Symposium SB08: Smart and Living Materials for Advanced Engineering Systems

Christoph Tondera, Leibniz Institute of Polymer Research Dresden

Multifunctional Conductive Hydrogels for Next Generation Bioelectronics

Written by Ethan To

The integration of electronic devices with biological tissue faces challenges due to mismatched mechanical and functional properties. While mechanical compatibility has seen progress, bridging the functional gap remains largely unexplored. To address this challenge, Dr. Christoph Tondera and his team at the Leibniz Institute of Polymer Research Dresden are developing a new class of conductive metamaterials that mimic and enhance the natural extracellular matrix. These materials combine the electroconductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) with sulfated/sulfonated polymer hydrogels (SSPH), creating a semi-interpenetrating network with tunable electrical and biomolecular properties. The PEDOT:SSPH system enables precise electrical stimulation, controlled molecule delivery, and biomolecular sensing. In his exciting talk, Dr. Tondera demonstrates the versatility of these materials by creating hydrogel-based sensors and inducing blood vessel-like structures in 3D cell cultures. This innovation pushes the boundaries of bioelectronics, paving the way for advanced tissue interfaces that seamlessly stimulate, sense, and interact with biological systems.

Symposium NM01: Nanotubes, Graphene and Related Nanostructures

Atul Sharma, Tufts University 

Multiplex Sensing Platform for Predictive Biomarkers in Vascularized Composite Allografts using Porous Laser-Engraved Graphene 
Written by In Young Park 

Vascularized composite allotransplantation (VCA) offers a promising solution for severe tissue deficits by transplanting vascularized human body parts comprising multiple tissue types, such as skin, muscle, bone, and nerves. However, acute rejection within the first eight days post-transplant remains a significant challenge, and current invasive monitoring methods are limited by sampling errors. This work introduces a low-cost, portable, flexible multiplex sensing platform using porous laser-engraved graphene (PLEG) electrodes to noninvasively monitor predictive biomarkers like interleukin-6 (IL-6), lactate, and pH. PLEG electrodes were fabricated via laser-induced carbonization (LIC) on polyimide, offering high surface area, conductivity, and sensitivity. IL-6 and lactate sensors were functionalized with Prussian blue, gold nanoparticles, and monoclonal antibodies or lactate oxidase, while pH sensing utilized a polyaniline (PANI) composite. Characterized using Raman spectroscopy, FTIR, XRD, and SEM, the sensors demonstrated high accuracy in detecting biomarker levels in buffer, interstitial fluid, porcine blood, and serum samples, achieving significant sensitivities. Validation against commercial ELISA and lactate kits showed strong correlations. Testing on swine VCA models confirmed the sensors’ ability to track post-surgical inflammation, ischemia, and rejection, aligning with clinical observations. This innovative platform provides a scalable, versatile tool for real-time, site-of-care VCA monitoring and management. 

Symposium SB01: Electrifying Biomaterials—Frontiers of Biohybrid Devices

John Zimmerman, Harvard University

Biohybrid Thin Film Models of Cardiac Output

Written by Ethan To

Microphysiological systems (MPS) are revolutionizing cardiac disease modeling by mimicking the heart’s native microenvironment with tissue-engineered devices. John Zimmerman from Harvard University highlights an innovative adaptation of muscular thin film (MTF) platforms to replicate cardiac function, mimicking the helical myofibril architecture of the left ventricle for efficient fluid pumping. Zimmerman demonstrates the development of angled tissue-engineered cantilevers to model the heart's twisting motion and measured fluid flows using particle imaging velocimetry (PIV) as an analog for cardiac output. By identifying optimal angles for maximal thrust through experimental and computational methods, this research bridges the gap between in vitro and clinical measurements. This approach integrates computational fluid dynamics with high-throughput screening, offering a simplified yet powerful platform to study cardiac health and disease. Overall, this work represents a significant step toward more realistic cardiac models with the potential to improve our understanding and treatment of the cardiovascular system.

Symposium CH06: Exploring Fast and Ultrafast Dynamics of Matter with Electrons and Photons

Sheng Hung Lee, Michigan State University

Temperature-Dependent Recombination Dynamics of Photocarriers in CsPbBr₃ Microcrystals Revealed by Ultrafast Terahertz Spectroscopy

Written by Andrew M. Fitzgerald

With a focus on CsPbBr₃, Sheng Hung Lee from Michigan State University studied the temperature-dependent recombination dynamics of photocarriers in the microcrystalline material using ultrafast terahertz spectroscopy. This work provides valuable insights into the behavior of photoexcited charge carriers in this promising inorganic perovskite. Lee observed that terahertz photoconductivity decays faster as pump fluence increases and temperature decreases, with decays under 10 ps dominating at 4 K. A nonlinear recombination model suggests that Auger scattering governs the fast decay at 77 K, while radiative recombination is the primary mechanism at 4 K. This transition highlights the interplay of different recombination pathways under varying conditions. Spectroscopic analysis showed a Drude-like photoconductivity response at all delays, but the inclusion of a Lorentz component, attributed to an exciton resonance above the band edge, was necessary to fully describe the data. The coexistence of excitons and free charge carriers significantly influences recombination dynamics, as the absorbed photon density exceeds the free carrier density. This study strengthens the understanding of photocarrier dynamics in CsPbBr₃ and further demonstrates its potential for applications in optoelectronics and energy devices.

Symposium EN11: Nitrogen-doped Carbon—From Fundamental Understanding to Applications in Electrochemical Devices

Wenyu Zhong, University of New South Wales 

Tunable Electrocatalytic CO2 Reduction Products on Fluorine-Engineered Iron Single Atom Catalysts 
Written by In Young Park 

The overconsumption of fossil fuels has created an urgent need for sustainable energy solutions, with electrochemical CO₂ reduction reaction (CO₂RR) emerging as a promising pathway to achieve carbon neutrality. Single-atom catalysts (SACs) have gained attention for their maximized atom utilization, design feasibility, and stability. This work demonstrates how fluorine (F) doping in iron-nitrogen-carbon (Fe-N-C) SACs can tune CO₂RR product distribution. By introducing F atoms either into carbon atoms or directly bonded to Fe, catalytic selectivity is altered, enabling enhanced carbon monoxide (CO) production or steady 1:1 syngas generation over a wide potential range. These changes, yielding a current density of up to 36 mA/cm² at -0.6 V in a flow cell setup, were characterized by in situ Fourier transform infrared (FT-IR) spectroscopy, X-ray absorption spectroscopy (XAS), and density functional theory (DFT) calculations, revealing how different types of F doping modifies the electronic structure and energy barriers at the iron (Fe) atomic center. This study highlights the flexibility of SAC design in tailoring CO₂RR performance, advancing catalyst development for sustainable applications. 

Symposium CH06: Exploring Fast and Ultrafast Dynamics of Matter with Electrons and Photons

KM Ashikur Rahman, Wesleyan University

Extended Time-Resolved Terahertz Spectroscopy for Photovoltaic Material Analysis

Written by Andrew M. Fitzgerald

KM Ashikur Rahman from Wesleyan University has worked to improve time-resolved terahertz spectroscopy (TRTS) to analyze the charge carrier dynamics of photovoltaic materials more comprehensively. The new approach that Rahman developed extends the TRTS observation window from the typical nanoseconds to hundreds of microseconds, allowing for more insights into the long-lived charge carrier processes that are essential for improving photovoltaic performance. TRTS, which uses terahertz waves generated by femtosecond lasers to probe transient conductivity, faces temporal limitations due to physical stage constraints, limited its observation window to approximately 2 ns. Rahman’s upgraded setup, incorporating electronic synchronization and an interchangeable diode laser, significantly increases the observation window to 30 microseconds and allows for bigger-picture analysis of surface and bulk carrier recombination processes. This extended timeframe captures longer-lived decay dynamics, providing more information about how charge carriers move and recombine in the sample material. Rahman tested the new setup on silicon wafers, benchmarking their results against known data. Future studies will focus on perovskite and organic photovoltaic materials, with planned upgrades to include an Nd:YAG nanosecond laser for finer resolution.

Symposium X—MRS/The Kavli Foundation Frontiers of Materials

Deji Akinwande, University of Texas at Austin

Unconventional Applications of Atomic Materials from Nonvolatile Electronics to Wearable Health and Ion Transport

Written by Sophia Chen

So-called two-dimensional (2D) materials, which consist of a single layer of atoms, offer many desirable properties for use in electronics, according to Deji Akinwande of the University of Texas at Austin. Akinwande made the case for this emerging category of materials during his Symposium X talk on Monday, December 2, titled “Unconventional Applications of Atomic Materials from Nonvolatile Electronics to Wearable Health and Ion Transport.” He presented research on the use of these materials in applications ranging from nanoelectronics to bioelectronics to energy.

To give the audience an intuitive conception of these materials, Akinwande likened 2D materials to a single sheet of paper in a stack. “In the x-y plane, they're very strongly bonded…But out of the plane, they're very weak,” he explained. These materials, removed from a stack one sheet at a time, have already proven useful in commercial applications. Examples of 2D materials include graphene, found in pencil lead, hexagonal boron nitride, found in makeup, and molybdenum disulfide, which is used as a dry lubricant in vehicles.

Akinwande first discussed the application of 2D molybdenum disulfide (MoS₂) for building a new type of computer known as a neuromorphic computer. The architecture of a neuromorphic computer emulates the human brain, where information is encoded and transported by “neurons” that connect to each other via “synapses” in imitation of human brain biology. This is in contrast to typical computers used today, which store its memory separately from where it computes, known as von Neumann architecture. Proponents of neuromorphic computers say that these machines offer higher energy efficiency than conventional computers, which could help solve the growing energy footprint of information technology.

Akinwande’s research involved developing the MoS₂ as a material for a memristor, which is a component of a neuromorphic computer for storing and computing data. The memristor cycles between two different resistances like a fast switch. As a thin crystalline material, MoS₂ tends to have fewer defects than metal oxides, which are the currently most popular material for memristors. Akinwande also said that the engineering of MoS₂ memristors has increased the number of times they can cycle from hundreds to millions. (See also: https://www.nature.com/articles/s41565-020-00789-w and https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202406703 )

He also discussed projects involving using 2D materials for electrodes in wearable health technology. These technologies make use of the fact that the human body is full of ions, which means you can measure voltages and currents and resistances in the human body correlated with human health.

These graphene electrodes, known as electronic tattoos, are thinner than other materials for wearable electrodes, such as thin metal: electronic tattoos. This makes it conform better to the skin, improving the signal-to-noise ratio. In addition, they designed the tattoos so that the wearer does not feel their presence. They performed a demonstration where they placed the graphene tattoo on a person’s eyelids to measure EOG, the electrical signal that emanates from your eyes. From their studies, “we can conclude that the graphene gives comparable signal fidelity and in some cases even superior signal fidelity to the commercial standard,” he said. They have also used these electrodes to measure blood pressure. Unlike the standard cuff, their wearable device can measure blood pressure with “every beat of the heart,” he says, leading to about 100,000 data points per day.

Akinwande ended his talk discussing the use of 2D materials in fuel cells. Strategies include mixing the 2D materials to create semi-permeable membranes in the cells which allow for proton conduction inside the cell while blocking undesired reactants.

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 MT04: Next-Generation AI-Catalyzed Scientific Workflow for Digital Materials Discovery

Tian Xie, Microsoft Research

MatterGen: A Generative Model for Inorganic Materials Design

Written by Jun Meng

Generative AI is redefining the boundaries of materials science. Tian Xie from Microsoft Research introduced MatterGen, a generative model that generates stable, diverse inorganic materials across the periodic table and can further be fine-tuned to steer the generation towards a broad range of property constraints.

The process involves gradually refining atom types, coordinates, and lattice structures, guided by property constraints such as symmetry, electronic, or mechanical properties. MatterGen’s ability to fine-tune outputs with labeled datasets enables multi-property optimization, a game-changer for challenges like designing supply-chain-friendly magnets without rare or expensive elements.

Xie showcased MatterGen’s ability to outperform prior generative models: generated materials are over twice as likely to be novel and stable and more than 15 times closer to the local energy minimum. The model's versatility was demonstrated with applications like phase transitions in magnesium oxide (MgO) and phonon dispersion in zinc selenide (ZnSe).

MatterGen marks a leap forward in accelerating high-throughput materials discovery, offering an exciting future for targeted materials design in fields like energy storage, catalysis, and magnetics.

Symposium NM01: Nanotubes, Graphene and Related Nanostructures

Masafumi Inaba, Kyushu University

Response Properties of NO₂ Gas Sensors Based on Ambipolar Carbon Nanotube FETs with Various Accumulation Amount 
Written by In Young Park 

Carbon nanotubes (CNTs) have great potential for gas sensors due to their large surface area and sensitivity to charge differentiation, yet the gas-response mechanism remains poorly understood, limiting device customization. Masafumi Inaba and his research team focus on nitrogen dioxide (NO₂) gas sensing using ambipolar CNT-based field-effect transistors (CNT-FETs) to investigate the gas-response mechanism at three key points: the CNT channel, CNT/metal electrode contact, and CNT/CNT junctions. CNT-FETs were fabricated using a back-gate structure and dielectrophoretically (DEP) assembled TUBALL CNTs with a semiconducting purity of over 98%, enabling precise control of CNT accumulation. Devices with low CNT amounts showed two distinct responses: a steady current shift in the hole-conduction region due to channel potential modulation and an abrupt decrease in transconductance in the electron-conduction region caused by Schottky barrier modulation. Devices with larger CNT amounts exhibited network-like structures with increased current in both conduction regions, attributed to reduced resistance at CNT/CNT X-type junctions during NO₂ adsorption. This was confirmed by observing smaller gate voltage shifts and larger decreases in current. High-speed NO₂ detection and recovery were achieved, with adsorption/desorption rates varying by sensing region. By linking local CNT structure to catalytic behavior using time constants and selectivity mapping, this study provides critical insights for designing high-performance CNT-based gas sensors. 

Symposium NM05: Structural Control and Design of 2D Layered Materials and Heterostructures Toward Novel Functionalities

Masaki Yamamoto, Murata Manufacturing Co., Ltd.

Synthesis and Characterization of Amino-Functionalized Ti3C2 MXene with Extremely High Conductivity

Written by Andrew M. Fitzgerald

Masaki Yamamoto from Murata Manufacturing Co., Ltd. developed a highly conductive amino-functionalized Ti₃C₂ MXene with a record-breaking conductivity of approximately 4,000 S/cm. This a significant advancement in research being done on the surface chemistry of MXenes, which are a family of 2D transition metal carbides, nitrides, and carbonitrides that have found use in many different electronic applications. MXenes are important because their properties can be “tuned” by making slight changes to their chemical composition. Researchers have found that modifying their surfaces could allow for a more precise ability to do so. Amino-functionalization, in particular, offers benefits such as enhanced oxidation resistance, improved dispersibility in organic solvents, and new reactive sites for biomolecules, polymers, and other organic molecules. However, traditional methods using silane coupling agents (SCAs) face challenges, including self-polymerization that reduces the material's conductivity. Yamamoto overcame these limitations by introducing amino groups using phosphonic acid as a ligand. The resulting material has exceptional electrical properties. This breakthrough opens new possibilities for MXenes in high-performance applications, including energy storage, sensors, and electronic devices, where maintaining high conductivity is crucial to good performance. Future work aims to explore additional factors contributing to the material’s enhanced conductivity and further optimize MXene surface modifications.