Symposium X—MRS/The Kavli Foundation Frontiers of Materials

Tonio Buonassisi, Massachusetts Institute of Technology

Finding a Path from “Promise” to “Performance”—Toward Realizing Novel Materials Predicted via Generative AI

Written by Sophia Chen

It’s all the rage: artificial intelligence—from generative models to automated laboratories—will help researchers find novel and useful materials faster. But Tonio Buonassisi, a mechanical engineer at Massachusetts Institute of Technology, knows that to get to that place, the field has its work cut out for it.

“This is not your normal tech-vangelist talk where I'm going to go up and show you how great AI is and how autonomous labs are going to rock the world,” said Buonassisi during Thursday’s Symposium X. “Yes, I do believe that. And I also believe that the path to getting there is a hard one.”

In Thursday’s Symposium X, titled “Finding a Path from ‘Promise’ to ‘Performance’—Toward Realizing Novel Materials Predicted via Generative AI,” Buonassisi outlined his perspectives on the state of automation and automated materials discovery, as well as the role of AI in these processes.

Buonassisi focused on pragmatic challenges. The adoption of AI will involve growing pains, he says. He described the trajectory as curve, where the field will hit what feels like unproductive bottlenecks: “You're putting in a lot of investment and not getting out much return. So this talk is about a lot of that part of the curve, and creating community around getting us over that part.”

Currently, the materials community has already adopted automation in a variety of settings. Scientists at the University of Liverpool, for example, use co-bots, or robots designed to work in close proximity to humans. Researchers at Boston University have also developed a robot arm that coordinates with 3D printers to manipulate materials samples.

Working at Singapore’s Agency for Science, Technology, and Research, Buonassisi started a program known as Accelerated Materials Development for Manufacturing, where they adopted a method known as “islands of automation.” To do this, instead of aiming to create a fully autonomous materials discovery process, they focused on accelerating “specific parts of the process and […] strategically targeted those points in the workflow that require more time, or that suffer from irreproducibility due to human factors,” he said.

The adoption of AI, which largely comprises models known as neural network, presents many challenges for the field, Buonassisi described in the talk. For example, the field needs to better identify which problems are most appropriate for autonomous or automated systems. On top of that, they need to increase the odds that experiments can actually synthesize and test an AI-predicted material. He listed several practical questions in the use of AI: for example, how should researchers choose a neural network architecture? How do they select, obtain, and validate training data? How should researchers represent materials to the neural network? How do they diagnose issues when things are going wrong? How should they select candidate materials that the neural network generates? How should they quantify the uniqueness or the novelty of the AI-generated materials? “These are […] examples of some of the things that, in my opinion, would yield truly high-impact papers, if you're a graduate student, postdoc, or early-stage career professor,” said Buonassisi. Using AI to discover unusual materials presents a particular challenge, he said. Experts have concluded that they would probably not have been able to predict the cuprates, high-temperature superconductors, given today’s AI tools and data prior to 1987 when researchers discovered the material.

The field should also critically examine the social structures that drive materials research, Buonassisi said. Individuals face different incentives than those of academia as an institution, and that can present a tension. While Buonassisi says this is a systemic problem and does not promise any solutions, he proposes a different academic structure in which the total number of students and postdocs are reduced. As they become more senior, they begin to manage “undergraduate researchers and staff who can augment their capabilities, who can complement some of their weaknesses in computation automation, in domain expertise,” he said.

Symposium X—MRS/The Kavli Foundation Frontiers of Materials features lectures aimed at a broad audience to provide meeting attendees with an overview of leading-edge topics.

Symposium SB11: Bio-based and Biomimetic Polymers in Soft Robotics

John A Rogers, Northwestern University

Flexible Electronic Skin for Sensing and Haptic Actuation

Written by Kazi Zihan Hossain

John Rogers and his group from Northwestern University have been pioneering flexible electronics that can be attached to human skin for various medical purposes. Traditional rigid electronics can be made flexible through geometrical manipulation such as thinning, incorporating wavy structures, or materials innovation. Instead of limiting the technology’s development to sensing body activity, these epidermal electronics also possess therapeutic potential. Skin-like wireless electronics have been used to monitor the vital health signs of babies in developing countries where adequate resources were not available. Soft electronics attached to the throat can be used to monitor the swallowing and vocal activity of stroke patients instead of bulky and cumbersome wired instruments, which is crucial for personalized rehabilitation. Haptic feedback integrated into wearables can assist prosthetic control and sensory substitution for people with nerve problems. The latest efforts have been made to attach flexible electronics to different positions of the human body and expand the haptic feedback to incorporate thermal feedback and multimodal systems to contribute to better healthcare systems.

Symposium MT03: Machine Learning Methods, Data and Automation for Sustainable Electronics

Victor Fung, Georgia Institute of Technology

Physics-Informed Pre-training of Graph Neural Networks for Materials Property Predictions

Written by Kazi Zihan Hossain

Materials scientists have used machine learning models and artificial intelligence (AI) to predict the properties of different materials. Traditional approaches require individual models and re-training for every different system to predict different properties. A model trained to predict a specific property can not be used to predict another property of the materials. To overcome this issue and develop a single model that can be used to predict different properties of materials, Victor Fung from the Georgia Institute of Technology has presented a Graph Neural Network (GNN) approach. In this technique, the composition and structure of a material can be encoded into a graph so that the properties of the materials can be related to the structure. Traditionally, GNN approaches work well when enough data is available to train the model, which may not be feasible from a material science perspective. Therefore, Fung and colleagues used the transfer learning technique to pre-train the model from a large dataset and then used the model to tune the properties of the materials. Different models, such as Crystal Graph Convolutional Neural Networks (CGCNN) and TorchMD-Net, were used to predict the properties of the materials, where the latter performed well under denoising scenarios.

Symposium EN07: Thermal Transport and Energy Conversion

Takahiro Baba, National Institute of Materials Science (NIMS), Japan

Thermal Diffusivity Measurement of Thin Films by Fourier Transform Thermo-Reflectance Method under Front Heat-Front Detect Configuration

Written by Kazi Zihan Hossain

Thermal conductivity measurement is crucial for nanoscale materials. In the traditional approach, thermal diffusivity is determined from an analytical solution after single pulse heating to obtain a thermos-reflectance signal; however, the actual thermos-reflectance signal requires periodic pulse heating. Takahiro Baba from the National Institute of Materials Science, Japan, and colleagues have developed a novel technique using the Fourier series to solve an exact analytical solution to express temperature response after heat diffusion from periodic pulse heating. A laser beam is incident on a 100-nm thick platinum thin film and collected with the photodetector when a pulse pump beam is used on the rear side of the thin film. The proposed technique could measure the thermal diffusivity and also exclude the effect of time delay. The technique is expected to work for more complicated samples like multi-layered thin films.

Symposium X—MRS/The Kavli Foundation Frontiers of Materials

Ying Diao, University of Illinois at Urbana-Champaign

Printing Polymer Electronics for Sustainable Earth and Habitable Mars

Written by Sophia Chen

During Ying Diao’s talk on Wednesday, she showed an image of a printer roll—not of paper, but semiconductors. “Organic electronics can be made […] akin to the way we make newspapers,” she said. These methods, which fall under the technique of 3D printing, promise cheap, high-throughput, and on-demand production. Consequently, researchers are investigating methods and materials for applications ranging from solar power to agriculture. Diao discussed the state of the technology in her talk, titled “Printing Polymer Electronics for Sustainable Earth and Habitable Mars.”

For their printed electronics, Diao’s laboratory uses conjugated polymers. While conjugated polymers are inherently semiconductors, when doped, these organic molecules can be as conductive as metals. Such organic molecules are already used in wearable electronics such as the organic light-emitting diodes in smartwatches. Researchers can modulate these materials’ conductivity over 14 orders of magnitude, she said. They have also recently used three-dimensional conjugated polymers to create structural color, where an object’s color derives from light interference with microscale or nanoscale structures. (Many animals, such as butterflies, exhibit structural color.) They also discover and design new materials using both physics-based approaches as well as artificial-intelligence-aided approaches.

Diao believes the future generation of organic electronics materials will be semiconductors that are chiral. The structure of chiral materials exhibits either right-handedness or left-handedness, meaning they lack mirror symmetry. (A helix is an example of a chiral structure.) Chiral structures are common in nature, such as in chlorophyll. The chlorophyll’s chirality makes charge transport much more efficient during photosynthesis. Chiral organic semiconductors could offer similar advantages. In recent work, her team found that they could create helical organic semiconductors through 3D printing. The chirality emerged by adjusting the flow rate and concentration of the material during printing.

Notably, when Diao and her group analyzed the material, they found that it exhibited chirality on multiple scales—from the micron-scale to the nanometer-scale. “We have a helix within a helix within a helix,” she said. This nested helicity also occurs in collagen.

Chiral organic semiconductors would be well-suited for various next-generation electronics, said Diao. For example, when hit with light, chiral molecules sustain excitons longer than planar molecules, a quality useful for solar cells.  They could also be useful for spintronics.

Diao ended her talk discussing a prototype device using printed electronics to aid agriculture. They designed the device with futuristic missions for inhabiting Mars in mind. The device consists of a stretchable sensor for monitoring the growth rate for plants. Printed electronics are promising for extraterrestrial applications because they are lightweight and high performance, she said.

Symposium X—MRS/The Kavli Foundation Frontiers of Materials features lectures aimed at a broad audience to provide meeting attendees with an overview of leading-edge topics.

First time at an MRS Meeting!

 

Blogger: Edie Green

Symposium SB11: Bio-Based and Biomimetic Polymers in Soft Robotics

Michael Dickey, North Carolina State University

Ultra-Tough Ionogels for Stretchable Ionic Devices 

Written by Kazi Zihan Hossain

Gels are crosslinked polymers swollen with liquid. They are considered soft and flexible materials that break easily when they experience significant stretching. Soft materials like rubber bands are very stretchy and soft, while glasses are stiff and rigid and can experience very high strain but are not stretchable. Tough materials fall between them, and they can survive both high stress and high strain. Gels need to have both elastic networks and energy-dissipating networks to become tough materials. Michael Dickey from North Carolina State University has presented several revolutionary examples of such tough gels. Polyacrylamide and polyacrylic acid were copolymerized by introducing ionic liquid to induce phase separation and fabricate ultra-tough ionic gel with a facile approach. Gels can be made tough by also introducing a double network or introducing noncovalent crosslinks. Lastly, they have also presented another facile technique where liquid metal (eutectic gallium indium) was introduced to initiate free radical polymerization without the use of a traditional molecular initiator.

Symposium MF01: Advances in Polymer-based Soft Matter for Additive Manufacturing

Shangsi Chen, Zhaohe Xu, and Min Wang, The University of Hong Kong

3D Printed core-shell structured scaffolds with NIR-Triggered dual release for cancer therapy and uterine tissue regeneration

Written by Swati Suman

Gynecologic cancers and uterine fibroids often result in uterus dysfunction and hence result in female infertility. The hydrogel/poly(L-lactide-co-trimethylene carbonate hormone estradiol (E2)-containing polydopamine (PTMC-PDA@E2) coating layer significantly enhanced mechanical properties and strengthened the uterus better than the native tissues. The chronological release of the E2 over a certain period (28 days) promotes uterine tissue regeneration. This novel Gel- anticancer drug doxorubicin hydrochloride (DOX)/PTMC-PDA@E2 core-shell scaffolds have shown their potential for postoperative management in female patients. The coating layer protected the Gel-DOX core from rapid biodegradation and thus inhibited the burst release of DOX.

Symposium EL02: Towards Atomically Precise Colloidal Materials for Conventional and Quantum Optoelectronics

Written by Swati Suman

Jennifer Hollingsworth and Eric Bowes, Los Alamos National Laboratory

Precision colloidal synthesis: How far can it take us in realizing advanced quantum light sources?

Core/shell heterostructure of semiconductor quantum dot provides a better way to explore the limits of controlling quantum optical properties. Control over heterostructure at the nanoscale level provides better band structure, which affects the photoluminescence. Introducing a hole trap at the LnP/CdSe QDS interface releases two color excitonic emissions. The different nano-heterostructure systems reveal the opportunity for achieving designed quantum optical properties.

Victor Klimov, Los Alamos National Laboratory

Engineered colloidal quantum dots as universal optical gain media for solution and solid-state lasers and laser diodes

Laser technologies can be enhanced using colloidal quantum dots. The scalability and inexpensive chemical techniques used to synthesize QDs make them more attractive and prominent to work on. Faster Auger recombination can be removed using meticulously engineered hetero-QDs. The researcher has also employed compositional grading of QDs interior to smoothen charge carrier confinement potential, thereby suppressing the strength of individual Auger transition. This engineered QD shows longer optical gain lifetimes while maintaining strong 3D confinement.

Symposium SB02: Charge Carrier Transport in Organic and Organic-Inorganic Hybrid Materials

John Anthony, Tanner Smith, Karl Thorney, and Dean Windemuller, University of Kentucky

Synthesis and functionalization of new chromophores for organic electronics and photonics

Written by Swati Suman

Organic electronics has gained much attention due to its viability and range of applications in optoelectronics. However, it requires optimization of both core chromophore and interaction in solid states. The research team explored the synthesis and implementation of large chromophores fused ring aromatic compounds to enhance photonics properties. The researchers have developed a process to grow large aromatic systems that have absorbance in the near-infrared region. With electronic coupling within chromophores, the researchers developed singlet fission chromophores that yield quintet states. Along with tuning the functional group on other systems, using C-H-π interaction reduces disorders and greatly impacts charge transport. The researchers have established long life by new reaction pathways that alter reaction with oxygen or dimerization.