Adhesive Nano-Structures

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Nature provides remarkable examples of the use of patterning on micro and nanometer length scales to tailor adhesive behavior for specific environments. An exciting example that has just recently been understood after a century of inquiry is the gecko. Its feet are covered with a hierarchical hair-like structure that spans micro and nanometer scales. At the end, millions of spatulae, each on the order of 200-500 nm adhere to smooth and rough surfaces through van der Waals forces which operate only over a range of a few nm. Interestingly, while the van der Waals forces provide the molecular bonding forces, the geometry and topology of the hair-like structure plays a key role in determining the mechanics and physics of adhesion and decohesion. Motivated by these biological observations, we will explore the development and demonstration of high-performance design tools and nanofabrication techniques for the realization of nanostructures with engineered adhesive properties: the adhesion characteristics can be tailored to the individual application. This approach is to couple high-fidelity simulation tools capable of accurately modeling nano- and microscale surface force interactions, with shape and topology optimization tools allowing the tailoring of the adhesive properties. State-of-the-art nanofabrication technologies will then be used to realize the adhesive nanostructures, and an experimental nanomechanics program will be undertaken to validate the approach.The intellectual merit of our research is extensive. Not only does it bring together multiple cutting edge technologies that have yet to be thought of in concert, it makes advances in each individual technology: adhesion, micro/nanostructures, design, high-performance computing, and nanofabrication. The research also promises broader impact across an impressive spectrum of technologies in science, engineering, biology, and medicine beyond the specific tasks proposed. These include, but are not limited to: strategies to facilitate reliable nanomanufacturing processes such as soft lithography; the realization of novel dry adhesives for use at micro through macro scales; design technology to facilitate the nanofabrication of bonding sites for biological implants; surface engineering of MEMS components; and technology that can be used to design adhesive substrates for cell capture, adhesion, and growth. The graduate student (and undergraduate student that we will seek) will be exposed to a variety of techniques on the forefront of computational and experimental work as applied to nanotechnology. Specific attempts to recruit from underrepresented groups and women, in seeking qualified students.