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News and Highlights Tutorials
Traditionally, the tutorials kickoff the MRS Fall and Spring Meetings. The 2004 Fall Meeting commenced on Sunday in Boston with five tutorials held during the day, all in the afternoon. The topics were varied and included semiconductor sensors, nanomagnetic structures, micro-/nanotechnology in regenerative medicine, organic nanophotonics and Demoworks - the fine art of materials science demonstrations. MRS was pleased to learn that the Mayor of Boston has proclaimed Monday, November 29, as MATERIALS SCIENCE DAY in the city in honor of the MRS Fall Meeting.
Paras N. Prasad and Alexander Cartwright (both from University of Buffalo) alternated on stage to cover organic nanophotonics in Tutorial DD on Sunday afternoon. First Prasad addressed what it means to talk of nanophotonics in the first place. Is it confinement of radiation? Is it confinement of matter? Or is it confinement of photoprocesses? It can be any of these. And in the case of light, nanoscale means on a scale smaller than the wavelength of the light involved, generally ranging from a few nanometers to hundreds of nanometers. At this scale, optical properties become size-dependent. That length can be the particle size, length of a “nanomer” (short polymer), domains, or composite components.
The tutorial then went deeper into the understanding of the physics, characterization, and manifestations of various forms of confinement. In addition to altering the bandgap, dynamics can be affected. Prospects abound in areas such as lasers, chemical and biological sensors, and UV emitters. Organics, particularly hybrids (e.g. combining nanoparticles and polymers), offer opportunities and challenges by combining the benefits and detriments of both organic and inorganic materials.
Tutorial: New Approaches in the Design, Synthesis, and Integration of Semiconductor Sensors Sensors based on semiconductors are attracting significant attention due to their low cost and ability to be integrated in electronic devices. However, improvements in the sensors' properties are required, such as smaller size, better selectivity and sensitivity, and faster response, together with high device reliability, easy integration in electronic devices, and low production costs. Ted Kamins (Hewlett-Packard Laboratories) started the session with five crucial questions that need to be answered for sensors: What is being sensed, using what mechanisms, what is the form of the sensing structure, what materials are being used and what are the industry's needs? Kamins then systematically described various types of semiconductor sensors including photosensors and their fabrication, pressure sensors, temperature sensors, magnetic sensors, and gas/chemical/bio sensors. He also described sensors based on nanowires and nanotubes. Next, Johannes W. Schwank (Univ. Michigan) discussed materials developments and sensing mechanisms with a focus on gas sensing. He described the key issues and major current challenges in gas sensor development including engineering of well-defined sensor structures and pattern recognition methods. There are a number of important applications of gas sensors including oxygen sensing in automobiles to control air/fuel ratios, and monitoring and control of emissions of environmentally unfriendly gases. Schwank then discussed gas-solid interactions in sensors including the effects of catalysts and the sensing mechanisms. Finally, he described various tools and methods for the selection and optimization of gas sensor materials such as combinatorial synthesis and modeling.
Tutorial: Micro- and Nanotechnology in Regenerative Medicine This tutorial formed part of symposium AA on applications of nanoscale materials in biology and medicine, and was presented by Tejal Desai (Boston Univ.) and Edward A. Botchwey (Univ. Virginia).It provided an overview of recent advances in the design and utilization of micro- and nanoscale biomaterials in regenerative medicine. Topics covered included the use of bio-electromechanical systems (bioMEMS) to perform bioanalytical processes and to create templates for cell and tissue regeneration, micro- and nanofabrication methods for the design of tissue engineering scaffolds based on synthetic and natural polymeric materials, and the characterization of micro- and nanofabricated materials with a focus on the relationships between material structure and biological function. Desai started the symposium with a broad overview of tissue engineering (cells + supporting material + extracellular signals = biological substitute). She described the five therapies for missing organs: transplantation, autografting, permanent implants, in vitro synthesis and in vivo synthesis. She then described the three major strategies used thus far for the regeneration of new tissue which are the infusion of isolated cells, production and delivery of tissue-inducing substances, and cells placed on or within matrices. Desai then discussed the micro-/nanoscale in biology. She described various examples of tissue engineering such as the formation of 2-D and 3-D scaffolds. Next, Edward Botchwey continued with the design of micro and nanoscale materials for the purposes of regenerative medicine. He described various micro/nano contact printing techniques, including current challenges and ongoing work in various laboratories. He then described new biomaterials for nanofiber-based scaffolds, in particular the polyphosphazene family of polymers which are ideal because of the unusual flexibility of the -P-N- backbone, tailoring of properties using different side groups, and high compatibility with blood and tissue. Botchwey described various possible biomedical applications such as drug delivery matrices, wound dressings, and vascular grafts. He discussed in detail microsphere-based scaffolds for tissue engineering including bone, micro-sphere based polymer-ceramic constructs, and microsphere scaffolds for bioreactor-based tissue engineering.
Tutorial: Demoworks - Materials Science Demonstrations In a tutorial for Symposium PP on materials education, Anissa Ramirez ( Yale Univ.) and Amy Moll (Boise State Univ.) led a hands-on workshop of materials science demonstrations designed for students in a college-level Introduction to Materials class. The purpose of their “Module Workshop” was to display the benefits of “active learning.” In defining learning styles, Moll said that instructors cannot do much about students’ abilities, backgrounds, or learning styles, all of which affect how students learn, but instructors can modify their teaching style. Studies show that lectures tend to be the least effective way for students to learn as the attention span of the average adult is 15 minutes! In order to help with the learning process, Ramirez pulled together a book of materials activities for instructors and students to do in the classroom. By engaging with materials “toys,” followed by explanations and discussion of the activities, students will store what they’ve learned in long-term memory. At the tutorial, Ramirez and Moll set up six tables, each containing 2–3 activities, including demonstrations on diffraction, ferrofluids, and amorphous metals. At one table, for example, participants created electromagnets by connecting a nail to a C-battery via tiny loops of wire around the nail, which magnetized the paramagnet. After playing with the toys, the participants regrouped and shared other activities they’ve done in classrooms. Destructive demonstrations seem to generate the most enthusiasm!
A special program for high school science teachers was organized and over 90 teachers from various parts of the United States participated. They attended special demonstrations and sessions at the Museum of Science in conjunction with the Strange Matter exhibit. They also attended the tutorial on high school materials science demonstrations. In the evening, they were part of the special President's reception at the Museum of Science to celebrate the Strange Matter exhibit. The teachers will be able to attend talks and other events throughout the week at the Fall Meeting. The program was funded by NSF and Raytheon.
© Materials Research Society, 2004
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