September 2004
American Institute of Physics
Smart lights, nonstick implants and 100th birthday of electronics at science & technology meetingSeptember 27, 2004--New York, NY--The AVS Science & Technology Society will hold its 51st International Symposium & Exhibition on November 14-19, 2004 in Anaheim, CA. Taking place during the 100th birthday of electronics, the Symposium will feature over 1400 papers and posters, with at least 2500 expected attendees.
SUMMARY
Some news highlights include: a 100th birthday celebration for electronics; new techniques for preventing troublesome sticking of proteins to life-saving medical implants; an important advance in tri-color LEDs, which might eventually replace ordinary white lights as a dramatically more energy-efficient light source; a chemistry-based method of using existing and less-expensive semiconductor technology to make a crucial component for future-generation computer chips; insights on why complex "quasicrystals" have less friction than ordinary crystals; and a possible new world record for survival of living cells in a microscopic, underwater obstacle course.
HOW TO COVER THE MEETING
The AVS Symposium Web Pressroom (http://www2.avs.org/symposium/anaheim/pressroom.html) contains links to the meeting press releases, additional story tips, and detailed lay-language versions of selected papers. For even more detail, the AVS Symposium home page (http://www2.avs.org/symposium/anaheim/default.asp) contains links to the full program as well as other meeting information.
The AVS Pressroom will be located in Room 212A of the Anaheim Convention Center. The room will be open on Monday-Thursday, November 15-18, 2004, from 8 a.m. to 5 p.m. The pressroom phone number will be 714-765-2030. Reporters can fill out a form to receive a complimentary registration badge by visiting http://www2.avs.org/symposium/anaheim/pressroom.html. Please make your request for a registration badge by November 5, 2004 if possible.
Even if you can't make it to Anaheim, the website's detailed information for reporters (http://www2.avs.org/symposium/anaheim/pressroom.html) is designed to enable you to cover meeting highlights from your desk. For assistance in contacting researchers and setting up interviews, please do not hesitate to contact the AIP and AVS staff listed at the top of the news release.
AVS--NOT JUST ABOUT VACUUM SCIENCE ANYMORE
Originally known as the American Vacuum Society, AVS was created in the 1950s as a forum to discuss problems and applications of high-vacuum technology, the process of making pristine environments almost completely devoid of air and other gases. Today, AVS papers showcase experiments not only in vacuums but also in many other "controlled environments."
These controlled environments include so-called "underwater surfaces," or carefully prepared samples immersed in liquids, which are the natural environment for many biological structures. In addition, AVS members study and manipulate the boundaries or "interfaces" between liquids and solids to make state-of-the-art fuel cells and better batteries.
Crucial processes for making computer chips, such as chemical vapor deposition, are now being done at atmospheric pressure where vacuum pressure was once necessary. Add to the list atomic- and molecular-scale microscopy, which is routinely done in air and liquid, and you'll get a sense of the many controlled environments that AVS members create and study for a whole host of applications over the entire spectrum of science and technology.
HIGHLIGHTS
Here is a sampling of some of the many intriguing talks that will be presented at the symposium.
I. SMART LIGHTS
II. SOLVING STICKINESS IN HEART IMPLANTS
III. 100TH ANNIVERSARY OF ELECTRONICS
IV. CHEMICAL "DEFECT ENGINEERING"
V. NOVEL QUASICRYSTAL FRICTION PROPERTIES VI. MODULATING THE CELLULAR ENVIRONMENT
VII. IRON DOTS FOR RELIABLE DATA STORAGE
VIII. ENZYMES ON SWITCHABLE SURFACES
I. SMART LIGHTS
Fred Schubert of Rensselaer Polytechnic Institute ([email protected]) will present a new light-emitting-diode (LED) structure, incorporating what is called a "high-reflectivity omni-directional reflector." The new reflector, made of three layers (a semiconductor, a dielectric and a metal) loses five times less light than a reflector made solely of metal. Schubert also reports that green, red and blue LEDs combined have the potential to be about 20% more efficient than the traditional phosphorus-based white LEDs currently in use. Schubert's tri-chromatic lights are twice as efficient as incandescent lights (32 lumens/watt, compared to 16 lumens/watt) and could be made four times as efficient. "We will see a huge transformation in the field of lighting, including the availability of smart lights which will be able to adapt to certain requirements and environments," Schubert said. "I expect great advances from this field." (Paper WL-WEM9, Wednesday, November 17, 2004, 11:00 AM, Room 304B)
II. SOLVING STICKINESS IN HEART IMPLANTS
Proteins tend to stick to surfaces. In the case of a medical stent or heart implant, the protein fibrinogen, which initiates clotting, sticks to the surface of the plastic implant. Then fibrinogen attracts platelets, which continue the clotting process and can clog up the implant. So one way to stop the clotting, reported by Thomas Horbett of the University of Washington in Seattle ([email protected]) is to stop the fibrinogen from attracting platelets. Sometimes, the surfaces of the implant will adsorb the fibrinogen in a form in which it does not attract the platelets, but it's not yet known why, making it hard to design a surface to do that on purpose. Horbett will also report on another method that is easier to incorporate into the design of a surface: having the surface repel the fibrinogen. His team has tested adding a very water-soluble and water-attracting polymer, polyethylene oxide, to the polyurethanes that could make up an implantable object, or coating surfaces with a polymer that acts like polyethylene oxide. (Paper BI-MoA6, Monday, November 15, 2004, 3:40 PM, Room 210D)
III. 100TH ANNIVERSARY OF ELECTRONICS
November 16 marks the 100th birthday of electronics, which began with British scientist John Ambrose Fleming's 1904 invention of the first practical electronic device. Known as the thermionic diode, this first simple vacuum tube, containing only two electrodes, could be used to convert an alternating current (ac) to a direct current (dc). A special AVS session, taking place exactly 100 years after the day that Fleming applied for a British patent on the diode, will celebrate this seminal invention and the subsequent evolution of electronic components based on vacuum devices.
Fred Dylla of Jefferson Lab in Virginia ([email protected]) will open the session by describing Fleming's invention and its connection to Thomson's late-19th century discovery of the electron and Edison's invention of the incandescent lamp. Paul Redhead of the National Research Council in Canada ([email protected]) traces both the rise and fall of the first electronics industry, based on the manufacture of vacuum tubes for radio, television and radar in the first half of the 20th century, and the vacuum technology used in electron tube manufacture. The vacuum tubes of this bygone, pre-transistor electronics age, and the current generation of vacuum tubes for displays and high-power microwave generators, would not be reliable devices without the invention and industrialization of miniature vacuum pumps that can be installed within a tube's internal volume.
These "getter" pumps are described by Bruno Ferrario (SAES Getters, Lianate, Italy; [email protected]), who has been involved with both the basic research on their operation and the applied research to optimize their fabrication. The session's final talk will be given by Gary McGuire of the International Technology Center in North Carolina ([email protected]), who will describe how, over the last 25 years, the vacuum tube and modern microelectronics have merged. These technologies have been combined for specialized devices termed "vacuum microelectronics," which combine the attributes of both technologies: the ease of control of an electron beam in vacuum with the miniaturization and mass-production capabilities of integrated circuit production. (Tuesday, November 16, 2004, 1:20 PM- 4:00 PM, Room 303D)
IV. CHEMICAL "DEFECT ENGINEERING"
Eliminating a major roadblock to future-generation silicon chips, researchers have demonstrated an approach to reliably make small-scale versions of a pn junction, the crucial region of a semiconductor that changes from electron-rich (the "n" zone) to electron-poor (the "p" zone). Today, pn junctions are only 25 nanometers (100 atoms) deep. But to make increasingly smaller (and faster) silicon chips, the International Technology Roadmap for Semiconductors dictates that by 2010 the pn junctions must have depths of 10 nanometers, or just 40 atoms.
The conventional method for making the junctions is called "ion implantation," in which charged versions of a foreign atom ("dopant") are accelerated into a silicon wafer to create electrically active regions that are either electron-rich or electron-poor. Unfortunately, current ion-implantation methods cannot make 10-nm-deep pn junctions without inadvertently moving silicon atoms into some of the spots intended for dopants.
Now, University of Illinois researchers (Edmund Seebauer, [email protected]) are using surface chemistry to come to the rescue. In computer simulations, they showed how removing surface layers such as silicon dioxide frees up the dangling bonds. Silicon atoms then preferentially rise to the surface while tending to leave the dopant atoms in place. Verified in subsequent experiments, this idea for "defect engineering" has been shown to be a feasible solution for using traditional ion-implantation technology to make smaller-scale silicon-based electronic devices. (Paper EM-TuA7, Tuesday, November 16, 2004, 3:20 PM, Room 304B.)
[Lay-language version of meeting paper at http://www2.avs.org/symposium/anaheim/pressroom/seebauer.pdf ]
V. NOVEL QUASICRYSTAL FRICTION PROPERTIES
Quasicrystals, solid materials whose atoms arrange themselves in five- or 10-sided building blocks (providing what's called five- or 10-fold symmetry) and then form 12-sided (dodecahedral) grains, seem to exhibit less friction than do many other materials. Quasicrystals' highly complex atomic patterns are partly repeating (periodic) and partly nonrepeating (aperiodic). For the past ten years no explanation for their reduced friction has been found. Does it arise from some macroscopic cause---hardness or surface chemistry, say---or from some fundamental property related to the exotic quasicrystal structure? J.Y. Park and his colleagues at Lawrence Berkeley Laboratory and Ames Laboratory have looked at this issue by dragging a probe microscope across a sample. What Park found was a highly anisotropic friction for his Al-Ni-Co quasicrystal: low friction when sliding the probe in the aperiodic direction and high friction when sliding along the periodic direction ([email protected], see website at http://stm.lbl.gov/research/Quasicrystal/Quasicrystal.html). (Paper NS-WeA9, Wednesday, November 17, 2004, 4:40 PM, Room 213D)
[Lay-language version of meeting paper at http://www2.avs.org/symposium/anaheim/pressroom/park.pdf ]
VI. MODULATING THE CELLULAR ENVIRONMENT
on a very small scale is possible with microfluidic devices (runways and mixing volumes etched onto a chip) using only a few ports and directed fluid streams passing over patterned culture media. Albert Folch of the University of Washington ([email protected]) and graduate student Anna Tourovskaia will report on the successful solution of certain microfluidic problems, such as keeping cells alive---their lab might hold the record at two weeks---and controlling fluid delivery to such a degree that entire cell analysis can be performed within the microfluidic channels. With this "complete cell culture lab on a chip" in hand, Folch believes that microfluidic technology is now ready for complex cell-based experimentation (see website at faculty.washington.edu/afolch). (Paper BI+MN-FrM8, Friday, November 19, 2004, 10:40 AM, Room 210D)
VII. IRON DOTS FOR RELIABLE DATA STORAGE
To cram more data storage into computer hard drives, manufacturers continually reduce the size of magnetic bits, the little regions of magnetic material that register 0s and 1s of computer data. In a typical 100 GB drive, the bit size is 160 nanometers wide by 41 nanometers long. However, when the bits in traditional hard-drive designs become smaller than a few tens of nanometers, they will become unstable and flip back and forth between 0 and 1 values at room temperature. This is known as the "superparamagnetic" limit and researchers need to develop new technologies for magnetic data storage. Towards these ends, an Oak Ridge-University of Tennessee team (Maria Torija, [email protected], E.W. Plummer and J. Shen) has built an assembly of iron dots, each no more than a few nanometers across, which are magnetic. They have found that a magnetic interaction between the dots and their surroundings dramatically enhances the stability of the dots' magnetic properties. Their experimental data appears to indicate that the stabilizing interaction occurs between the dots and the metal (copper) surface on which the dots lie. The researchers will continue studying what appears to be a stable platform for future data storage. (Paper MI-WeM5, Wednesday, November 17, 2004, 9:40 AM, Room 304A)
[Lay-language version of meeting paper at http://www2.avs.org/symposium/anaheim/pressroom/torija.pdf]
VIII. ENZYMES ON SWITCHABLE SURFACES
Most synthetic surfaces just sit passively while active compounds flow around them. But what if a surface could respond, too, depending on what it's covered with? A group at the University of Manchester, headed by Rein Ulijn ([email protected]), have been working on using proteases as keys to unlock surfaces. Proteases, such as chymotrypsin, the one Ulijn is studying, break open proteins and peptides. In some cases, breaking a protein changes its properties, just as an open door no longer keeps out the wind. If you want fresh air, that can be a good thing. So Ulijn's group covers a glass surface with peptides that only can be unlocked by certain proteases. So, for instance, a disease-related enzyme could eventually be made to trigger a surface to release a drug. "The ability to switch surface properties by enzymes in the presence of cells also indicates that it may be possible to switch between bio-inert and bioactive surfaces �for instance, by presenting drugs or growth factors on demand," Ulijn said. (Paper BIFrM3, Friday 9:00 AM, Room 210D)
ADDITIONAL STORY TIPS
For more information, visit the online pressroom at http://www2.avs.org/symposium/anaheim/pressroom.html
Contact: Ben Stein, 301-209-3091, [email protected], Phillip Schewe, 301-209-3092, [email protected], Martha Heil, 301-209-3088, [email protected] at the American Institute of Physics, and Della Miller, 530-896-0477, [email protected], 714-765-2030 from 11/15-11/18, AVS West Business Office
More story tips, on topics ranging from exotic "half-metals" to recently discovered "chemicurrents" on surfaces can be found at http://www2.avs.org/symposium/anaheim/pressroom/tips.pdf.
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