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Steven D. Hudson

Research Interests:

Rheology, Interfacial Rheology, Microscopy, Microfluidics 

Research Opportunities:
National Research Council Fellowships
- Microfluidics for characterization of complex fluids
- rheo-SANS
- colloid rheology of shaped particles
- others

Fluid Suspensions and Emulsions project leader:

In the Fluid Suspensions and Emulsions Project, we are developing rheological measurement and data analysis methods to help take colloidal rheology beyond uniformly charged spheres to particles with more complex interactions.

Small Volume Rheology

The synergistic combination of morphology and rheology is instrumental for exploiting complex fluids, and is fundamental to polymer science. The Polymers and Complex Fluids Group is therefore developing methods to advance these measurement sciences. I am interested particularly in colloids, proteins, surfactants, interfacial phenomena and structure development. Through microfluidic device design, we (in the Fluid Suspensions and Emulsions project) control flow (type and strength) and measure fluid properties, aided by microscopic observations. 
I also contribute to the Organic Electronics and Photovoltaics Project, in which we are exploring morphology development in organic electronic materials.


 A series of drops flowing through a microchannel, extending when they accelerate through a constriction

Liquid drops undergoing extensional flow and deformation. The interfacial tension is measured by tracking drop position and shape (with Joao Cabral, Lab on a Chip).

 An image of particle streaks mapping out the flow inside a dropletAn image of a droplet's dilatational flow. An image of a droplet's shear flow.

The flow inside droplets (indicated by particle tracers) measures the interfacial mobility to dilatational (1st schematic) and shear deformations. This work is the foundation of a micro interfacial rheology method (with Jeff Martin, Kendra Erk, Fred Phelan, and Jonathan Schwalbe, Soft Matter).


An image of disclinations in an orientation map of a thin-film semiconducting polymerCover of Journal of Polymer Science Polymer Physics July 2011

An orientation map derived from dark-field TEM showing half-integer disclinations (with Xinran Zhang and Dean Delongchamp, Advanced Functional Materials). The color wheel identifies the orientation, and dislcinations are points where all of the colors converge. At positive disclinations (schematic at right) the colors appear in the same sequence as the color wheel (e.g., mapping counter clockwise around the disclinations the colors appear in the sequence: yellow, red, purple, blue).For negative disclinations the sequence is opposite. Six disclinations are circled; others are also present. A recent review that highlighted this work appeared on the cover of the Journal of Polymer Science Polymer Physics, July 2011; (The cover image is from the author of the review, Christopher McNeill).


Images of 300 nm patchy particles

TEM micrograph of polyelectrolyte multilayers and particle adsorption, as part of a step-by-step process metrology for particle lithography. This process produces patchy particles which aggregate in fluid suspensions (with Thuy Chastek, Langmuir).


Recent Invited Presentations

"Thin Film Morphology of Organic Electronic Materials," Northwestern U., Materials Science Department, November 16, 2010

"Career at a Government Lab," U. Akron, Research Experience for Undergraduates Seminar, August 3, 2010

"Microfluidics to study transport phenomena," S. D. Hudson et al., U. Akron, Polymer Science Seminar, August 3, 2010

"Microfluidics to study transport phenomena," U. Maryland, Chemical and Biomolecular Engineering Seminar, April 27, 2010.

"Microfluidic methods to measure surfactant dynamics," Procter and Gamble, April, 2010.

"Thin film morphology of organic electronic materials," Symposium in honor of Andrew Lovinger, American Chemical Society, San Francisco, March, 2010.

"Interfacial rheology," Mid-Atlantic Soft Matter Workshop, Johns Hopkins U, November, 2009.

"Polyelectrolyte and particle adsorption to nanopatterned surfaces", American Chemical Society, National Meeting, Colloid & Surface Science, Washington, DC, August, 2009.

"Rolling and Stretching; dynamical characterization of complex fluids", Physics Colloquium, Georgetown University, February, 2008.

"Microfluidic Methods for Emulsion and Particle Characterization,"2nd International Symposium on Polymer Materials Science, December, 2007.

"Microfluidic Methods for Emulsion and Particle Characterization," Gordon Research Conference on Polymer Colloids, Tilton, NH, June, 2007.

"Structural Analysis and Fluid Properties of Supramolecular Assemblies," American Physical Society, March Meeting, Denver, CO, March, 2007.

Awards and Honors:

  • US Department of Commerce, Bronze medal, 2012
  • Fellow, American Physical Society, 2007
    For excellence in structural studies of supramolecular and polymeric materials and the quantitative description of droplet and particle dispersion under quiescent and flow conditions.
  • Glennan Fellowship, Case Western Reserve Univeristy, 1997-1998
  • General Electric Scholarship, University of Massachusetts, 1985-1986.
  • McMullen Scholarship, Cornell University, 1981-1983.

Former Associates:

  • Prof. Joao Cabral, Imperial College, London
  • Dr. Thuy Chastek
  • Prof. Gordon Christopher, Mechanical Engineering, Texas Tech
  • Prof. Kendra Erk, Materials Engineering, Purdue University
  • Dr. Hua Hu, Procter & Gamble
  • Dr. Lucas Landherr, Chemical Engineering, Northeastern University
  • Dr. Joie Marhefka, Falcon Genomics
  • Dr. Jeffrey Martin, Johnson & Johnson
  • Dr. Jai Pathak, Medimmune
  • Dr. Prasad Sarangapani, Regeneron Pharmaceuticals
  • Dr. Jonathan Schwalbe, Johns Hopkins Applied Physics Laboratory
  • Dr. Paul Start, Intel
  • Dr. Philip Stone, USTC
  • Prof. Juan Taboas, U Pittsburgh



Created October 9, 2019