Tag: Georgia Institute of Technology

These Georgia universities are among the 50 best in the country

A new ranking of the country’s best colleges and universities has gone through 1,700 higher education institutions and determined which ones are top of the class.

Georgia ended up with three universities ranked in the top 50 nationwide.

According to U.S. News and World Report, Emory University is the best in the state, coming in at No. 24 on the national ranking.

The report says that with a total undergraduate enrollment of just over 7,400 and a 9:1 student-faculty ratio, Emory University ranks among most of the other universities nationwide.

It also mentions that the university has just a 10% acceptance rate, which is the 10th lowest in the country.

Earlier this month, officials announced that starting with the fall 2026 semester, all students whose parents make less than $200,000 will not have to pay tuition.

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Next up on the list, the Georgia Institute of Technology in Atlanta ranked No. 32 overall.

But if you remove private universities, Georgia Tech ranks in the top 10 for best public universities at No. 9.

It was also ranked the third most innovative school.

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But don’t worry, Bulldogs. The University of Georgia in Athens cracked the top 50 by coming in at No. 46.

Just like Georgia Tech, when looking only at public universities, UGA rises higher in the ranks, coming in at No. 19.

The report references UGA’s 767-acre campus and undergraduate population of more than 32,000 students, saying that despite having so many students, the student-faculty ratio is still 17:1.

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If you’re not looking to stay in the Peach State, U.S. News and World Report says the country’s best universities are Princeton University, Massachusetts Institute of Technology and Harvard University.

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September 23, 2025
Researchers Create Smaller, Cheaper Flow Batteries for Clean Energy

Newswise — Clean energy is the leading solution for climate change. But solar and wind power are inconsistent at producing enough energy for a reliable power grid. Alternatively, lithium-ion batteries can store energy but are a limited resource.

“The advantage of a coal power plant is it’s very steady,” said Nian Liu, an assistant professor at the Georgia Institute of Technology. “If the power source fluctuates like it does with clean energy, it makes it more difficult to manage, so how can we use an energy storage device or system to smooth out these fluctuations?”

Flow batteries offer a solution. Electrolytes flow through electrochemical cells from storage tanks in this rechargeable battery. The existing flow battery technologies cost more than $200/kilowatt hour and are too expensive for practical application, but Liu’s lab in the School of Chemical and Biomolecular Engineering (ChBE) developed a more compact flow battery cell configuration that reduces the size of the cell by 75%, and correspondingly reduces the size and cost of the entire flow battery. The work could revolutionize how everything from major commercial buildings to residential homes are powered.

The all-Georgia Tech research team published their findings in the paper, “A Sub-Millimeter Bundled Microtubular Flow Battery Cell With Ultra-high Volumetric Power Density,” in Proceedings of the National Academy of Sciences.

Finding the Flow

Flow batteries get their name from the flow cell where electron exchange happens. Their conventional design, the planar cell, requires bulky flow distributors and gaskets, increasing size and cost but decreasing overall performance. The cell itself is also expensive. To reduce footprint and cost, the researchers focused on improving the flow cell’s volumetric power density (W/L-of-cell).

They turned to a configuration commonly used in chemical separation — sub-millimeter, bundled microtubular (SBMT) membrane — made of a fiber-shaped filter membrane known as a hollow fiber. This innovation has a space-saving design that can mitigate pressure across the membranes that ions pass through without needing additional support infrastructure.

“We were interested in the effect of the battery separator geometry on the performance of flow batteries,” said Ryan Lively, a professor in ChBE. “We were aware of the advantages that hollow fibers imparted on separation membranes and set out to realize those same advantages in the battery field.”

Applying this concept, the researchers developed an SMBT that reduces membrane-to-membrane distance by almost 100 times. The microtubular membrane in the design works as an electrolyte distributor at the same time without the need for large supporting materials. The bundled microtubes create a shorter distance between electrodes and membranes, increasing the volumetric power density. This bundling design is the key discovery for maximizing flow batteries’ potential.

Powering the Battery

To validate their new battery configuration, the researchers used four different chemistries: vanadium, zinc-bromide, quinone-bromide, and zinc-iodide. Although all chemistries are functional, two were most promising. Vanadium was the most mature chemistry, but also less accessible, and the reduced form of it is unstable in air. They found zinc iodide was the most energy-dense option, making it the most effective for residential units. Zinc-iodide offered many advantages even compared to lithium: It has less of a supply chain issue and also can be turned into zinc oxide and dissolve in acid, making it much easier to recycle.

This electrochemical solution for this unique shape of the flow battery proved more powerful than conventional planar cells.

“The superior performance of the SMBT was also demonstrated by finite element analysis,” said Xing Xie, an assistant professor in the School of Civil and Environmental Engineering. “This simulation method will also be applied in our future study for cell performance optimization and scaling up.”

With zinc-iodide chemistry, the battery could run for more than 220 hours, or to > 2,500 cycles at off-peak conditions. It could also potentially reduce the cost from $800 to less than $200 per kilowatt hour by using recycled electrolyte.

Building the Future of Energy

The researchers are already working on commercialization, focusing on developing batteries with different chemistries like vanadium and scaling up their size. Scaling will require coming up with an automated process to manufacture a hollow fiber module, which now is done manually, fiber by fiber. They eventually hope to deploy the battery in Georgia Tech’s 1.4-megawatt microgrid in Tech Square, a project that tests microgrid integration into the power grid and offers living laboratory for professors and students.

The SBMT cells could also be applied to different energy storage systems like electrolysis and fuel cells. The technology could even be strengthened with advanced materials and different chemistry in various applications.

“This innovation is very application driven,” Liu said. “We have the need to reach carbon neutrality by increasing the percentage of renewable energy in our energy generation, and right now, it’s less than 15% in the U.S. Our research could change this.”

Yutong Wu, Fengyi Zhang, Ting Wang, Po-Wei Huang, Alexandros Filippas, Haochen Yang, Yanghang Huang, Chao Wang, Huitian Liu, Xing Xie, Ryan P. Lively, Nian Liu, “A Submillimeter Bundled Microtubular Flow Battery Cell with Ultrahigh Volumetric Power Density.” PNAS (2023).

DOI: https://doi.org/10.1073/pnas.2213528120

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The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 46,000 students, representing 50 states and more than 150 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Georgia Institute of Technology

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January 13, 2023
Cat Locomotion Could Unlock Better Human Spinal Cord Injury Treatment

Newswise — Cats always land on their feet, but what makes them so agile? Their unique sense of balance has more in common with humans than it may appear. Researchers at the Georgia Institute of Technology are studying cat locomotion to better understand how the spinal cord works to help humans with partial spinal cord damage walk and maintain balance.

Using a mix of experimental studies and computational models, the researchers show that somatosensory feedback, or neural signals from specialized sensors throughout a cat’s body, help inform the spinal cord about the ongoing movement and coordinate the four limbs to keep cats from falling when they encounter obstacles. Research suggests that with those motion-related sensory signals the animal can walk even if the connection between the spinal cord and the brain is partially fractured.

Understanding the mechanisms of this type of balance control is particularly relevant to older people who often have balance issues and can injure themselves in falls. Eventually, the researchers hope this could bring new understanding to somatosensory feedback’s role in balance control. It could also lead to progress in spinal cord injury treatment because the research suggests activation of somatosensory neurons can improve spinal neural networks’ function below the site of spinal cord damage.

“We have been interested in the mechanisms that make it possible to reactivate injured networks in the spinal cord,” said School of Biological Sciences Professor Boris Prilutsky. “We know from previous studies that somatosensory feedback from moving legs helps activate spinal networks that control locomotion, enabling stable movement.”

The researchers presented their findings in “Sensory Perturbations From Hindlimb Cutaneous Afferents Generate Coordinated Functional Responses in All Four Limbs During Locomotion in Intact Cats” in the journal eNeuro.

Coordinated Cats

Although genetically modified mouse models have recently become dominant in neural control of locomotion research, the cat model offers an important advantage. When they move, mice remain crouched, meaning they are less likely to have balance problems even if somatosensory feedback fails. Humans and cats, on the other hand, cannot maintain balance or even move if they lose sensory information about limb motion. This suggests that larger species, like cats and humans, might have a different organization of spinal neural network controlling locomotion compared to rodents.

Georgia Tech partnered with researchers at the University of Sherbrooke in Canada and Drexel University in Philadelphia to better understand how signals from sensory neurons coordinate movements of the four legs. The Sherbrooke lab trained cats to walk on a treadmill at a pace consistent with human gait and then used electrodes to stimulate their sensory nerve.

The researchers focused on the sensory nerve that transmits touch sensation from the top of the foot to the spinal cord. By electrically stimulating this nerve, researchers mimicked hitting an obstacle and saw how the cats stumbled and corrected their movement in response. Stimulations were applied in four periods of the walking cycle: mid-stance, stance-to-swing transition, mid-swing, and swing-to-stance transition. From this, they learned that mid-swing and the stance-to-swing transition were the most significant periods because the stimulation increased activity in muscles that flex the knee and hip joints, joint flexion and toe height, step length, and step duration of the stimulated limb.

“In order to maintain balance, the animal must coordinate movement of the other three limbs, otherwise it would fall,” Prilutsky said. “We found that stimulation of this nerve during the swing phase increases the duration of the stance phase of the other limbs and improves stability.”

In effect, when the cat stumbles during the swing phase, the sensation triggers spinal reflexes that ensure the three other limbs stay on the ground and keep the cat upright and balanced, while the swing limb steps over the obstacle.

Computational Cats

With these Canadian lab experiments, the researchers at Georgia Tech and Drexel University are using observations to develop a computational model of the cat’s musculoskeletal and spinal neural control systems. The data gathered are used to compute somatosensory signals related to length, velocity, and produced force of muscles, as well as pressure on the skin in all limbs. This information forms motion sensations in the animal’s spinal cord and contributes to interlimb coordination by the spinal neuronal networks.

“To help treat any disease, we need to understand how the intact system works,” Prilutsky said. “That was one reason why this study was performed, so we could understand how the spinal networks coordinate limb movements and develop a realistic computational model of spinal control of locomotion. This will help us know better how the spinal cord controls locomotion.”

CITATION: Merlet AN, Jéhannin P, Mari S, Lecomte CG, Audet J, Harnie J, Rybak IA, Prilutsky BI, Frigon A (2022) Sensory Perturbations from Hindlimb Cutaneous Afferents Generate Coordinated Functional Responses in All Four Limbs during Locomotion in Intact Cats. eNeuro 9: 0178-22.

DOI: 10.1523/ENEURO.0178-22.2022

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The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 46,000 students, representing 50 states and more than 150 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Georgia Institute of Technology

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January 9, 2023
Cheerful Chatbots Don’t Necessarily Improve Customer Service

Newswise — Imagine messaging an artificial intelligence (AI) chatbot about a missing package and getting the response that it would be “delighted” to help. Once the bot creates the new order, they say they are “happy” to resolve the issue. After, you receive a survey about your interaction, but would you be likely to rate it as positive or negative?

This scenario isn’t that far from reality, as AI chatbots are already taking over online commerce. By 2025, 95% of companies will have an AI chatbot, according to Finance Digest. AI might not be sentient yet, but it can be programmed to express emotions.

Humans displaying positive emotions in customer service interactions have long been known to improve customer experience, but researchers at the Georgia Institute of Technology’s Scheller College of Business wanted to see if this also applied to AI. They conducted experimental studies to determine if positive emotional displays improved customer service and found that emotive AI is only appreciated if the customer expects it, and it may not be the best avenue for companies to invest in.

“It is commonly believed and repeatedly shown that human employees can express positive emotion to improve customers’ service evaluations,” said Han Zhang, the Steven A. Denning Professor in Technology & Management. “Our findings suggest that the likelihood of AI’s expression of positive emotion to benefit or hurt service evaluations depends on the type of relationship that customers expect from the service agent.”

The researchers presented their findings in the paper, “Bots With Feelings: Should AI Agents Express Positive Emotion in Customer Service?,” in Information Systems Research in December.

Studying AI Emotion

The researchers conducted three studies to expand the understanding of emotional AI in customer service transactions. Although they changed the participants and scenario in each study, AI chatbots imbued with emotion used positive emotional adjectives, such as excited, delighted, happy, or glad. They also deployed more exclamation points.

The first study focused on whether customers responded more favorably to positive emotion if they knew the customer agent was a bot or person. Participants were told they were seeking help for a missing item in a retail order. The 155 participants were then randomly assigned to four different scenarios: human agents with neutral emotion, human agents with positive emotion, bots with neutral emotion, and bots with positive emotion. Then they asked participants about service quality and overall satisfaction. The results indicated that positive emotion was more beneficial when human agents exhibited it, but it had no effect when bots exhibited it.

The second study examined if customers’ personal expectations determined their reaction to the bot. In this scenario, the 88 participants imagined returning a textbook and were randomly assigned to either emotion-positive or emotion-neutral bots. After chatting with the bot, they were asked to rate if they were communal (social) oriented or exchange (transaction) oriented on a scale. If the participant was communal-focused, they were more likely to appreciate the positive emotional bot, but if they expected the exchange as merely transactional, the emotionally positive bot made their experience worse.

“Our work enables businesses to understand the expectations of customers exposed to AI-provided services before they haphazardly equip AIs with emotion-expressing capabilities,” Zhang said.

The final study explored why a bot’s positive emotion influences customer emotions, following 177 undergraduate students randomly assigned to emotive or non-emotive bots. The results explained why positive bots have less of an effect than anticipated. Because customers do not expect machines to have emotions, they can react negatively to emotion in a bot.

The results across the studies show that using positive emotion in chatbots is challenging because businesses don’t know a customer’s biases and expectations going into the interaction. A happy chatbot could lead to an unhappy customer.

“Our findings suggest that the positive effect of expressing positive emotion on service evaluations may not materialize when the source of the emotion is not a human,” Zhang said. “Practitioners should be cautious about the promises of equipping AI agents with emotion-expressing capabilities.”

CITATION: Han, Elizabeth and Yin, Dezhi and Zhang, Han (2022) Bots with Feelings: Should AI Agents Express Positive Emotion in Customer Service?. Information Systems Research.

Published online in Articles in Advance 02 Dec 2022

DOI: https://doi.org/10.1287/isre.2022.1179

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The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 46,000 students, representing 50 states and more than 150 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Georgia Institute of Technology

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December 21, 2022
Using Machine Learning to Better Understand How Water Behaves

Newswise — Water has puzzled scientists for decades. For the last 30 years or so, they have theorized that when cooled down to a very low temperature like -100C, water might be able to separate into two liquid phases of different densities. Like oil and water, these phases don’t mix and may help explain some of water’s other strange behavior, like how it becomes less dense as it cools.

It’s almost impossible to study this phenomenon in a lab, though, because water crystallizes into ice so quickly at such low temperatures. Now, new research from the Georgia Institute of Technology uses machine learning models to better understand water’s phase changes, opening more avenues for a better theoretical understanding of various substances. With this technique, the researchers found strong computational evidence in support of water’s liquid-liquid transition that can be applied to real-world systems that use water to operate.

“We are doing this with very detailed quantum chemistry calculations that are trying to be as close as possible to the real physics and physical chemistry of water,” said Thomas Gartner, an assistant professor in the School of Chemical and Biomolecular Engineering at Georgia Tech. “This is the first time anyone has been able to study this transition with this level of accuracy.”

The research was presented in the paper, “Liquid-Liquid Transition in Water From First Principles,” in the journal Physical Review Letters, with co-authors from Princeton University.

Simulating Water

To better understand how water interacts, the researchers ran molecular simulations on supercomputers, which Gartner compared to a virtual microscope.

“If you had an infinitely powerful microscope, you could zoom in all the way down to the level of the individual molecules and watch them move and interact in real time,” he said. “This is what we’re doing by creating almost a computational movie.”

The researchers analyzed how the molecules move and characterized the liquid structure at different water temperatures and pressures, mimicking the phase separation between the high and low-density liquids. They collected extensive data — running some simulations for up to a year — and continued to fine-tune their algorithms for more accurate results.

Even a decade ago, running such long and detailed simulations wouldn’t have been possible, but machine learning today offered a shortcut. The researchers used a machine learning algorithm that calculated the energy of how water molecules interact with each other. This model performed the calculation significantly faster than traditional techniques, allowing the simulations to progress much more efficiently.

Machine learning isn’t perfect, so these long simulations also improved the accuracy of the predictions. The researchers were careful to test their predictions with different types of simulation algorithms. If multiple simulations gave similar results, then it validated their accuracy.

“One of the challenges with this work is that there’s not a lot of data that we can compare to because it’s a problem that’s almost impossible to study experimentally,” Gartner said. “We’re really pushing the boundaries here, so that’s another reason why it’s so important that we try to do this using multiple different computational techniques.”

Beyond Water

Some of the conditions the researchers tested were extremes that probably don’t exist on Earth directly, but potentially could be present in various water environments of the solar system, from the oceans of Europa to water in the center of comets. Yet these findings could also help researchers better explain and predict water’s strange and complex physical chemistry, informing water’s use in industrial processes, developing better climate models, and more.

The work is even more generalizable, according to Gartner. Water is a well-studied research area, but this methodology could be expanded to other difficult-to-simulate materials like polymers, or complex phenomena like chemical reactions.

“Water is so central to life and industry, so this particular question of whether water can undergo this phase transition has been a longstanding problem, and if we can move toward an answer, that’s important,” he said. “But now we have this really powerful new computational technique, but we don’t yet know what the boundaries are and there’s a lot of room to move the field forward.”

CITATION: T.E. Gartner, III, P.M. Piaggi, R. Car, A.Z. Panagiotopoulos, P.G. Debenedetti, “Liquid-liquid transition in water from first principles,”* Phys. Rev. Lett., 2022.

DOI:10.1103/PhysRevLett.129.255702

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The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 46,000 students, representing 50 states and more than 150 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Georgia Institute of Technology

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December 16, 2022
Inexpensive Airborne Testbeds Could Study Hypersonic Technologies

Newswise — Miniature satellites known as CubeSats are taking on larger roles in space missions that might previously have been carried out by more expensive conventional spacecraft. Now, researchers at the Georgia Institute of Technology are envisioning a still larger mission for CubeSats as airborne testbeds for technologies that are being developed for future generations of hypersonic vehicles.

Development of hypersonic vehicles able to travel through the Earth’s atmosphere at Mach 5 or faster – five times the speed of sound – is attracting substantial new government and industry funding. But test facilities needed to evaluate thermodynamic, aerodynamic, acoustic, and other issues critical to operating in that harsh environment are limited, in high demand, and costly to use.

Georgia Tech researchers want to eliminate that roadblock by building hardened CubeSats that could use re-entry from space to generate the conditions needed to evaluate hypersonic technologies. The small satellites, with their key systems protected from the heat of re-entry, would be launched into the upper atmosphere from the International Space Station or a “rideshare” rocket to provide several minutes of testing at velocities of up to Mach 25.

“We are looking at the feasibility of building what would be an inexpensive flying wind tunnel,” said Krish Ahuja, Regents Professor of Aerospace Engineering and division chief for aerospace and acoustics in the Aerospace, Transportation, and Advanced Systems Laboratory of the Georgia Tech Research Institute (GTRI) and the project’s principal investigator. “We could gather pretty much any data that would be needed for hypersonic research and provide a new way to conduct studies that now can be quite difficult to do.”

Initial Study Suggests Developing 6U Vehicle

Based on a six-month feasibility study that included collaborators from Georgia Tech’s School of Aerospace Engineering and two private companies, Ahuja believes it would be worthwhile to pursue design of a 6U test vehicle to evaluate the concept. (A 6U CubeSat is about the size of the system unit of a desktop computer). If that proves promising, larger vehicles could be constructed with more capable instrumentation, guidance, and even propulsion.

The goal of the project’s first year is to understand what would be required to develop and launch the flying testbeds – and recover them after flight. Design and development of the new test vehicles must overcome significant challenges related to controlling the flight duration, speed, altitude, and orientation of the vehicle during data collection. Systems to communicate with the ground and track the vehicle’s trajectory must also be developed. Also, part of the first-year goal is creation of a roadmap showing the development and test process.

“Ongoing work will include a ‘system-of-systems’ analysis of the concept to model its performance and interaction with other support systems to assess its capability to conduct scientific research,” Ahuja said. “Our initial calculations indicate that a 6U CubeSat could be hardened with a thermal protection system for hypersonic conditions to help conduct limited feasibility experiments. This will be a building block for future systems that would be larger and able to conduct the testing we envision.”

Initial testing is likely to involve free fall of the test vehicle, but subsequent tests would include control surfaces that would provide steering to prevent tumbling and other undesired effects. Multiple CubeSats could also be operated together.

Possible New Capabilities for Small Satellites

CubeSats, so-called because they are designed in standard cube sizes, aren’t normally designed to be recovered after a mission; when their work is done, they simply burn up in the atmosphere. Because Ahuja wants to study effects on materials and capture data from on-board instruments, the flying wind tunnel satellites will need to be recovered using parachutes that would drop them into a recovery zone, perhaps in the desert Southwest.

“Getting them down at the right location will require good guidance and control, good telemetry, and a propulsion system,” he said. “The challenge will be to make these very small and inexpensive. To get the information we need, we will have to bring the testbed safely to the ground.”

The high temperatures generated by re-entry into the Earth’s atmosphere could be useful for more than simulating hypersonic conditions. Ahuja believes the heat could be used to operate a proprietary device that could provide steering for the CubeSats, which normally don’t have propulsion systems.

Much of current research on hypersonic flight depends on data from computational fluid dynamics simulations, which need validation from testing. Beyond the information gained from the testbed, Ahuja believes the small spacecraft could make big contributions by providing a real-world anchor for the analysis tools that researchers are using for a variety of hypersonic vehicles.

A New Approach to Hypersonic Testing is Needed

Hypersonic testing is typically done in short-duration wind tunnels or high-temperature testbeds, meaning high-speed and high-temperature conditions are difficult to achieve simultaneously and at test durations relevant to hypersonic vehicles. In addition, there are few existing facilities where such testing can be done, and they are in high demand. The new testbed is expected to provide about three minutes of testing per flight.

Currently, there is a critical need to understand how much and what kind of thermal protection system is needed to protect hypersonic vehicles at high velocities where friction can produce temperatures of more than 4,000 degrees F. Additionally, there are questions about acoustic effects and how uneven heating will spread across a vehicle and potentially damage its structure.

“The airflow across a hypersonic vehicle can be both turbulent and laminar, different on different parts of the vehicle,” said Ahuja. “These wide variations of the flow properties can produce large variation in temperatures over the vehicle surface, which is highly undesirable with respect to vehicle’s structural integrity. As such, we need to understand what is happening to the material as a result of temperature changes over time. This thermal loading cannot be studied in conventional wind tunnels, which normally offer fractions of seconds of run time at hypersonic conditions, because it takes a while for those conditions to become steady.”

Acoustic loading can also dramatically affect the structural integrity of a hypersonic vehicle, and that likewise requires time to evaluate. “Acoustic loading of the kind that could generate a crack in a structure that develops over time,” he said. “We could create and study these conditions with our flying testbed.”

Funding from GTRI’s Independent Research and Development (IRAD) program has supported the initiative so far, and by gathering enough data from the initial studies, Ahuja hopes to attract collaborators to help implement the new test approach.

“There is so much enthusiasm for this that I believe our chances of success are high,” he said. “By launching from another space system, we won’t have to worry about the initial launch propulsion. This could address a lot of challenges in conducting hypersonic research.”

Georgia Institute of Technology

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December 4, 2022
Exploring Europa Possible with Silicon-Germanium Transistor Technology

Newswise — Europa is more than just one of Jupiter’s many moons – it’s also one of most promising places in the solar system to look for extraterrestrial life. Under 10 kilometers of ice is a liquid water ocean that could sustain life. But with surface temperatures at -180 Celsius and with extreme levels of radiation, it’s also one of the most inhospitable places in the solar system. Exploring Europa could be possible in the coming years thanks to new applications for silicon-germanium transistor technology research at Georgia Tech.

Regents’ Professor John D. Cressler in the School of Electrical and Computer Engineering (ECE) and his students have been working with silicon-germanium heterojunction bipolar transistors (SiGe HBTs) for decades and have found them to have unique advantages in extreme environments like Europa.

“Due to the way that they’re made, these devices actually survive those extreme conditions without any changes made to the underlying technology itself,” said Cressler, who is the project investigator. “You can build it for what you want it to do on Earth, and you then can use it in space.”

The researchers are in year one of a three-year grant in the NASA Concepts for Ocean Worlds Life Detection Technology (COLDTech) program to design the electronics infrastructure for upcoming Europa surface missions. NASA plans to launch the Europa Clipper in 2024, an orbiting spacecraft that will map the oceans of Europa, and then eventually send a landing vehicle, Europa Lander, to drill through the ice and explore its ocean. But it all starts with electronics that can function in Europa’s extreme environment.

Cressler and his students, together with researchers from NASA Jet Propulsion Lab (JPL) and the University of Tennessee (UT), demonstrated the capabilities of SiGe HBTs for this hostile environment in a paper presented at the IEEE Nuclear and Space Radiation Effects Conference in July.

Europa’s Challenge

Like Earth, Jupiter also has a liquid metal core that generates a magnetic field, producing radiation belts of high-energy protons and electrons from the impinging solar wind. Unfortunately, as a moon of Jupiter, Europa sits squarely in those radiation belts. In effect, any technology designed for Europa’s surface would not only need to be able to survive the cold temperatures but also the worst radiation encountered in the solar system.

Fortunately, SiGe HBTs are ideal for this hostile environment. The SiGe HBT introduces a nanoscale Si-Ge alloy inside a typical bipolar transistor to nano-engineer its properties, effectively producing a much faster transistor while maintaining the economy-of-scale and low cost of traditional silicon transistors. SiGe HBTs have the unique ability to maintain performance under extreme radiation exposure, and their properties naturally improve at colder temperatures. Such a unique combination makes them ideal candidates for Europa exploration.

“It’s not just doing the basic science and proving that SiGe works,” Cressler said. “It’s actually developing electronics for NASA to use on Europa. We know SiGe can survive high levels of radiation. And we know it’s remains functional at cold temperatures. What we did not know is if it could do both at the same time, which is needed for Europa surface missions.”

Testing the Transistors

To answer this question, the GT researchers used JPL’s Dynamitron, a machine that shoots high-flux electrons at very low temperatures to test SiGe in Europa-type environments. They exposed SiGe HBTs to one million Volt electrons to a radiation dose of five million rads of radiation (200-400 rads is lethal to humans), at 300, 200, and 115 Kelvins (-160 Celsius).

“What had never been done was to use electronics like we did in that experiment,” Cressler said. “So, we worked literally for the first year to get the results that are in that paper, which is in essence definitive proof that what we claimed is, in fact, true—that SiGe does survive Europa surface conditions.”

In the next two years, the GT and UT researchers will develop actual circuits from SiGe that could be used on Europa, such as radios and microcontrollers. Yet more importantly, these devices could then be seamlessly used in almost any space environment, including on the moon and Mars.

“If Europa is the worst-case environment in the solar system, and you can build these to work on Europa, then they will work anywhere,” Cressler said. “This research ties together past research that we have done in my team here at Georgia Tech for a long time and shows really interesting and novel applications of these technologies. We pride ourselves on using our research to break new innovative ground and thereby enable novel applications.”

Citation: J.W. Teng, G.N. Tzintzarov, D. Nergui, J.P. Heimerl, Y. Mensah, J.P. Moody, D.O. Thorbourn, L. Del Castillo, L. Scheick, M.M. Mojarradi, B.J. Blalock, and J.D. Cressler, “Cryogenic Total-Ionizing-Dose Response of 4th-Generation SiGe HBTs using 1-MeV Electrons for Europa-Surface Applications,” IEEE Nuclear and Space Radiation Effects Conference, July 2022.

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The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition.

The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 46,000 students, representing 50 states and more than 150 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning.

As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Georgia Institute of Technology

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September 30, 2022