Kumar, Ashok Ashwin (2014-06-06)
      Cells often exist in heterogeneous mixtures. Density provides a property to separate several types of cells from the mixed sample in which they originate. Density-based separation methods provide a standard method to ...
    • Direct Imaging of Atomic-Scale Ripples in Few-Layer Graphene 

      Wang, Wei Li; Bhandari, Sagar; Yi, Wei; Bell, David C.; Westervelt, Robert M.; Kaxiras, Efthimios (American Chemical Society, 2012)
      Graphene has been touted as the prototypical two-dimensional solid of extraordinary stability and strength. However, its very existence relies on out-of-plane ripples as predicted by theory and confirmed by experiments. ...
    • Direct Observation of a Long-Lived Single-Atom Catalyst Chiseling Atomic Structures in Graphene 

      Wang, Wei Li; Santos, Elton J. G.; Jiang, Bin; Cubuk, Ekin Dogus; Ophus, Colin; Centeno, Alba; Pesquera, Amaia; Zurutuza, Amaia; Ciston, Jim; Westervelt, Robert M.; Kaxiras, Efthimios (American Chemical Society (ACS), 2014)
      Fabricating stable functional devices at the atomic scale is an ultimate goal of nanotechnology. In biological processes, such high-precision operations are accomplished by enzymes. A counterpart molecular catalyst that ...
    • Extracting the Density Profile of an Electronic Wave Function in a Quantum Dot 

      Boyd, Erin E.; Westervelt, Robert M. (American Physical Society, 2011)
      We use a model of a one-dimensional nanowire quantum dot to demonstrate the feasibility of a scanning probe microscope (SPM) imaging technique that can extract both the energy of an electron state and the amplitude of its ...
    • High Spatial Resolution Kelvin Probe Force Microscopy With Coaxial Probes 

      Brown, Keith A.; Satziner, Kevin J.; Westervelt, Robert M. (Institute of Physics, 2012)
      Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of ...
    • High Voltage Dielectrophoretic and Magnetophoretic Hybrid Integrated Circuit / Microfluidic Chip 

      Issadore, David; Franke, Thomas; Brown, Keith Andrew; Hunt, Thomas P; Westervelt, Robert M. (Institute of Electrical and Electronics Engineers, 2009)
      A hybrid integrated circuit (IC)/microfluidic chip is presented that independently and simultaneously traps and moves microscopic objects suspended in fluid using both electric and magnetic fields. This hybrid chip controls ...
    • Imaging Coherent Transport in Graphen (Part II): Probing Weak Localization 

      Berezovsky, Jesse; Westervelt, Robert M. (Institute of Physics, 2010)
      Graphene has opened new avenues of research in quantum transport, with potential applications for coherent electronics. Coherent transport depends sensitively on scattering from microscopic disorder present in graphene ...
    • Imaging Coherent Transport in Graphene (Part I): Mapping Universal Conductance Fluctuations 

      Berezovsky, Jesse; Borunda, Mario; Heller, Eric J.; Westervelt, Robert M. (Institute of Physics, 2010)
      Graphene provides a fascinating testbed for new physics and exciting opportunities for future applications based on quantum phenomena. To understand the coherent flow of electrons through a graphene device, we employ a ...
    • Imaging Cyclotron Orbits of Electrons in Graphene 

      Bhandari, Sagar; Lee, Gil-Ho; Klales, Anna Margaret; Watanabe, Kenji; Taniguchi, Takashi; Heller, Eric J.; Kim, Philip; Westervelt, Robert M. (American Chemical Society (ACS), 2016)
      Electrons in graphene can travel for several microns without scattering at low temperatures, and their motion becomes ballistic, following classical trajectories. When a magnetic field B is applied perpendicular to the ...
    • Imaging Electron Motion in a Few Layer MoS2 Device 

      Bhandari, Sagar; Wang, Ke; Watanabe, K; Taniguchi, T; Kim, Philip; Westervelt, Robert M. (IOP Publishing, 2017)
      Ultrathin sheets of MoS2 are a newly discovered 2D semiconductor that holds great promise for nanoelectronics. Understanding the pattern of current flow will be crucial for developing devices. In this talk, we present ...
    • Imaging electron motion in graphene 

      Bhandari, Sagar; Westervelt, Robert M. (IOP Publishing, 2017)
      A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's ...
    • Imaging Universal Conductance Fluctuations in Graphene 

      Borunda, Mario; Berezovsky, Jesse; Westervelt, Robert M.; Heller, Eric J. (American Chemical Society (ACS), 2011)
      We study conductance fluctuations (CF) and the sensitivity of the conductance to the motion of a single scatterer in two-dimensional massless Dirac systems. Our extensive numerical study finds limits to the predicted ...
    • An implantable wireless biosensor for the immediate detection of upper GI bleeding: a new fluorescein-based tool for diagnosis and surveillance (with video) 

      Ryou, Marvin K.; Nemiroski, Alex; Azagury, Dan; Shaikh, Sohail N.; Ryan, Michele B.; Westervelt, Robert M.; Thompson, Christopher C. (Elsevier BV, 2011)
      Background: Early recurrent hemorrhage after endoscopic intervention for acute upper GI bleeding (UGIB) can approach 20% and leads to increased morbidity and mortality. Little has changed over the past several decades ...
    • The Importance of Cantilever Dynamics in the Interpretation of Kelvin Probe Force Microscopy 

      Satzinger, Kevin J.; Brown, Keith A.; Westervelt, Robert M. (American Institute of Physics, 2012)
      A realistic interpretation of the measured contact potential difference (CPD) in Kelvin probe force microscopy (KPFM) is crucial in order to extract meaningful information about the sample. Central to this interpretation ...
    • Incorporation of Iron Oxide Nanoparticles and Quantum Dots into Silica Microspheres 

      Insin, Numpon; Tracy, Joseph B.; Lee, Hakho; Zimmer, John P.; Westervelt, Robert M.; Bawendi, Moungi G. (American Chemical Society, 2008)
      We describe the synthesis of magnetic and fluorescent silica microspheres fabricated by incorporating maghemite (γ-Fe2O3) nanoparticles (MPs) and CdSe/CdZnS core/shell quantum dots (QDs) into a silica shell around preformed ...
    • Integrated Circuit / Microfluidic Chip for Programmable Cell and Droplet Manipulation with Dielectrophoresis 

      Hunt, Thomas P; Issadore, David; Westervelt, Robert M. (Royal Society of Chemistry, 2008)
      We present an integrated circuit/microfluidic chip that traps and moves individual living biological cells and chemical droplets along programmable paths using dielectrophoresis (DEP). Our chip combines the biocompatibility ...