Tag Archives: UT Austin

Bioinspired ‘smart’ materials a step towards soft robotics and electronics

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An October 13, 2022 news item on Nanowerk describes some new work from the University of Texas at Austin,

Inspired by living things from trees to shellfish, researchers at The University of Texas at Austin set out to create a plastic much like many life forms that are hard and rigid in some places and soft and stretchy in others.

Their success — a first, using only light and a catalyst to change properties such as hardness and elasticity in molecules of the same type — has brought about a new material that is 10 times as tough as natural rubber and could lead to more flexible electronics and robotics.

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An October 13, 2022 University of Texas at Austin news release (also on EurekAlert), which originated the news item, delves further into the work,

“This is the first material of its type,” said Zachariah Page, assistant professor of chemistry and corresponding author on the paper. “The ability to control crystallization, and therefore the physical properties of the material, with the application of light is potentially transformative for wearable electronics or actuators in soft robotics.”

Scientists have long sought to mimic the properties of living structures, like skin and muscle, with synthetic materials. In living organisms, structures often combine attributes such as strength and flexibility with ease. When using a mix of different synthetic materials to mimic these attributes, materials often fail, coming apart and ripping at the junctures between different materials.

Oftentimes, when bringing materials together, particularly if they have very different mechanical properties, they want to come apart,” Page said. Page and his team were able to control and change the structure of a plastic-like material, using light to alter how firm or stretchy the material would be.

Chemists started with a monomer, a small molecule that binds with others like it to form the building blocks for larger structures called polymers that were similar to the polymer found in the most commonly used plastic. After testing a dozen catalysts, they found one that, when added to their monomer and shown visible light, resulted in a semicrystalline polymer similar to those found in existing synthetic rubber. A harder and more rigid material was formed in the areas the light touched, while the unlit areas retained their soft, stretchy properties.

Because the substance is made of one material with different properties, it was stronger and could be stretched farther than most mixed materials.

The reaction takes place at room temperature, the monomer and catalyst are commercially available, and researchers used inexpensive blue LEDs as the light source in the experiment. The reaction also takes less than an hour and minimizes use of any hazardous waste, which makes the process rapid, inexpensive, energy efficient and environmentally benign.

The researchers will next seek to develop more objects with the material to continue to test its usability.

“We are looking forward to exploring methods of applying this chemistry towards making 3D objects containing both hard and soft components,” said first author Adrian Rylski, a doctoral student at UT Austin.

The team envisions the material could be used as a flexible foundation to anchor electronic components in medical devices or wearable tech. In robotics, strong and flexible materials are desirable to improve movement and durability.

…

Here’s a link to and a citation for the paper,

Polymeric multimaterials by photochemical patterning of crystallinity by Adrian K. Rylski, Henry L. Cater, Keldy S. Mason, Marshall J. Allen, Anthony J. Arrowood, Benny D. Freeman, Gabriel E. Sanoja, and Zachariah A. Page. Science 13 Oct 2022 Vol 378, Issue 6616 pp. 211-215 DOI: 10.1126/science.add6975

This paper is behind a paywall.

Evolution of literature as seen by a classicist, a biologist and a computer scientist

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Studying intertextuality shows how books are related in various ways and are reorganized and recombined over time. Image courtesy of Elena Poiata.

I find the image more instructive when I read it from the bottom up. For those who prefer to prefer to read from the top down, there’s this April 5, 2017 University of Texas at Austin news release (also on EurekAlert),

A classicist, biologist and computer scientist all walk into a room — what comes next isn’t the punchline but a new method to analyze relationships among ancient Latin and Greek texts, developed in part by researchers from The University of Texas at Austin.

Their work, referred to as quantitative criticism, is highlighted in a study published in the Proceedings of the National Academy of Sciences. The paper identifies subtle literary patterns in order to map relationships between texts and more broadly to trace the cultural evolution of literature.

“As scholars of the humanities well know, literature is a system within which texts bear a multitude of relationships to one another. Understanding what is distinctive about one text entails knowing how it fits within that system,” said Pramit Chaudhuri, associate professor in the Department of Classics at UT Austin. “Our work seeks to harness the power of quantification and computation to describe those relationships at macro and micro levels not easily achieved by conventional reading alone.”

In the study, the researchers create literary profiles based on stylometric features, such as word usage, punctuation and sentence structure, and use techniques from machine learning to understand these complex datasets. Taking a computational approach enables the discovery of small but important characteristics that distinguish one work from another — a process that could require years using manual counting methods.

“One aspect of the technical novelty of our work lies in the unusual types of literary features studied,” Chaudhuri said. “Much computational text analysis focuses on words, but there are many other important hallmarks of style, such as sound, rhythm and syntax.”

Another component of their work builds on Matthew Jockers’ literary “macroanalysis,” which uses machine learning to identify stylistic signatures of particular genres within a large body of English literature. Implementing related approaches, Chaudhuri and his colleagues have begun to trace the evolution of Latin prose style, providing new, quantitative evidence for the sweeping impact of writers such as Caesar and Livy on the subsequent development of Roman prose literature.

“There is a growing appreciation that culture evolves and that language can be studied as a cultural artifact, but there has been less research focused specifically on the cultural evolution of literature,” said the study’s lead author Joseph Dexter, a Ph.D. candidate in systems biology at Harvard University. “Working in the area of classics offers two advantages: the literary tradition is a long and influential one well served by digital resources, and classical scholarship maintains a strong interest in close linguistic study of literature.”

Unusually for a publication in a science journal, the paper contains several examples of the types of more speculative literary reading enabled by the quantitative methods introduced. The authors discuss the poetic use of rhyming sounds for emphasis and of particular vocabulary to evoke mood, among other literary features.

“Computation has long been employed for attribution and dating of literary works, problems that are unambiguous in scope and invite binary or numerical answers,” Dexter said. “The recent explosion of interest in the digital humanities, however, has led to the key insight that similar computational methods can be repurposed to address questions of literary significance and style, which are often more ambiguous and open ended. For our group, this humanist work of criticism is just as important as quantitative methods and data.”

The paper is the work of the Quantitative Criticism Lab (www.qcrit.org), co-directed by Chaudhuri and Dexter in collaboration with researchers from several other institutions. It is funded in part by a 2016 National Endowment for the Humanities grant and the Andrew W. Mellon Foundation New Directions Fellowship, awarded in 2016 to Chaudhuri to further his education in statistics and biology. Chaudhuri was one of 12 scholars selected for the award, which provides humanities researchers the opportunity to train outside of their own area of special interest with a larger goal of bridging the humanities and social sciences.

Here’s another link to the paper along with a citation,

Quantitative criticism of literary relationships by Joseph P. Dexter, Theodore Katz, Nilesh Tripuraneni, Tathagata Dasgupta, Ajay Kannan, James A. Brofos, Jorge A. Bonilla Lopez, Lea A. Schroeder, Adriana Casarez, Maxim Rabinovich, Ayelet Haimson Lushkov, and Pramit Chaudhuri. PNAS Published online before print April 3, 2017, doi: 10.1073/pnas.1611910114

This paper appears to be open access.

Formation of a time (temporal) crystal

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It’s a crystal arranged in time according to a March 8, 2017 University of Texas at Austin news release (also on EurekAlert), Note: Links have been removed,

Salt, snowflakes and diamonds are all crystals, meaning their atoms are arranged in 3-D patterns that repeat. Today scientists are reporting in the journal Nature on the creation of a phase of matter, dubbed a time crystal, in which atoms move in a pattern that repeats in time rather than in space.

The atoms in a time crystal never settle down into what’s known as thermal equilibrium, a state in which they all have the same amount of heat. It’s one of the first examples of a broad new class of matter, called nonequilibrium phases, that have been predicted but until now have remained out of reach. Like explorers stepping onto an uncharted continent, physicists are eager to explore this exotic new realm.

“This opens the door to a whole new world of nonequilibrium phases,” says Andrew Potter, an assistant professor of physics at The University of Texas at Austin. “We’ve taken these theoretical ideas that we’ve been poking around for the last couple of years and actually built it in the laboratory. Hopefully, this is just the first example of these, with many more to come.”

Some of these nonequilibrium phases of matter may prove useful for storing or transferring information in quantum computers.

Potter is part of the team led by researchers at the University of Maryland who successfully created the first time crystal from ions, or electrically charged atoms, of the element ytterbium. By applying just the right electrical field, the researchers levitated 10 of these ions above a surface like a magician’s assistant. Next, they whacked the atoms with a laser pulse, causing them to flip head over heels. Then they hit them again and again in a regular rhythm. That set up a pattern of flips that repeated in time.

Crucially, Potter noted, the pattern of atom flips repeated only half as fast as the laser pulses. This would be like pounding on a bunch of piano keys twice a second and notes coming out only once a second. This weird quantum behavior was a signature that he and his colleagues predicted, and helped confirm that the result was indeed a time crystal.

The team also consists of researchers at the National Institute of Standards and Technology, the University of California, Berkeley and Harvard University, in addition to the University of Maryland and UT Austin.

Frank Wilczek, a Nobel Prize-winning physicist at the Massachusetts Institute of Technology, was teaching a class about crystals in 2012 when he wondered whether a phase of matter could be created such that its atoms move in a pattern that repeats in time, rather than just in space.

Potter and his colleague Norman Yao at UC Berkeley created a recipe for building such a time crystal and developed ways to confirm that, once you had built such a crystal, it was in fact the real deal. That theoretical work was announced publically last August and then published in January in the journal Physical Review Letters.

A team led by Chris Monroe of the University of Maryland in College Park built a time crystal, and Potter and Yao helped confirm that it indeed had the properties they predicted. The team announced that breakthrough—constructing a working time crystal—last September and is publishing the full, peer-reviewed description today in Nature.

A team led by Mikhail Lukin at Harvard University created a second time crystal a month after the first team, in that case, from a diamond.

Here’s a link to and a citation for the paper,

Observation of a discrete time crystal by J. Zhang, P. W. Hess, A. Kyprianidis, P. Becker, A. Lee, J. Smith, G. Pagano, I.-D. Potirniche, A. C. Potter, A. Vishwanath, N. Y. Yao, & C. Monroe. Nature 543, 217–220 (09 March 2017) doi:10.1038/nature21413 Published online 08 March 2017

This paper is behind a paywall.

An easier and cheaper way to make: wearable and disposable medical tattoolike patches

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A Sept. 29, 2015 news item on ScienceDaily features an electronic health patch that’s cheaper and easier to make,

A team of researchers has invented a method for producing inexpensive and high-performing wearable patches that can continuously monitor the body’s vital signs for human health and performance tracking. The researchers believe their new method is compatible with roll-to-roll manufacturing.

The researchers have provided a photograph of a prototype patch,

Assitant professor Nanshu Lu and her team have developed a faster, inexpensive method for making epidermal electronics. Cockrell School of Engineering

Assitant professor Nanshu Lu and her team have developed a faster, inexpensive method for making epidermal electronics. Cockrell School of Engineering

A University of Texas at Austin Sept. 29, 2015 news release (also on EurekAlert), which originated the news item, provides more details,

Led by Assistant Professor Nanshu Lu, the team’s manufacturing method aims to construct disposable tattoo-like health monitoring patches for the mass production of epidermal electronics, a popular technology that Lu helped develop in 2011.

The team’s breakthrough is a repeatable “cut-and-paste” method that cuts manufacturing time from several days to only 20 minutes. The researchers believe their new method is compatible with roll-to-roll manufacturing — an existing method for creating devices in bulk using a roll of flexible plastic and a processing machine.

Reliable, ultrathin wearable electronic devices that stick to the skin like a temporary tattoo are a relatively new innovation. These devices have the ability to pick up and transmit the human body’s vital signals, tracking heart rate, hydration level, muscle movement, temperature and brain activity.

Although it is a promising invention, a lengthy, tedious and costly production process has until now hampered these wearables’ potential.

“One of the most attractive aspects of epidermal electronics is their ability to be disposable,” Lu said. “If you can make them inexpensively, say for $1, then more people will be able to use them more frequently. This will open the door for a number of mobile medical applications and beyond.”

The UT Austin method is the first dry and portable process for producing these electronics, which, unlike the current method, does not require a clean room, wafers and other expensive resources and equipment. Instead, the technique relies on freeform manufacturing, which is similar in scope to 3-D printing but different in that material is removed instead of added.

The two-step process starts with inexpensive, pre-fabricated, industrial-quality metal deposited on polymer sheets. First, an electronic mechanical cutter is used to form patterns on the metal-polymer sheets. Second, after removing excessive areas, the electronics are printed onto any polymer adhesives, including temporary tattoo films. The cutter is programmable so the size of the patch and pattern can be easily customized.

Deji Akinwande, an associate professor and materials expert in the Cockrell School, believes Lu’s method can be transferred to roll-to-roll manufacturing.

“These initial prototype patches can be adapted to roll-to-roll manufacturing that can reduce the cost significantly for mass production,” Akinwande said. “In this light, Lu’s invention represents a major advancement for the mobile health industry.”

After producing the cut-and-pasted patches, the researchers tested them as part of their study. In each test, the researchers’ newly fabricated patches picked up body signals that were stronger than those taken by existing medical devices, including an ECG/EKG, a tool used to assess the electrical and muscular function of the heart. The team also found that their patch conforms almost perfectly to the skin, minimizing motion-induced false signals or errors.

The UT Austin wearable patches are so sensitive that Lu and her team can envision humans wearing the patches to more easily maneuver a prosthetic hand or limb using muscle signals. For now, Lu said, “We are trying to add more types of sensors including blood pressure and oxygen saturation monitors to the low-cost patch.”

Here’s a link to and a citation for the paper,

“Cut-and-Paste” Manufacture of Multiparametric Epidermal Sensor Systems by Shixuan Yang, Ying-Chen Chen, Luke Nicolini, Praveenkumar Pasupathy, Jacob Sacks, Su Becky, Russell Yang, Sanchez Daniel, Yao-Feng Chang, Pulin Wang, David Schnyer, Dean Neikirk, and Nanshu Lu. Advanced Materials DOI: 10.1002/adma.201502386 First published: 23 September 2015

This paper is behind a paywall.