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In this podcast episode, MRS Bulletin’s Sophia Chen interviews Prof. Esma Ismailova and graduate student Marina Galliani from Mines Saint-Etienne about their work toward creating biocompatible, eco-friendly materials for wearable electronics. For this particular project, they developed a conducting material based on a commercial polymer known as PEDOT-PSS, in a water-based solution. They combined it with various solvents to tune the electrical conductivity, which is dependent on the shape and structure of the polymers in the material as they dry. The researchers tested the material’s conductivity on several substrates, including paper-based substrates and textiles. To make the material printable, they also needed to tune the material’s viscosity. Because the material relies on inkjet printers that are already commonly available, this material is relatively easy to incorporate into industrial processes. This work was published in a recent issue of APL Bioengineering. 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Rob Shepherd from Cornell University about an adaptive-responsive self-healing soft robotic system. Shepherd’s research team has developed waveguides made of self-healing polyurethane urea crosslinked with aromatic sulfide bonds. When this material is cut, relatively weak hydrogen bonds quickly form. Disulfide exchange then occurs and, although this takes longer than the formation of hydrogen bonds, results in much stronger bonding and so recovering much of the mechanical strength of the polymer. Light is transmitted down the waveguide and, when the material is cut or punctured, the signal is attenuated. The loss of signal can be acted on by the robot and it can change its pattern of movement until the strong disulfide bonds are formed. This self-healing material absorbs more light than previous versions of the polymer that couldn’t effect a chemical repair. This level of light absorption is actually useful as it makes the robot more sensitive to damage or deformation. This work was published in a recent issue of Science Advances. 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Jiahui Li, a graduate student at the University of Illinois Urbana-Champaign about designing structures out of gold nanoparticles. When the nanoparticle structure takes the shape of a pinwheel, different types of light interact with the structure differently due to its chirality. Different wavelengths might be transmitted depending on whether the light’s polarization is rotating clockwise or counterclockwise, which could make this structure useful for filtering light in optical applications. This work was published in a recent issue of Nature (https://doi.org/10.1038/s41586-022-05384-8).

In this podcast episode, MRS Bulletin’s Laura Leay interviews Robert Hovden from the University of Michigan and his graduate student Jonathan Schwartz on development of the freely available Tomviz platform (tomviz.org) that enables real-time three-dimensional (3D) visual analysis of materials. Building on the already existing Tomviz platform, Schwartz created new algorithms capable of pulling data from transmission and scanning electron microscopes, evolving the 3D image as the experiment progresses. This research is published in a recent issue of Nature Communications (https://doi.org/10.1038/s41467-022-32046-0). 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Tao Yang from the City University of Hong Kong in China who focuses on the innovative design of advanced structural materials. In the area of high-strength alloys, Yang’s research team looked specifically at how to stabilize nanoparticles at high temperatures. In an alloy of Ni59.9-xCoxFe13-Cr15Al6Ti6B0.1, Yang’s team achieved ultra-stable nanoparticles at 800–1000°C. They achieved this effect by tailoring the concentration of cobalt. While nanoparticles have already been seen to improve the strength of materials, Yang’s team has provided insight into how this can be achieved at high temperatures. This research is published in a recent issue of Nature Communications (https://doi.org/10.1038/s41467-022-32620-6).

In this podcast episode, MRS Bulletin’s Stephen Riffle interviews Alessandra Scagliarini, a professor of infectious disease at the University of Bologna, and Beatrice Fraboni, a professor of physics at the Department of Physics and Astronomy at the University of Bologna, about their electrical transistor assay that quantifies SARS-CoV-2 for antibodies. The purpose is to determine vaccine efficacy over time. The device is built with the semiconducting material poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The material not only transfers ion signals into electronic signals, but also amplifies it. Without neutralizing antibodies, the virus attacks the cells, causing both macro cracks as well as minor disruptions in the tight junctions of the cells, which the high sensitivity of this device is able to detect. This kind of data is an indirect way to assess whether patient samples have neutralizing antibodies. This work was published in a recent issue of Communications Materials (doi:10.1038/s43246-022-00226-6). 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Murat Onen, a postdoctoral researcher at the Massachusetts Institute of Technology, about analog deep learning that could help lower the cost of training artificial intelligence (AI). The programmable analog device stores information in the same place where the information is processed. The resistor’s main material is tungsten oxide, which can be reversibly doped with protons from an electrolyte material known as phosphosilicate glass, or PSG, layered on top of the tungsten oxide. Palladium is above the PSG layer, which is a reservoir for the protons when they are shuttled out of the tungsten oxide to make it more resistive. “When protons get in, it becomes more conductive. When the protons go out, it becomes less conductive,” says Onen. The resistance of this device responds in about 5 ns. This work was published in a recent issue of Science (doi:10.1126/science.abp8064).

In this podcast episode, MRS Bulletin’s Laura Leay interviews Monica Olvera de la Cruz of Northwestern University and her colleagues who gained insight into biochirality. By analyzing self-assembly for a series of amphiphiles, Cn-K, consisting of an ionizable amino acid [lysine (K)] coupled to alkyl tails with n = 12, 14, or 16 carbons, the researchers found the degree of ionization is what controls the shape. They incorporate this phenomenon into a membrane energetics model. Furthermore, their experimental techniques show that the nanoscale structure of the chiral assemblies can be continuously controlled by solution ionic conditions. The model moves researchers one step closer to building entire cells in the laboratory and could lead to the development of nanotechnology such as drug delivery and electronics. This research is published in a recent issue of ACS Central Science (https://doi.org/10.1021/acscentsci.2c00447).

In this podcast episode, MRS Bulletin’s Laura Leay interviews Sergey Artyukhin from the Istituto Italiano di Tecnologia and Louis Ponet, who is affiliated with both the Istituto Italiano di Tecnologia and Scuola Normale Superiore di Pisa about a topologically protected switching phenomena in ferroic materials. When a multiferroic crystal (GdMn2O5) is placed in a magnetic field at a very particular angle to a crystallographic axis, and the magnetic field is swept up and down twice, the system switches between four magnetic configurations. The interplay between the spin of the gadolinium and manganese ions leads to a unidirectional rotation of the spins and because this rotation is caused by the up-down sweep of the magnetic field, it can be thought of as a crankshaft. This four-state magnetoelectric switching emerges as a topologically protected boundary between different two-state switching regimes. While this magnetoelectric switching has only been observed in one multiferroic material, modelling can help predict other suitable materials from first principles. Eventually this could lead to new technology. This work was published in a recent issue of Nature (doi:10.1038/s41586-022-04851-6).

In this podcast episode, MRS Bulletin’s Laura Leay interviews Peter Gumbsch, who is affiliated with both the Karlsruhe Institute of Technology and the Fraunhofer Institute for Mechanics of Materials in Germany about gear-based mechanical metamaterials. The researchers offer a paradigm shift in design where—instead of choosing a material for a given application and compromising on materials properties—engineers can consider an adaptable metamaterial to build shape-morphing structures that can withstand any environment. Each gear is analogous to an atom except that whereas the properties of the bonds between atoms cannot be changed, the properties of the coupling between the gears can. This work was published in a recent issue of Nature Materials (doi:10.1038/s41563-022-01269-3).

Victor A. Rodriguez-Toro, a researcher in materials and devices and a science correspondent for MRS Bulletin, interviews Ayse Turak, Associate Professor of Engineering Physics and Director of the Centre for Emerging Device Technologies at McMaster University in Canada, about her group’s research in organic optoelectronics. Turak focuses her research on developing easy, versatile, and inexpensive methods of exploring and tuning interfaces, particularly in organic, perovskite and nanoparticle solar cells, light-emitting diodes, and sensors. Turak discusses her latest work in which her group controlled the reaction kinetics and slowed down the rate of perovskite formation by using diblock copolymer reverse micelle templating. “The slowed reaction,” they write in their article, “allows the use of an unconventional approach, mixing methylammonium iodide (MAI) and lead bromide (PbBr3) to produce pure methylammonium lead bromide MAPbBr3 [nanoparticles].” With this method, Turak’s group achieved two stable phases in a single solution. Turak also talks about challenges to using nanoparticles in devices for wearable electronics and the role of LiF interfaces for high-efficiency organic solar cells. She speculates on which type of optoelectronics will be preferred for commercialization. As an “out” lgbtq+ researcher in the materials science field, Turak provides insights into how universities and research centers can open the doors to help lgbtq+ scientists feel more integrated into the scientific community. She also provides advice to the new generation of researchers coming from different backgrounds representing diversity in science-technology-engineering-mathematics (STEM). 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Bin Ouyang of Florida State University about making a better cathode for lithium ion batteries. The current use of cobalt and nickel in their cathodes causes Li-ion batteries to contract in volume and degrade. Ouyang and his colleagues simulated and then fabricated new cathode materials that do not use cobalt or nickel and also degrade less after being charged and discharged. To achieve this, they found that they needed to design a material with disorder in its crystal structure. They found that replacing cobalt and nickel with vanadium and niobium leads to a battery with a small change of volume. The results provide a model for the further search of viable cathode materials to design lithium-ion batteries that are entirely made of solids. This study is published in Joules (doi:10.1016/j.joule.2022.05.018). 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews graduate student John Ahrens of Harvard University about challenges in bioprinting heart tissue. One challenge in particular is aligning the cells. Heart cells are narrow and rectangular in shape. In a natural heart, they line up in parallel to form aligned filaments. Those aligned filaments are built up into a larger tissue with more complex alignment. Cellular alignment correlates with heart function. The research team has programmed the bioprinter to make tissues that are aligned vertically, in a circular pattern, or in the shape of a chevron.  This study is published in Advanced Materials (doi:10.1002/adma.202200217). 

In this podcast episode, MRS Bulletin’s Laura Leay interviews Laura Rossi from Delft University of Technology (the Netherlands) and  Greg van Anders from the University of Michigan (USA) and Queen’s University (Canada) about advances they’ve made in colloidal preassembly in order to gain control in materials structure at a range of length scales. Through experiments and computer simulation, the researchers showed that particle interaction and particle shape can be decoupled through spherical confinement, which – when clustered – assembled differently than those observed in bulk assembly. This work was published in a recent issue of Science Advances (doi: 10.1126/sciadv.abm0548). 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Adam Kubec at Swiss startup XRNanotech and research team member Marie-Christine Zdora of the Paul Scherrer Institut about their proof-of-principle of an x-ray achromatic lens. The lens consist of a focusing diffractive and a defocusing refractive optical element that achieves imaging of a range of wavelengths without having to move the sample. The researchers used two different diffractive lenses, one made from nickel and one with gold. To fabricate the refractive lens, they used a nanoscale 3D printing technique known as two-photon polymerization. This work was published in a recent issue of Nature Communications (doi:10.1038/s41467-022-28902-8).

In this podcast episode, MRS Bulletin’s Stephen Riffle interviews Jennifer Gelinas, an assistant professor in the Department of Neurology and Institute for Genomic Medicine at Columbia University Irving Medical Center, and Dion Khodagholy, an associate professor in the Department of Electrical Engineering at Columbia University, about their ionic communication system for implantable devices. The system involves building a capacitor using water ions and biomolecules. With the placement of two conducting electrodes in the body and introduction of an alternating current, the tissue between the electrode will act as an electrolyte medium. Together, these two electrodes and their electrolyte medium form a capacitor that is capable of generating a detectable electrical field. The ionic communication device is fabricated with materials that have already been shown to be safe in the body, such as gold and a semiconducting plastic—poly(3,4-ethylenedioxythiophene)–polystyrenesulfonate or PEDOT:PSS. This work was published in a recent issue of Science Advances (doi:10.1126/sciadv.abm7851).    

In this podcast episode, MRS Bulletin’s Laura Leay interviews Michael Dickey from North Carolina State University about his work manipulating liquid gallium. When submerged in an aqueous solution, liquid gallium will form a sphere. When fed by gravity through a thin nozzle that is surrounded by aqueous solution, it will instead flow into the shape of a wire. Passing an electrical current through the liquid metal wire means that a magnetic field is created, which means the wire can be shaped using external magnets, following the Lorentz force. This research was published in a recent issue of the Proceedings of the National Academy of Sciences (doi:10.1073/pnas.2117535119).   

In this podcast episode, MRS Bulletin’s Laura Leay interviews Yang Yang and Yepin Zhao of the University of California, Los Angeles about a dual-function p-type soft interlayer they developed to enhance efficiency of charge transfer in organic solar cells. With the introduction of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the p-type material, the researchers are able to improve the efficiency of the device as well as change its optical distribution. One goal for such a device, they say, is to create a greenhouse that generates its own electricity. This study is published in ACS Nano (doi:10.1021/acsnano.1c09018). 

In this podcast episode, MRS Bulletin’s Sophia Chen interviews Kenjiro Fukuda from RIKEN in Japan and Masahito Takakuwa of Waseda University about a technique to connect integrated electronics while maintaining their flexibility. They demonstrated the method on two gold electrodes. To make the two pieces of gold bond, the researchers treated the gold with water vapor plasma. The researchers used this technique to electrically connect the gold electrodes of an organic photovoltaic to an organic light-emitting diode without adding significant thickness, thereby ensuring the flexibility of the device. This study is published in Science Advances (doi:10.1126/sciadv.abl6228). 

In this podcast episode, MRS Bulletin’s Stephen Riffle interviews Samuel Herberg from SUNY upstate medical university in Syracuse, New York about a new tool to study cell behavior. According to Herberg, culturing cells in an environment that reflects the materials properties of the human body can help reveal new insights into cell biology and mechanisms of disease. To do that, his research team has created a hydrogel using natural polymers. Through UV and chemically induced crosslinking, Herberg’s team is able to finely tune their hydrogel’s stiffness, which enables them to study diseases like primary open angle glaucoma, the world’s leading cause of vision loss. Their study is published in Frontiers in Cell and Developmental Biology (doi: 10.3389/fcell.2022.844342).