Chaudhury elected Fellow of American Physical Society

Manoj Chaudhury, a respected and popular teacher whose research into adhesion has been praised for its simplicity and ingenuity, has been elected a Fellow of the American Physical Society.
Chaudhury, the Franklin J. Howes Jr. Distinguished Professor of Chemical and Biomolecular Engineering and former director of the Polymer Interfaces Center, was cited for “conducting fundamental studies on the roles of energetic and kinetic processes on adhesion, fracture and tribological properties of polymeric interfaces.”
APS has more than 45,000 members, including about 10,000 from other countries. About 200 members are elected Fellows each year, mostly for distinction in research. Chaudhury’s election, in early November, was recommended by APS’s division of polymer physics.
Chaudhury has published 100 papers in peer-reviewed journals, including the distinguished journals Science, Nature, Proceedings of the National Academy of Sciences, Proceedings of the Royal Society and Physical Review Letters. His papers have received about 3,700 citations. He holds several patents, is co-editor of the textbook Surfaces, Chemistry and Applications, and is associate editor of the new journal Biointerfaces.
In 2005, the Journal of Adhesion dedicated a six-issue set of papers in Chaudhury’s honor. The “Chaudhury Collections” include original papers by 30 international scientists.
Also last year, Chaudhury received the Award for Excellence in Adhesion Science from the Adhesion Society. The award, sponsored by 3M, cited Chaudhury “for exceptional creativity and ingenuity in research on adhesion and wetting and [for] the development of simple methods to measure the strength of attraction between materials.”
Other scientists have praised Chaudhury for “simple, ingenious and illuminating experiments” and for “research that is beautifully conceived, clarifies basic ideas, and immediately suggests ways in which it can be used practically.”
Chaudhury’s former students hold positions in academia, industry and government and have won numerous awards themselves.
“Professor Chaudhury has a contagious enthusiasm about science, about linking the things we see to the laws of physics,” says Katherine Vorvolakos, who received her Ph.D. in chemical engineering in 2003 and now works at the U.S. Food and Drug Administration. “He’s very Socratic, and an unrelenting perfectionist. He’s also accessible to all of us, and is in the laboratory very often, more so than many other professors.”
Commanding droplets to move
When conducting experiments, Chaudhury and his students like to use simple items to design and build their own equipment. This, he says, helps to ensure the uniqueness and originality of every graduate student’s research.
Chaudhury is credited with helping to launch a new field of interfacial fluid mechanics with the publication in Science in 1992 of an article he co-wrote with George M. Whitesides of Harvard University. In that article, the two researchers described a method they developed to make water droplets migrate on surfaces by controlling surface chemical forces. The discovery was featured on CNN, in The New York Times, in Scientific American and elsewhere.
“Our paper played a role in motivating other researchers to try to develop other techniques to induce drop movement on surfaces,” Chaudhury says. “These activities have given rise to a new field in microfluidics that goes by several names, including ‘digital fluidics’ and ‘drop reactor.’ The goal is to command droplets to move in prescribed positions, and to mix and carry out chemical reactions that might be of use in biotechnology.”
In 2001, writing again in Science, Chaudhury and two co-authors—John Chen, professor of chemical engineering at Lehigh, and Susan Daniel, a Ph.D. candidate in chemical engineering—reported a breakthrough in the new field: By condensing saturated steam over a surface with a tension gradient, they caused the droplets to move at a much faster speed, approaching 1 meter per second.
The high speed of the droplets, Chaudhury believes, stems from the asymmetric properties of the gradient surfaces, which “rectifies” the random motion and coalescence of the droplets.
“The practical side of this discovery,” he says, “is that the effect [increased speed of the droplets] can be used to design more efficient heat transfer devices, such as heat exchangers and heat pipes.”
Chaudhury and Daniel later expanded on the idea of drop ratchet to create various types of drop propulsion mechanisms on surfaces. Their latest work was published in 2005 in collaboration with Pierre Gilles de Gennes, former winner of the Nobel Prize in Physics. The potential for creating new types of microfluidic devices with their method was highlighted in an editorial article published in Analytical Chemistry.
The two Lehigh researchers also collaborated with L. Mahadevan of Harvard to induce a flexible hydrogel rod to move and mimic the movements of snails, worms and snakes. The researchers described this work in an article published in Proceedings of the National Academy of Sciences. Their work was also featured in the mainstream science media. Technology Review, MIT’s monthly magazine, said the new method “could lead to new motion techniques for tiny machines, including robots that inspect difficult-to-get-to nooks, and for manufacturing processes that involve moving substances across surfaces.” Scientific American said, “Similar soft solids have so far shown promise for applications including sensors and actuators.”
In addition to studying interfacial fluid mechanics, Chaudhury’s group has also made important contributions to the mechanics of soft materials. These studies combine molecular level investigations with continuum mechanics-level modeling to try to understand adhesive, fracture and tribological properties of surfaces. An important new discovery of Chaudhury’s group is a novel pattern-forming mechanism with soft elastic films that arise due to the competition between intermolecular and elastic forces in thin films. These self-organized patterns, once formed, can be permanently stored, which could have important applications in various lithographic and nanotechnology applications.
Chaudhury’s research is supported by the Office of Naval Research, the Pennsylvania Infrastructure Technology Alliance, Boeing, and National Starch & Chemical Company.
--Kurt Pfitzer