Research Spotlights
Prof. Gregory Raupp Leads ASU’s Flexible Display Center
Chemical Engineering Professor Gregory Raupp is the director of “Flexible Display Center” that is funded by the Army. The funding level is $43.7 millions for the first five years, with an option of $50 million for the next five years.
The Army funds this center because it is interested in battery-powered flexible displays for soldiers of the future to wear on a sleeve or carry in a pocket. There could be plenty of civilian uses too. Among the possibilities: T-shirts with moving images, home entertainment screens that morph into wallpaper or works of art when not in use, and displays in motor vehicle windshields. The center conducts cutting edge research in flexible display. Much of the technology being developed at the center is not available anywhere else in the world.
To produce the displays, the center is manufacturing thin film transistors that go behind each dot, or pixel, making up the display. The microscopic transistors serve as a switch, telling the pixels to be light or dark. An array of 80,000 pixels lined up in rows and columns creates an image the user sees in a manner similar to a conventional television or computer screen.
Membranes with Ordered Nanopores
Research conducted in Jerry Lin's lab is focused on advanced materials, in particular, membranes, adsorbents, and catalysts, for use in separation, reaction and alternative energy applications. One of the focus areas is ordered nanoporous membranes. These materials are prepared by a method known as liquid crystal tampelating (LCT). The LCT synthesis approach employs self assembled arrays of surfactant molecules as structure directing templates to make hexagonally ordered nanoporous silica materials. Dr. Lin and his colleagues have successfully synthesized nanoporous silica fibers by an interfacial LCT growth method and identified the factors that affect the growth of the fiber into this highly ordered hexagonal structure. Dr Lin’s group has made the first research effort to measure the gas diffusivity of the ordered nanoporous silica using the transient gravimetric approach that has provided improved insight into the microstructure of the ordered nanopores in the silica fibers.
Dr. Lin also collaborated with Dr. Zhu’s group in McMater University on use of this group of materials as catalysts for polymer synthesis. They have demonstrated the use of these hexagonally ordered nanotubes as molecular extruders for fabrication of extended-chain crystals of polyethylene fibers. These polyethylene fibers were obtained in one step and were seen to have structural and mechanical properties far better than those obtained by costly post-treatment conventional techniques.
The present research in Dr. Lin lab in this area focuses on making vertically oriented nanoporous membranes. These membranes are being synthesized by a novel counter diffusion self assembly method. Exciting preliminary results have been obtained by this approach to grow vertically oriented nanoporous membranes. These membranes once synthesized will find applications in separation, catalysis, bioreactor, sensors and electrochemical devices.
ASU Discovery May Aid Counter-Terrorism Efforts
The thwarted 2006 London airline bomb plot not only heightened summer travel fears and created new passenger screening inconveniences, but also greatly underscored the urgent need for improved national security measures.
Now, Professor Joe Wang, Director of the Center for Biosensors and Bioelectronics at the Biodesign Institute at Arizona State University, has developed a highly sensitive technology to rapidly detect liquid peroxide explosives in as little as 15 seconds. The results are published as a research communication online in this week’s edition of the leading international analytical journal, The Analyst.
“Previously, there have been no effective sensing technologies that can detect these compounds in a rapid and sensitive manner, so this is an important first step in trying to stay ahead of the terrorists who are becoming increasingly sophisticated in their methods,” said Wang, who serves as a faculty member with joint appointments in the Departments of Chemical Engineering in the Ira A. Fulton School of Engineering and Chemistry and Biochemistry in the College of Liberal Arts and Sciences.
In the past few years, terrorists have turned from high-grade commercial explosives toward improvised, homemade explosives that can be made from off-the-shelf products. Though prevented from use by the unraveling of the 2006 air travel plot, such devices were employed in the Madrid and London train bombings of 2004 and 2005, respectively.
Ironically, it was Wang’s research to benefit diabetes management and improve human health that led to his breakthrough in explosives detection. Wang has over 20 years experience in designing tiny sensors for commercial products to aid diabetics. This detection technology relies on an enzymatic test where blood glucose is converted to a hydrogen peroxide byproduct and measured by an electrochemical sensor.
“We took our expertise with blood glucose detection and our vision was to make something like a hand-held glucose meter, but toward the screening and detection of peroxide explosives” said Wang.
The highly sensitive assay Wang has developed can rapidly detect the two most common peroxide-based explosives, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), in trace amounts down to the part per billion level.
The approach, which is safe, irradiates these explosives with ultraviolet light, converting the TATP and HMTD into hydrogen peroxide. While a UV lamp system provides results in five minutes, the higher intensity laser irradiation greatly reduces the time down to 15 seconds.
The key to the technical innovation was employing what Wang describes as an ‘artificial peroxidase’ system, namely, a novel electrocatalyst that accelerates the electrochemical reaction of the liberated hydrogen peroxide.
“We can get very fast detection and now the goal is to integrate this into a high-performance, portable self-contained, easy-to-use device,” said Wang.
Though the final product may be down the road, Wang is actively working with the commercialization arm of ASU, Arizona Technology Enterprises (AzTE) to engage government and commercial partners to further develop the technology.