Associate Professor of Physics
B.S., Physics, 1995, University of California at Los Angeles. Ph.D., Physics, 2001, University of Chicago. Post-doctoral Associate, Physics and Division of Engineering and Applied Science, Harvard University, 2001-2005. Assistant Professor, Physics, Cornell University, 2005 - 2011. Associate Professor, Physics, Cornell University, 2011 - present.
My lab studies emergent physical phenomena that arise from interactions between solid structures – ranging from microscopic particles to macroscopic solid surfaces – and the fluids in which they are embedded. These complex materials are typically out-of-equilibrium and driven beyond their linear response regime. Understanding their mechanical behavior often requires the development of new experimental techniques, analysis tools, and theoretical models. Working towards a fundamental understanding of how these materials respond to various stimuli including shear, electromagnetic fields, acoustical vibrations, and confinement will have a profound effect on our society, ultimately leading to the development of strain stiffening gels for next generation replacement tissues, detergents and pastes whose flow properties can be manipulated, and even small insect mimicking machines that flap their wings to fly.
We focus on three areas at the forefront of this broad field: I) Colloidal suspensions –
where the interactions between microscopic particles suspended in a fluid control the material properties; II) Biological tissues – where the organization of cells and biopolymer networks within the fluid controls tissue properties; III) Fluid-membrane interfaces – where the interaction between a fluid and a liquid or solid interface controls the resulting flows. Understanding the nested physical principles that act on different length scales in such materials remains one of the most challenging and interesting problems in the field of Soft Condensed Matter Physics.
One of our main goals is to develop instruments and techniques for simultaneous imaging of the material structure and measurement of its flow properties. To this end, we have built shear cells that can be loaded onto a confocal microscope. These devices allow us to simultaneously image the 3-D structure of materials such as a colloidal suspension or biological tissues while measuring the amount of force necessary to shear them. In this way, the link between material structure at the micron scale and the material properties at the macroscopic scale can be investigated quantitatively.
Fast Video Image Analysis
We have developed 3D image analysis techniques for extracting insect flight kinematic data from high speed videos. Our main goal has been to automate our image extraction so that significantly larger data sets can be attained and analyzed.
This research is inherently interdisciplinary in nature. To this end, we collaborate with numerous other groups on campus with the aim of producing research results that are greater in scope than the simple cumulative contributions of each individual research group. Nevertheless, my group’s ability to design and build table top experiments that combine custom built force measuring devices with techniques in photolithography, microscopy, confocal microscopy, light scattering, high speed imaging, and image analysis, allows us to develop novel approaches for investigating these materials and make unique contributions to these studies.
John Mergo, Jesse Silverberg, Neil Lin, Brian Leahy, Lena Bartell