"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
An improved understanding of the nanometer-scale motion of fluids is central to the development of our understanding of complex fluids and biomolecules. The PI proposes to develop an instrument that measures the forces acting during the natural motion of molecules and fluids, with capabilities that exceed all current instruments. This instrument will measure the correlated motion of two antiparallel cantilevers that have atomic force microscope (AFM) tips or colloidal spheres attached to the free ends. The fluid between the tips will couple the two cantilevers such that the correlated motion is sensitive only to the intervening fluid. This antiparallel arrangement will greatly diminish the contribution of the cantilevers compared to conventional AFM. Measurement of the correlated motion results in a large increase in signal-to-noise ratio because the correlation is not sensitive to electronic, optical or mechanical disturbances on individual cantilevers. Moreover, even the thermal noise on the individual cantilever is not part of the correlation signal, so the instrument will have a lower noise floor than is theoretically possible for existing single cantilever AFM techniques. The instrument will be capable of measuring the mechanical properties of individual molecules tethered between the two cantilevers, as well as the viscoelastic properties of complex fluids with nanometer resolution at frequencies up to hundreds of kHz. Also, the simplicity of the mechanical concept provides a relatively easy path for ultimate development of an inexpensive and small instrument.
The development of new nanotechnologies requires new techniques for understanding the properties of matter on very small length scales. The outcomes of this project were all related to the development of new instrumentation to measure the properties of single molecules or small collections of molecules. We developed an apparatus in which two microscopic springs were positioned very close to each other such that a single molecule could be tethered between them. By studying how the vibrations of the springs were altered by the presence of the single molecule, we were able to determine the stiffness of the molecule and the damping effect of the molecule. There is an increasing trend to make products that are very small, either to pack more memory or computing power into a small object or simply to save on materials. The use of very small sampling devices or moving devices sometime requires control of the gas moving through or around the device. In this project we developed and understood a new method of controlling the flow of gas in small objects. This was done by coating the objects in a thin organic film, and then altering the properties of the film. We also developed a new method of analyzing very small amounts of liquids. We also trained four graduate students, one of whom has already graduated with a Doctorate and is now developing new products in industry, and the other three will graduate in 2014, and probably go on to become Professors. Three undergraduates were also trained in scientific techniques, one has graduated and gone on to industry, while the other two will graduate this year or next year. Several groups of female high school students were taught about microscopic measurement techniques as part of this project.
