Improving Particle Function by Surface Modification
Particle surface modification is the focus of research by Senior University Professor Richard Partch and his group at CAMP. Continuing projects being investigated include:
1) chemical precipitation of single and mixed dopants onto metal oxide nanoparticles for microelectronic applications;
2) modification of abrasive solids with polymers for use in CMP slurries;
3) preparation of injectable microemulsion and particulate species for selective in vivo removal of overdosed chemical therapeutics and toxins. This biomedical related research is being carried out in collaboration with medical and scientific personnel at the University of Florida and is funded by NIH for the next three years. To-date in vivo experiments show great promise that the objective can be achieved without causing unwanted side effects (See Figure 2.);
4 ) deposition of functional polymers and self assembly of nanoparticles onto solids for components to improve the drying time and dye stability of imaging inks (See Figure 3.);
5) evaluation of laser-induced methods for reducing the size of aggregated particles in liquid dispersion;
6) use of photodecarboxylation as a method to control the volume shrinkage of filled resins when undergoing curing;
7) synthesis of high aspect ratio metal and metal coated species having high extinction coefficients for infrared radiation; and
8) encapsulation of enzyme particles with ionic liquids.
New projects include the preparation of new phosphor powders for improved lighting; and, encapsulation of metallic radio pharmaceuticals for biocompatibility. The latter is in collaboration with Dr. Enrique Pasqualini at the Institute for Nuclear Science, Buenos Aires, Argentina. It is funded by the International Atomic Energy Commission.
Electrochemical methods provide inexpensive and powerful tools to deposit nanostructures and to tailor the nanostructure of existing surfaces. CAMP Professor Ian Suni is investigating the electrochemical deposition and dissolution of metals to form controlled nanostructures for applications to semiconductor processing, catalysis, and biosensor development. In one current CAMP project (in collaboration with ReynoldsTech in Syracuse, New York) he is investigating an electrochemical method for depositing a Cu seed layer atop the Ta barrier layer during interconnect formation on Si devices. Another CAMP project involves the development of an electropolishing method for copper planarization during Si device fabrication. Professor Suni is also involved in fundamental research supported by the National Science Foundation to develop new architectures, which are based on metallic nanowires, and new detection methods for biosensors.
CAMP Professor Vladimir Privman, of Clarkson University's Departments of Physics and of Electrical and Computer Engineering, is the Director of the NSF-funded Center for Quantum Device Technology. He is exploring implications of quantum physics for future nanotechnology and information processing. He has also contributed to theories of uniform fine particles. Professor Privman's main contributions have been in developing and evaluating approaches to utilize semiconductor heterostructures and quantum wells, based on the silicon-chip device technology, for quantum information processing (quantum computing) and spintronics. He has also worked in modeling electron transport of relevance to single-quantum measurement and control.
Professor Ming-Cheng Cheng and some of his graduate students (Feixia Yu, Jun Lin and Bo Xu) have been developing efficient thermal models and circuits for the SOI devices and interconnects to take into account self-heating effects in SOI chips. These efficient thermal models and circuits greatly improve the accuracy of the existing thermal circuit used in the SOI industry for electro-thermal simulation of integrated circuits. The models/circuits will provide useful tools for modeling, characterization, optimization and reliability prediction of SOI devices and integrated circuits. Also, in collaboration with Professor Privman, Professor Cheng is working with his Ph.D. student Min Shen and Dr. Semion Saykin (of the Center for Quantum Device Technology) to study spin-polarized transport in semiconductor spintronic devices. The goal of this project is to develop transport models at different levels of efficiency and accuracy for modeling and optimization of semiconductor spintronic devices.
Professor Greg Campbell, director of CAMP's Extrusion and Mixing Consortium, continues to develop a more descriptive analysis for screw pumps, augers, and extruders. Over the past year much of his group's effort has been focused on the conveying of particular solids with these devices. In addition, his group is working to understand structure development in concentrated two phase systems. They found that bimodal dispersions act quite differently from single particle size systems. Also they have an actual program focused on understanding the reactions and physical changes that occur in an epoxy which forms liquid crystalline structures.
There is a growing interest in the measurement of the number concentration of submicron and ultra-fine particles both in the environment and in various industrial settings. CAMP Professor Philip Hopke, the Bayard D. Clarkson Distinguished Professor, and his group are very involved in this work. One of the major hypotheses that has been proposed to explain the adverse health effects of ambient airborne particulate matter is that ultra-fine particles that are present in high number concentrations are the responsible agents. In this case, particle mass that is the currently measured quantity may not be the best indicator of potential adverse consequences. Thus particle number concentration measurements are needed to test this hypothesis. In addition, there are a variety of particle counting needs in industrial settings. With the increased emphasis on nanometer sized particles, particle counters can be important in process control. There is currently only a limited number of instruments available to make such measurements. At Clarkson University, Professor Hopke and his group have been exploring heterogeneous nucleation with a turbulent mixing condensation nuclei counter (TMCNC) with support from the Environmental Protection Agency. Although the concept of a TMCNC has been available for over 15 years, it has been underutilized and could provide an instrument capable of particle detection down to 2 nm and could be developed into a viable commercial instrument. Clarkson University and Rupprecht and Patashnick, Inc., a leading manufacturer of airborne particle monitoring instruments, are developing this instrument into a functional, stand-alone particle counting prototype system that could then be the basis for a commercial product.