|U.S. Navy personnel prepare to deploy one of the advanced ORNL-developed acoustic monitoring systems off the bow of the USNS Hayes. The latticework of hydrophones is strung above pressure vessels containing instruments.|
e have devised instruments to measure or monitor radiation levels, electromagnetic fields, temperatures, sounds, and the weight of gases. We have conducted testing to hasten the commercialization of new manufacturing technologies. We have created methods to control a variety of systems. The capabilities represented by this core competency span the range from basic research in materials and processes through prototype development to production-scale facilities for precision manufacturing and inspection at the Oak Ridge Centers for Manufacturing Technology.
Because of our skills in measurement science, we have developed miniature, automated sensors that measure barely detectable quantities. By integrating these sensors with electronics and computing capabilities, we have developed early warning systems and advanced control technologies. Thanks to our instrumentation and control expertise, we received two R&D 100 awards in 1995 in this areaone for a gravimetric gas flow calibrator (that calibrates gas flow meters) and the other for a magnetic spectral receiver (that monitors magnetic fields that may degrade the performance of power plant control instruments).
Oak Ridge's strength in manufacturing technologies reflects a unique three-site collaboration involving ORNL and the Oak Ridge Y-12 Plant and K-25 Site. Within this partnership, ORNL's research and development capabilities in materials and processes are meshed with the precision manufacturing, fabrication, and inspection skills of Y-12 Plant personnel and with state-of-the-art pollution prevention technologies at the K-25 Site.
ORNL Measures the Undetectable:
To better escape detection as they ply the seas, American submarines are becoming quieter. So, before sending its new subs out to sea, how does the U.S. Navy know if its latest immersed stealth technology is as quiet as it's designed to be and otherwise operates as specified? The Navy has obtained its answers from the world's most advanced underwater acoustic measurement system, developed by ORNL. This system, which detects the equivalent of whispers in a noisy crowd, precisely measures acoustic images, or signatures, of noise radiated from U.S. submarines. It provides acoustic measurements of energies that are normally undetectable because their level is below the ocean's background noise.
By combining our expertise in computing, instrumentation, and system integration, we have designed and built electronic devices and developed signal processing technologies that provide accurate measurement of sounds so small they would otherwise be undetectable. We have met Navy requirements to qualify the operating characteristics and specifications of the newest U.S. submarinesthe SSN 21 Seawolf and the next-generation submarines planned for production in the next 10 years. Our system ensures that acoustic emissions from these vessels are kept at levels below their design limits. The Navy's ability to maintain stealth in the U.S. submarine fleet depends largely on ORNL's ability to measure the sound of silence.
Funding for ORNL's development work in the Acoustic Measurement Facilities Improvement Program was provided by the U.S. Navy, Naval Surface Warfare Center, Carderock Division.
Lab on a Chip Analyzes DNA in a Droplet
|This "lab on a chip" has been used to analyze DNA.|
|Mike Ramsey shows the MicroBioLab chip developed at ORNL. Photograph by John Smith.|
We know one way to shrink a chemistry laboratory: build a "lab on a chip." We have developed a postage stamp-size MicroBioLab chip that can dissect DNA in a droplet. Compared with today's commercial analytical instruments, it works 10 times faster, analyzing DNA in only 5 minutes instead of an hour. Also, it can chemically analyze a liquid sample 10,000 times smaller, saving materials. In addition, less labor is required because it's computer controlled.
Such a cost-effective, time-saving chip could be built for genetic diagnosis, DNA fingerprinting, and drug research. It could screen for people carrying genes that predispose them to developing breast cancer, becoming obese, or having children with cystic fibrosis. To make such an analysis, it is hoped that only a few blood or skin cells in a drop would be required.
The technology could also have forensic uses such as DNA fingerprintinga technique for comparing molecular characteristics of blood at the crime scene with those of blood from victims and suspects. One person could collect blood samples at the scene of the crime and do an analysis then, reducing the chance of contamination by other people's blood.
Another possible use is in drug research. Because enzyme-inhibiting chemicals are expensive and hard to come by, drug companies are interested in technologies for analyzing very small samples to find potentially effective drugs.
Thin as a microscope slide, our glass microchip has been etched to form interconnected chambers and channels, just beneath the surface. Charged molecules in a tiny liquid sample are mixed in a chamber and "pumped" through hairlike channels by an applied electrical field. The molecules glide around the hairpin turns of a winding capillary channel, covering an area the size of the face of a wrist watch.
Before DNA moleculescut into fragments by enzymesenter a separation channel where they are separated by size and electric charge, they react with a fluorescent dye. The dye causes the fragments to give off light when a laser beam is shone on them just below the separation channel; the larger the separated fragment, the stronger the fluorescence. The detected light intensities are fed to a computer, which sorts through signals from separated fragments to provide a sample analysis. MicroBioLab chips may be small, but the potential is large.
The research was supported by DOE through ORNL's Laboratory Directed Research and Development Fund.
Microcantilevers: Sensors with Sensitivity
Thanks to a problem with a high-tech microscope, ORNL researchers have developed microscopic sensorshairlike, silicon-based devices that are at least 1000 times more sensitive and 1000 times smaller than currently used sensors. They can detect and measure relative humidity, temperature, pressure, flow, viscosity, sound, natural gas, mercury vapor, and ultraviolet and infrared radiation. They also show potential as biosensorsdevices that can detect DNA sequences and proteins.
|Taking a break from his work with an atomic-force microscope, Thomas Thundat observes the magnification of a straight pin, an insect, and an ORNL-developed cantilever sensor, like the one he's holding. By comparison, the cantilever sensor is the smallest of all. These microscopic sensors can be used to measure heat, sound, water and gas concentrations, and radiation.|
Microcantilevers of silicon or silicon nitride have been made that are smaller than the period at the end of this sentence. These "microscopic diving boards" project from miniature chips about the size of a grain of rice.
ORNL researchers have shown that a microcantilever would bend in a measurable way if its tip is coated with a material that attracts another material from the air. For example, a gold-coated cantilever absorbs mercury vapor, which stiffens the cantilever, causing it to bend and changing the way it vibrates. A gelatin tip absorbs water, measuring humidity. A silicon microcantilever coated with aluminum bends more with rising temperature because aluminum expands more than silicon. Such a device can measure temperature and even detect infrared radiation and heat-generating chemical reactions. When set in motion, microcantilevers have a natural vibration that changes in the presence of sound waves or a fluid (enabling measurements of viscosity and pressure).
Changes in cantilever position or vibration rate can be detected by measuring wobble in reflected laser beams. Future silicon devices, however, will probably be based on piezoresistancechanges in electrical resistance induced by increased bending or reduced vibration. One of our patented technologies has been licensed to Consultec, Inc., which has fabricated a prototype mercury vapor sensor and an infrared thermometer. Thanks to a problem, ORNL devised a new class of sensors that may help industry find economical solutions.
DOE's Office of Health and Environmental Research funded this work.
Neutron Technique May Help Coal, Cement Industries
|ORNL's nonintrusive inspection technique that uses neutrons can detect cocaine in pallets of sugar.|
A nonintrusive inspection technique that probes samples with neutrons can analyze the content of coal and cement and detect explosives and drugs. It also shows promise for locating plastic and wooden land mines.
Developed by ORNL and Western Kentucky University (WKU) researchers, the pulsed fast-thermal neutron analysis system bombards a sample with pulses of fast and slow, or thermal, neutrons. Fast neutrons collide with some atomic nuclei, triggering the release of gamma rays. Between pulses, thermal neutrons are captured by other nuclei, resulting in emission of gamma rays. Detectors measure energies of the combined gamma rays, which are unique for each element.
Gamma-ray fingerprints permit accurate determinations of concentrations of hydrogen, carbon, oxygen, nitrogen, chlorine, sulfur, and other elements in samples. Using both fast and slow neutrons allows detection of more common elements. For example, carbon can be readily identified using fast, but not slow, neutrons; the reverse is true for chlorine. The new technique's power lies in its ability to measure elemental content on-line during industrial operations.
Negotiations are under way to install a prototype pulsed-neutron generator system at an operating coal-fired power plant. The coal industry has a strong need for this on-line analytical capability. To price coal accurately or blend it to make it cleaner, it helps to know its sulfur content. To operate a coal power plant as efficiently as possible, it is important to know how much carbon and oxygen are in the coal. To cut back deposits that clog pipes in boilers, it is wise to burn coal low in chlorine. Because chlorine is a "poison" in crystallization of cement, manufacturers of cement have expressed a desire for an on-line analytical capability for quality and process control.
The neutron generation system shows promise for other applications. WKU researchers have demonstrated the technique's ability to distinguish between actual and mock explosives in munitions shells in military proving grounds to speed up environmental restoration and to inspect pallets of rice, sugar, or coffee for cocaine. ORNL researchers are investigating whether the technique can guide the safe removal of land mines.
The research has been sponsored by DOE's Experimental Program to Stimulate Cooperative Research.
Electron Beams May Cure Plastics Problem
|ORNL conducts experiments in producing polymer- composite parts using a continuously operated electron-beam system in western Canada. The electron beam scan horn at top center directs and controls distribution of electrons to composite test parts.|
The problem with PMCs lies in the high cost to manufacture them. Currently, the high-strength plastic is formed from fibers held together by polymers, compounds of high molecular weight that have millions of repeated linked unitseach a relatively simple and light molecule. To cure the composite, chains of polymers mixed with fibers must be linked by creating covalent chemical bonds in which electrons are shared. This cross-linking is achieved today by thermal curing using gas-fired ovens or steam-operated autoclaves. Thermal curing uses considerable energy to heat and cool the material, is time consuming, and can induce residual stresses in the finished part. It also requires use of a hardener, which can be a source of potentially toxic emissions.
An alternative curing process that uses less energy, requires minutes rather than hours, emits no pollutants, and is potentially less costly is now being investigated in Oak Ridge. ORNL researchers are leading a national effort to advance and commercialize a PMC curing technology that would use nonthermal electron beams from a high-energy accelerator. This technology is now used for coatings and sterilization of foods and medical supplies. Participants include researchers at the Oak Ridge Centers for Manufacturing Technology, DOE's Sandia National Laboratories, and 10 industrial partners involved in a cooperative research and development agreement (CRADA) supported by DOE.
The goal is to develop electron-beam technology that can produce better products in higher volumes than are generated by thermal curing and at lower costs. By comparison, electron-beam curing has the potential to reduce tooling and manufacturing costs and curing times; simplify processing; improve part quality; and make unique products not producible in any other way. The process is also environmentally friendly: hardeners are not required in the resin, and no volatile substances in the resin escape to the atmosphere because of the low cure temperatures and the material's composition.
ORNL researchers played an important role in developing new chemistry to inexpensively modify the PMC base-resin material, rendering it curable by electron beams. They identified a group of photoinitiators that enables the material to be cured under a range of temperature conditions. The photoinitiators allow electron beams to ionize the polymer chains so cross-linking occurs. The patented process has been licensed to two manufacturers of resin systems.
Results of the CRADA so far indicate the concept is technically and economically viable. Four independent economic studies confirm a 50% reduction in manufacturing cost. Continued success with this project should provide the plastics industry with the stimulus to produce affordable composites for a broad range of uses by the transportation industry.
RF System May Improve Chip Production
As prices of computer chips fall and costs of chip processing equipment rise, the U.S. semiconductor industry seeks to become more competitive. Its goals are to pack more circuits onto semiconductor wafers and produce more high-quality wafers per day. One approach to achieving these goals is to get better control over plasma etching of wafers. In this process, hot ionized molecules, such as a gaseous compound of fluorine, etch integrated circuit patterns many times smaller than a human hair.
|ORNL's Tony Moore (in white shirt) points out features of the rf matcher invented at the Laboratory. The small device at the back of the table is an ORNL-developed sensor for the rf system for accurately measuring and controlling rf power levels in plasma processing equipment used to produce semiconductor chips. Photograph by Steve Eberhardt.|
Sometimes the plasma is not well controlled because of fluctuations in radiofrequency (rf) power levels that result in variations from wafer to wafer. If these variations are large enough, wafers can be defective.
One of the keys to producing a uniform etch is accurately controlling the rf power that generates the plasma. The rf energy is used to break down the gas and ionize the etch gaseous compound. Then neutral atoms fall out of the plasma onto the wafer, etching the surface chemically.
Under a CRADA between DOE and SEMATECH, ORNL researchers have developed a technique for accurately measuring and controlling rf power levels in plasma-processing equipment. The rf system controls delivered power to plasmas at least 10 times faster and more accurately than systems routinely used throughout the industry. This novel system offers the potential for improved yield and increased throughput of high-quality wafers from plasma etch equipment.
The measurement technique uses two highly nonobtrusive sensors (invented by ORNL researchers) that determine whether the impedance (resistance and capacitive reactance) in the plasma and the rf generator match. The sensors take data on impedance mismatches in equipment and cables that carry the rf power and feed it to a microprocessor that controls a novel electronic rf power matching network that has no moving parts (invented by ORNL).
In a few milliseconds, the controller tunes the rf matcher so that rf impedance matches the changing electrical impedance of the plasma in the etch equipment. The controller also rapidly adjusts the rf power level of the generator to compensate for power losses along the delivery path to maintain constant delivered power to the plasma. The combination of accurate sensing and rapid controlling of rf power offers better plasma control, fewer wafer-to-wafer variations, and increased production throughputs with higher yields.
Through better control of plasma etching, the U.S. semiconductor industry can improve its competitiveness in the world market.
Optics Testing Technology Now Affordable
|Curt Maxey aligns the CGH Null Adapter using a specialized computer-generated hologram. In conjunction with custom CGH null lenses, the product enables aspheric optics to be tested with conventional interferometers to ensure they have the right shape. Photograph by Lynn Freeny.|
The optics industry is focused on finding cost-effective technologies for producing better, smaller, and lighter optical devices. The industry also seeks to avoid the types of errors that gave the Hubble Space Telescope blurry vision and to embrace the technology that ensured its correction.
Although mirrors and lenses with spherical surfaces are relatively easy to manufacture and test, optics manufacturers are increasing production of optical components that have not quite spherical, or aspheric, surfaces (as in the space telescope's parabolic mirror). Although aspheres have been produced for centuries, technology for manufacturing them has significantly improved only in recent years. Use of aspheric components significantly reduces the number of optical elements required, making possible lighter, smaller optical packages.
Traditionally, optics manufacturers machine-ground telescope mirrors to about the right shape. To get a smooth enough curved surface to capture and focus light, opticians would hand-polish the mirror. Nowadays, an increasing number of optical components are formed and polished by computer-controlled processes. Single-point diamond turning is now routinely used to rapidly produce precision aspheric optics in metals, plastics, and selected crystalline materials. Unfortunately, testing technology has lagged behind precision manufacturing, contributing to the high cost.
To determine if an aspheric lens or mirror has the right shape, an optical measuring system is used. Light from a laser is bounced off the optic and back through an interferometer, forming an interference pattern. Conventional null lenses bend the light from the interferometer into a shape that matches the aspheric optic. These patterns are imaged and analyzed to determine if and where the optic requires more polishing. Because the accuracy of a conventional null lens depends on alignment of individual lens elements, it can give erroneous results if assembled with an error in spacing. Such a null lens deficiency resulted in the wrongly shaped mirror in the Hubble Space Telescope.
Much of the uncertainty in testing aspheric optics has been removed by the development of computer-generated holograms (CGH). Using diffraction, the phenomenon that produces the rainbow of colors in a compact disc, a CGH null lens bends light to match the shape of an aspheric optic. CGH technology is now considered the most reliable in the world for testing aspheric optics. CGH lenses were used to certify the accuracy of aspheric optics that were later installed during a space mission to correct the vision of the Hubble Space Telescope.
Because of the complexity of CGH technology, only a few specialized optical manufacturers could afford it. Now, thanks to a CRADA between ORNL and Diffraction International of Minnesota, reliable CGH technology is now affordable and available for all optics manufacturers. Diffraction International's revolutionary product, the CGH Null Adapter, is a simple accessory that allows accurate testing of aspheric optical surfaces using standard commercially available test equipment. Significantly, the product cuts the cost of the technology about 90%, from more than $100,000 to $10,000.
To hasten the commercialization of the CGH Null Adapter, ORNL metrologists tested early prototypes and provided detailed feedback to Diffraction International on the product's performance. Through a series of tests with different aspheric optics and measurement systems, the CGH Null Adapter evolved to its current form. Now, it's catching the eye of the cost-conscious optics industry.
The CRADA was funded by the DOE Energy Research Laboratory Technology Applications Program.
ORNL Boosts Police Security for Olympics
"Security for the Atlanta Olympics should be the best in modern history, thanks in part to the fusion of computer, communications, and police sciences at a level never before attempted." So said General Barry McCaffrey, director of the White House Office of National Drug Control Policy. The advanced technology package, called the Police Command and Control System, was developed for his Counterdrug Technology Assessment Center by ORNL. It was part of the Clinton administration's plan to fight drugs and crime in the Atlanta area during the 1996 Summer Olympic Games.
|Bob Hunter checks the computer display showing the buildings (pink blocks) and streets (red lines) of Atlanta and Olympic Games venues (yellow and green spots). ORNL's computer system helped coordinate the relocation of police officers in response to emergencies. Photograph by Tom Cerniglio. Photograph by Lynn Freeny.|
This command, control, and scheduling system provided information vital to the creation of future systems for use by local, state, and federal law enforcement agencies. During the Olympics, the system gave the Atlanta Police Department a critical response advantage as it exercised responsibility for security during the games.
The Atlanta Police Department, which worked directly with ORNL to develop the computer system, gave the system good reviews. The pioneering Police Command and Control System, says the department's Major Jon Gordon, "gives real-time knowledge of and maximum access to every security resource available to meet a wide variety of potential problems, challenges, and instant crises. During the Olympics, these ranged from vehicular traffic gridlock miles from the events to possible criminal activity at one or more of the games' venues."
The ORNL team specializes in redefining problems normally solved on expensive workstations so they can be handled by low-cost, easy-to-use PCs. Use of PCs significantly reduced training and maintenance requirements for the Atlanta Police.
The chief of police used the system's "central manager" computer to analyze ongoing situations during the Olympics to assist in making critical decisions on police deployment. For example, when a pipe bomb went off in Centennial Olympic Park, the system provided an immediate assessment of the situation. As a result, the police chief could close the minimum number of streets to cordon off the area and direct police personnel to the scene to provide public safety support. Should a situation have required moving police forces to address security problems at a new location, the central manager could have automatically scheduled the relocation of nearly 2000 police and minimized the impact on other venues.
Most of the data (e.g, breakdown of a squad car, excessive traffic congestion, people injured in an accident) were communicated to the central manager system from police using other computers in the Olympic ringthe "field manager systems." The command-and-control system can also be used for complex analysis of patterns of crime from tens of thousands of pieces of information.
This project was supported by the White House Office of National Drug Control Policy.