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Initiative I: Engineering Living Cells via Nanomaterials

Senior Investigators:

Research Goals:

The long-term intellectual goal of this group is to develop a fundamental, generalizable understanding of how nanoparticles and polymer multilayers can be designed to integrate with living cells in ways that preserve cell viability and cellular processes while allowing materials to carry out engineered functions. These basic principles will enable rational selection of nanomaterials for diverse applications (such as drug delivery, tissue engineering, lab-on-chip/microfluidic technologies, biosensors and medical imaging, or therapeutic strategies based on nanomaterial-modified cells), suggest directions for the development of new materials for these applications, and allow us to systematically explore societal concerns relating to the potential toxicity of nanomaterials in vivo. Further, the new materials developed in this work will expand our understanding of synthetic nanomaterial structure/property relationships per se.

 

Research Highlights:

Stem cells with drug-loaded nanoparticles attached promote rapid recovery following bone marrow transplants
Living cells fitted with “nano-backpacks” may ferry drugs to disease sites

Initiative II: New States of Frustrated and Correlated Materials

Senior Investigators:

Research Goals:

Our group will focus on materials based on two-dimensional triangular and kagomé lattices, an area that we have pioneered as a small initiative during the previous funding cycle. The materials developed during the initiative period have attracted much interest and will serve as launching points for delving further in exciting new directions, such as probing exotic states of quantum matter that contain “topological order.”  This new order leads to a host of fascinating properties, such as fractional quantum numbers, non-Abelian statistics, emergent photons, and more.  Quantum spins on a kagomé lattice may exhibit this novel type of topological order which would have possible applications in quantum computing.  The addition of mobile charge carriers into these systems may lead to unconventional superconductivity and non-Fermi liquid ground states.  There is clearly much interesting territory to explore once candidate samples are synthesized. Our objective is to identify and synthesize new states of matter based on frustrated spin systems.

 

Research Highlights:

New technique reveals nanoscale variations in “bulk” material properties

 

Seed I: Nanoparticle Control and Transport using Mobile Magnetic Domain Wall Traps

Geoffrey Beach, Assistant Professor, Department of Materials Science & Engineering

This research seeks to develop an on-chip system for the capture, manipulation, and transport of individual magnetic nanoparticles for applications in, e.g., magnetic sorting of biomolecular entities. 

It is expected that a working prototype of a nanoparticle transport system with integrated single-particle detection will be developed and demonstrated.  The results are widely relevant to a variety of key research areas including cell sorting, pathogen detection, chemical and biological agent detection, and controlled nanoscale assembly.

Figure: Stray magnetic field from domain wall in magnetic wire with cross-section 10nm x 100nm, and schematic of motion of a "trapped" magnetic nanoparticle.

 

Research Highlight:

Nanoparticle control and transport using mobile magnetic domain wall traps

 

Seed II: Ultrafast Dynamics of Low Energy Excitations in Frustrated Materials

Nuh Gedik, Assistant Professor, Department of Physics

The goal of this seed project is to understand the emergent macroscopic properties of magnetically frustrated materials by studying the dynamics of their low energy excitations and phase transitions with the use of novel time resolved techniques. In these experiments, the material is excited by an ultrashort laser pulse and the recovery of the resulting state back to the ground state is probed with femtosecond temporal and sub-Angstrom spatial resolutions. The PI has developed different methods to selectively generate and probe charge, spin or lattice excitations in quantum materials. The information that will be obtained from these measurements will help us to understand the properties of the ground state (i.e. test whether a spin liquid behavior is realized), low energy excitations and phase diagram.

Figure: (a) Principle of ultrafast electron diffraction (UED). (b) Three dimensional model of the ultrahigh vacuum chambers to be used for UED and time and angle resolved photoemission spectroscopy.

 

Seed III: Tailoring Optical Properties of Semiconductor Nanomaterials

Silvija Gradečak, Assistant Professor, Department of Materials Science and Engineering

This project will concentrate on direct correlation of structural/optical properties with high spatial resolution, where semiconductor nanowires will serve as a model system. Ultimately, it seeks to answer the following questions: (1) what are the critical structure-property relationships in semiconductor nanowires and nanowire heterostructures that govern electrical and optical properties on the nanoscale? (2) How can this knowledge be used to predict and tailor properties of semiconductor nanowires (materials-on-demand) for specific applications in nanophotonics and nanoelectronics?

The approach combines novel nanowire growth techniques and in-situ electron microscopy characterization techniques for direct correlation of structural and physical properties on the nanoscale.  Cathodoluminescence (CL) in scanning transmission electron microscopy (STEM) is one of the techniques that will be of particular importance for this study. CL-STEM has recently been installed in the CMSE electron microscopy center (as the only instrument of its kind in the U.S.). It is anticipated that this seed research will significantly contribute to fundamental understanding of optical properties of 1D systems through a combination of rational nanowire synthesis, comprehensive structural and optical characterization, and electrical measurements.

Figure: Schematic drawing of the collection of CL in the TEM-CL that consists of the TEM, monochromator, and photodetectors.

Seed IV: Suspended Graphene Devices for Quantum Electronics and Nanosensing

Pablo Jarillo-Herrero, Assistant Professor, Department of Physics

The research objective of this seed project is to investigate electronic transport in ultra-high mobility suspended graphene devices (GDs) both to study fundamental quantum electronics and to assess their potential as chemical and mass nanosensors.

A crucial element of this research is the fabrication of high-quality suspended GDs. Multiterminal devices (see Figure below) will be used to study fundamental quantum phenomena, such as the fractional quantum Hall effect or the spin Hall effect, while high quality suspended GNRs will be actuated as tunable high-frequency nanoresonators. In addition, the possibility of passivating the edges of GNRs with desired chemical groups will enable ultra-sensitive chemical and mass detection.

Figure: (a) AFM picture of a graphene bipolar superconducting transistor. (b) AFM (phase) picture of crystallographic cuts on single layer graphene. Notice that all cuts (bright lines) form 60° or 120° angles, indicating the preservation of chirality. (c) Resistivity vs gate voltage for a suspended graphene FET with a room temperature mobility of 30,000 cm2/V?s. (d) SEM image of nanostructured graphene (bars, ribbons and constrictions) with contact electrodes and top gate electrodes for lateral heterodensity junctions.

 

 

Research Highlight:

Single atom-thick nano sensors

 

Seed V: Large Area, Few-layer Graphene Films for Various Applications

Jing Kong, Assistant Professor, Department of EECS

Graphene is the hexagonal arrangement of carbon atoms forming a one-atom thick planar sheet.  This layer is the building block of graphite and carbon nanotubes and it has been studied widely-by-theorists since the middle of the last century. Graphene sheets show great potential as another materials option for electronics applications. The overall goal of this seed project is to engineer the underlying metal substrate to achieve regular grain boundaries and facilitate graphene films with controlled morphology.

This seed work is divided into three parts:
1) Substrate engineering to achieve single crystal grains with regular grain boundaries

2) Investigation of the CVD growth with other types of metal substrates

3) Combining Parts 1 and 2 and identifying the optimized substrate for graphene morphology engineering

Figure: (A) Optical image of graphene grown on Ni.  The darker regions are thicker graphene regions, the arrows point to the 1-2 layer regions, which correspond to the regions pointed out by the arrows in (B). (B) The same graphene layer in (A) transferred onto SiO2/Si substrate. (C) An enlarged image of as-grown graphene on Ni showing thicker graphenes are grown over the grain boundary regions. (D) Another graphene film transferred to a SiO2/ Si substrate with a different morphology. Different film morphologies can be obtained by tunning CVD parameters such as cooling rate. (E) A schematic representation of the increase in atomic steps at the grain boundary region.

 

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