National Science Foundation     |     Directorate for Engineering  (ENG)
Division of Chemical, Bioengineering, Environmental, & Transport Systems  (CBET)
 
CBET Research Highlights 
Notable Accomplishments from CBET Awards
 
 
1415 - Part A - Nanoscale Dumbbells Make Smart Materials
 
Eric Dufresne  -  Yale University, New Haven, CT
Eric Furst  -  University of Delaware, Newark, DE

Accomplishment:  Researchers at Yale University and the University of Delaware have demonstrated a new concept for electric inks.  They were able to dynamically switch the color of a suspension from white to a vivid orange.  The key breakthrough was to give suspended nanoparticles a dumbbell shape, which causes them to line up when a voltage is applied.

Eric Dufresne Image 1
  Figure 1.  Macroscopic photograph of colors produced when dumbbell shaped nanoparticles are organized by an electric field.
 
Eric Dufresne Image 2
  Figure 2.  A microscopic electron micrograph of the organized dumbbell nanoparticles.
 
Eric Dufresne Image 3
  Figure 3.  A close-up view of microscopic electron micrograph of the organized dumbbell nanoparticles.
 
Credit for All Images:  Eric Dufresne, Yale University, New Haven, CT; Eric Furst, University of Delaware, Newark, DE

Impact:  Electronic information displays are rapidly proliferating to include cell phones, laptops, and media tablets.  Displays based on conventional LCD technology are energy hungry because they make their own light.  Suspension-based electrophoretic inks, which have become popular in electronic book readers, simply reflect light from their surroundings and are therefore much more energy efficient.  However, current technologies can only make black and white displays.  This research lays the groundwork for a new generation of energy efficient color displays.

Background:  This breakthrough was achieved by combining NSF supported research at Yale and Delaware.  The Yale team had developed an efficient and reliable approach to making large quantities on tiny and identical dumbbell-shaped particles.  The Delaware team had developed new approaches to organizing particles by applying a voltage to a suspension. When an electric field lines up these particles and organizes them onto a grid, the particles can cooperate to make brilliant colors in much the same way as a butterfly.  Unlike a butterfly, however, the colors can be turned on and off with an electric field.  In the long run, the researchers hope that such suspensions could be used to make energy efficient color displays, for a variety of consumer and industrial applications.



CBET Research Highlight - Part B - Engineering Technical Information

1415 - Nanoscale Dumbbells Make Smart Materials

Eric Dufresne  -  Yale University, New Haven, CT
Eric Furst  -  University of Delaware, Newark, DE

Background:  Please see paragraph above.

Results:  This work fuses NSF-supported research at Yale and Delaware.  The Yale team had developed an efficient and scalable approach to making nanoscale monodisperse polymer dumbbells.  While micron-scale dumbbell shaped polymer particles have been around since the 1980s, the Yale team came up with a new synthesis that allow for the creation of monodisperse particles ten times smaller.  The Delaware team developed new approaches to direct the assembly of colloidal suspensions using applied electric fields, allowing the efficient assembly of crystalline structures over wide areas.  Because of the non-spherical shape of these particles, they readily align with an external field.  Dipole forces and dielectrophoretic forces both facilitate the assembly of the particles into a crystalline structure.  The resulting crystalline structure has a partial photonic bandgap and shows pronounced birefringence.  Thanks to the photonic bandgap, the crystalline suspension has a vivid orange color.  When the electric field is removed, the crystal rapidly (~100ms) melts and becomes white.  This represents a new approach to creating materials field-addressable structural color.  In the long run, the researchers hope that such suspensions could be used to make energy efficient color displays, for a variety of consumer and industrial applications.

Scientific Uniqueness:  This NSF-supported research is unique since it . . .

This research highlight addresses CBET Strategic Outcome Goals as follows:
 
- 1Primary Strategic Outcome Goal:  Discovery:  This NSF-supported research has established . . .
 
- 2Secondary Strategic Outcome Goal:  Learning:  This project has provided research and education opportunities to ??? graduate students, and ??? undergraduate students.  Among these students, . . .

Transformative Research:  This work provides a new route to the assembly of photonic materials.  While previous work on self-assembled photonic materials was limited to static assemblies of spheres, this work creates dynamic photonic crystals by exploiting the asymmetric polarizability of the nanoscale dumbbell particles.  This provides a new intellectual framework for approaching the assembly of photonic materials and opens up new applications since the photonic properties can be modulated by electronics.

Intellectual Merit:  This work fuses NSF-supported research at Yale and Delaware.  The Yale team had developed an efficient and scalable approach to making nanoscale monodisperse polymer dumbbells.  While micron-scale dumbbell shaped polymer particles have been around since the 1980s, the Yale team developed a new synthesis that allowed for the creation of monodisperse particles ten times smaller.  The Delaware team developed new approaches to direct the self-assembly of colloidal suspensions using applied electric fields, allowing the efficient fabrication of crystalline structures over wide areas.  Because of the non-spherical shape of these particles, they readily align with an external field.  Dipole forces and dielectrophoretic forces both facilitate the assembly of the particles into a crystalline structure.  The resulting crystalline structure has a partial photonic bandgap and shows pronounced birefringence.  Thanks to the photonic bandgap, the crystalline suspension has a vivid orange color.  When the electric field is removed, the crystal rapidly (~100ms) melts and becomes white.  This represents a new approach to creating materials field-addressable structural color.

Broader Impacts of this research include:
 
- 1Benefits to society:  The organization of colloidal particles is the basis for display technologies that use far less energy than conventional LCDs, and these have become widely popular in electronic readers.  However, this energy saving technology cannot currently display vivid colors.  Field-addressable structural colors, such as those exhibited by dumbbell colloids, could potentially enable vibrant new display technologies.  Aside from these immediate applications, the Team’s studies of dumbbell particles have led to new discoveries for nanoparticle self-assembly, which will enable scalable nano-manufacturing processes across a wide range of technologies.  Such self-assembly harnesses nanoparticle building blocks to create sophisticated, functional nanomaterials.
 
- 2Broadening participation of underrepresented groups:  Graduate and undergraduate students from a wide range of backgrounds, including those underrepresented in STEM, have made contributions to this collaborative and dynamic team.
 
- 3Advancing discovery and understanding while promoting teaching, training, and learning:  The Delaware and Yale research teams consist of undergraduate, graduate and post-doctoral students.  This integrated research and educational program supports the US capacity for innovation towards global competitiveness, national security and quality of life.
 
- 4Disseminating broadly to enhance scientific and technological understanding:  Results from this project have been published in the journal ACS Nano, a leading journal on nanotechnology. (J. D. Forster, J.-G. Park, M. Mittal, H. Noh, C. F. Schreck, C. S. O’Hern, H. Cao, E. M. Furst, and E. R. Dufresne, “Assembly of optical scale dumbbells into dense photonic crystals,” ACS Nano 5, 6695-6700, 2011.)


 
Program Director:
 
 
 
Ashok Sangani
CBET Program Director - Particulate and Multiphase Processes
     
NSF Award Number:   0547294 - Eric R. Dufresne - Yale University
0930549 - Eric M. Furst - University of Delaware
     
Award Titles:   Eric R. Dufresne - CAREER: Self-Assembly and Direct Fabrication of Stimuli-Responsive Colloidal Materials Governed by Proteins to Enable Applications of Nanotechnology in Biology and Medicine
Eric M. Furst - Interactions and Self-assembly of Anisotropic Colloidal Particles in Electric Fields
     
Program Element Code:   1415
     
CBET Research Highlight:   Fiscal Year 2012
     
Approved by CBET on:   Pending
     
     


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This CBET Research Highlight was Updated on 25 July 2012.