Showing posts with label Hugh Churchill. Show all posts
Showing posts with label Hugh Churchill. Show all posts

Tuesday, April 21, 2020

NSF Funds Multidisciplinary U of A Team to Improve Imaging Technology


From left: Magda El-Shenawee, principal investigator and professor of electrical engineering; Hugh Churchill, assistant professor of physics; and Robert Coridan, assistant professor of chemistry.
https://news.uark.edu/articles/52782/nsf-funds-multidisciplinary-u-of-a-team-to-improve-imaging-technology

University of Arkansas researchers received funding from the National Science Foundation to advance imaging technology that could help improve breast cancer treatment, protect airline travelers and advance the nation's 5G network.
Three professors were awarded $456,070 from the NSF to support their research into high-frequency antennas, which are a critical part of imaging technology. The team is composed of Magda El-Shenawee, principal investigator and professor of electrical engineering, Hugh Churchill, assistant professor of physics, and Robert Coridan, assistant professor of chemistry.
Researchers are working to create more effective terahertz photoconductive antennas by using a new material — black phosphorus. The research includes three main components, modeling, fabrication, and measurements.
Terahertz radiation falls between infrared and microwave radiation on the electromagnetic spectrum. It is useful for a variety of applications because it can penetrate non-conductive materials like clothing, cardboard and wood, however, its penetration of body tissue is in micrometers.
El-Shenawee's research has been focused for years on terahertz technology to improve imaging for use in identifying breast cancer tumor margins to help doctors make better decisions when assigning treatments. She previously developed terahertz antennas based on plasmonic nano-disks using low temperature Gallium Arsenide (GaAs). The idea to use black phosphorous in this new project came from Churchill, a physicist whose research interests include 2-D semiconductors, like black phosphorous. The collaboration began through a project made possible by the Chancellor's Fund for Innovation and Collaboration.
That collaboration allowed the pair to examine whether black phosphorous would work as a component of terahertz antennas, and computer simulations suggested it could be 10 times more effective than current technology. They'll also work with dielectric nanoparticle coatings, which Coridan uses in his solar cell research, to increase the efficiency of the new antenna.  
"We want to maximize the fraction of the incident light that is absorbed in the black phosphorous layer," Coridan said. "Adding a layer of nanoparticles will scatter light in directions that will make the black phosphorous seem to be thicker than it is. This passive structure increases the light absorption in the black phosphorous layer, while reducing reflection or absorption of other parts of the device."
Black phosphorous could also increase the speed of communication between devices on the 5G network, which has a wide variety of applications. 
"If your car has 5G technology, it has an antenna to communicate with other vehicles to detect its location. This detection allows the vehicle to stop automatically when it needs to, so improving the signal speed between these devices can help vehicles sense objects faster, reducing the chances of an accident," El-Shenawee said.
El-Shenawee said the project is a unique collaboration.
"This is my first time working with three different disciplines on a promising idea like this one," El-Shenawee said. "The three of us think differently, but it is quite interesting."
Churchill said the team is excited and grateful for the support they have received.
"I would like to express our team's gratitude for the phenomenal institutional boost our team received to catalyze this interdisciplinary effort, which included Chancellor's Fund support to obtain preliminary data and Arkansas Biosciences Institute support to obtain crucial equipment to test our novel devices," he said.

OUTREACH TARGETING UNDERREPRESENTED STUDENTS

The NSF funding will also support outreach initiatives geared toward underrepresented K-12 students and their teachers in Arkansas.
"When we presented the concepts of antennas and wave traveling to students in K-12 summer camps, they were very excited," El-Shenawee said. 
The camps are coordinated by Amy Warren, assistant director of outreach and summer programs in the College of Engineering.
El-Shenawee said the team will work with Warren on creating unique opportunities and activities for underrepresented students in Arkansas.
"Even the youngest students are familiar with technologies that utilize antennas, but most do not gain any understanding of the concepts underlying this technology until high school," Warren said. "The outreach initiatives will give K-8 teachers and students the tools needed to teach these complex concepts earlier."
El-Shenawee, Churchill and Coridan said they hope this will encourage students to consider majoring in science and engineering-based fields.
The team hopes to have the project completed by 2023.

Saturday, August 25, 2018

Tiny Antennas Show Promise in Defense Sector



https://news.uark.edu/articles/42541/tiny-antennas-show-promise-in-defense-sector

Electrical engineering research into extremely small antennas has made progress that could have a major impact on secure information exchange, giving the U.S. access to a band of frequency no other country can reach.
Electrical engineering professor Magda El-Shenawee's Terahertz Imaging and Spectroscopy Lab is known for its revolutionary research on the detection of breast cancer tumors using terahertz imaging technology. Now, El-Shenawee has published a paper suggesting terahertz antennas could have their signals strengthened for use in transmitting information.
Her paper, titled "Plasmonic Nanodisk Thin-film Terahertz Photoconductive Antenna," was presented at the international conference of Antennas and Propagation in Boston last month. The research was conducted in collaboration with TeraView Ltd., a major manufacturer of terahertz systems in the United Kingdom.
Terahertz antennas are tiny, only a fraction of a millimeter in size. By comparison, the microwave antennas used in cell phones are more than 10 times that size. The newly created terahertz antennas have sent researchers around the world racing to improve its efficiency.
Current antennas on the market provide very low power, a fraction of a milliwatt, which is adequate for some applications, such as breast cancer imaging. However, current power limitations make the antenna inferior for use in potential applications such as radar systems for defense and high-speed wireless communications.
The challenge, El-Shenawee said, is that the strength of a terahertz wave weakens when it travels because of its sensitivity to water, including humidity in the air. For the wave to travel longer distances, the transmitting terahertz antenna needs to radiate electromagnetic waves of higher power at the source.
El-Shenawee's idea for improving the terahertz antenna's efficiency involves advancing the antenna material and design. She is collaborating with Hugh Churchill, a material scientist and assistant professor of physics in the J. William Fulbright College of Arts and Sciences, and Miaoqing Huang, an associate professor of computer science in the College of Engineering.
The group's plan is to provide superior terahertz emission built on plasmonic thin-film device architecture. Early results have show a three-fold increase in power output.
Shenawee's current terahertz antenna was built using nanodisk arrays on top of a thin film of a semiconductor. In this case, low temperature grown Gallium Arsenide, a typical material for this type of antennas, was used. The antenna is excited by femtosecond laser, with antenna electrodes located below the semiconductor to increase the light trapped in the semiconductor and the photocurrent, and hence the radiated terahertz power.
So far, the achieved power is 3 microwatts, compared to conventional antennas that provide 1 microwatt.
High-powered terahertz antennas like the one proposed by El-Shenawee's research have applications in high-speed electronics wireless communication. El-Shenwaee said applications in defense communication, especially concerning reliable transmission and secure information exchange, can be significant.
"If we can advance terahertz antennas by advancing their output power, the U.S. will be using a band of frequency that no other country has the technology for yet," she said.

CONTACTS
Magda El-Shenawee, professor 
Department of Electrical Engineering 
479-575-6582, magda@uark.edu
Nick DeMoss, director of communications 
College of Engineering 
479-575-5697, ndemoss@uark.edu