Abstract: The talk will concentrate on materials science and engineering aspects of the research undertaken in the NC State Center for Robotics and Intelligent Machines. Topics reviewed will include: miniature solid state actuator and motor design and fabrication, printing circuits onto textile substrates, and novel biomedical systems development. Basically, the talk will promote the benefits obtained through conducting multidisciplinary research.

February 28th, 2007 -- 5 pm, EB1 3035. Join us for pizza and a talk titled "Dendrimers and Patterned Surfaces: Electron Transfer 'to' and 'through' for Molecular Electronics" by Prof. Chris Gorman of the Chemistry Department at NCSU.

Brief Abstract: Recent work in the Gorman group has focused on the electronics behavior of molecular assemblies including dendrimers and self-assembled monolayers that are patterned and studied at the nanometer scale using scanning probe lithography. The goal of this talk is to indicate the role that these materials can play in the emerging field of molecular electronics and to provide a rational, chemical basis behind electronics behaviors in molecules. Full Abstract (.pdf)

March 28th, 2007 -- Join us at 5 pm in EB1 room 3035 for two student talks! Sharon Kiesel and Shalini Gupta will be talking to us about the work that they are presenting at the nationl MRS meeting. Their respective abstracts follow.

Sharon Kiesel - Single-Mode Polymer Optical Fiber Sensors for Large Strain Applications. An intrinsic, single-mode, polymer optical fiber (POF) sensor was characterized for use in large-strain applications such as civil infrastructures subjected to earthquake loading or systems with large shape changes such as morphing aircraft. The opto-mechanical response was formulated for the POF including a second-order (in strain) photoelastic effect as well as a second-order (in strain) solution for the deformation of the POF during loading. It is shown that four independent mechanical and opto-mechanical constants are required for the small deformation regime and six additional independent mechanical and opto-mechanical constants are required for the large deformation regime. The mechanical nonlinearity of a typical polymer optical fiber was experimentally measured in tension at various loading rates. The secant modulus of elasticity measured at small strains, roughly up to 2% strain, was measured to be ~4GPa whereas at larger strains, roughly up to 4.5% strain, the secant modulus was measured to be ~4.8GPa. As the loading rate was increased the yield strain increased, ranging from ~3.2% at 1mm/min to ~5% at 305 mm/min.

Shalini Gupta - Engineered Co-assembly of Biocomposite Materials from Live Cells and Inorganic Particles Using Dielectrophoresis on a Chip - The co-assembly of live cells and synthetic colloidal particles could be a route to making new hybrid biomaterials, in which the biological functionality of the cells is augmented by the physical functionality of the inorganic particles. We demonstrate how such biocomposite materials can be fabricated by rapid and controlled electric field driven assembly on a chip. The process is based on dielectrophoresis (DEP), mobility and interaction of particles in AC electric fields. Live cells such as baker's yeast and NIH/3T3 mouse fibroblasts were co-assembled with colloidal particles into freely suspended 1D "wires" and 2D membranes. Experimental observations of the DEP co-assembly dynamics showed that particles smaller in size than the cells were drawn and captured in-between the cell junctions by the electric field. The process could be modeled and understood by a combination of electrostatic field computation and MD-type of particle motion simulation. The effects of voltage, frequency, pH and electrolyte concentration will be discussed. Magnetic microparticles conjugated with lectins could be used to bind the cells irreversibly via bio-specific lectin-polysaccharide interactions. The formed membranes and wires could be manipulated by magnetic field and interfaced with on-chip electrodes. Such functional biomagnetic cell-particle assemblies may find applications in sensors, microassays, microsurgery, or as responsive biomaterials.

April 25th, 2007 -- The last meeting of the semester will be held at 5 pm in Room 3035 EB1 on Centennial Campus. Our speaker will be Dr. Stefan Seelecke from Mechanical and Aerospace Engineering and he will be presenting a talk entitled "Smart Materials and Structures." (pdf abstract) We will have pizza and refreshments available, as well as a little extra treat!

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