Author Archives: SAM

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In-person in HCI J 4 or on Zoom: https://ethz.zoom.us/j/68765823059

Sodium ion batteries: Opportunities and challenges

Eldho Edison (Multifunctional Materials — D-MATL)

Among the existing energy storage technologies, lithium-ion batteries (LIBs) have unmatched energy density and versatility. From the time of their first commercialization in 1991, the growth in LIBs has been driven by portable devices. In recent years, however, large-scale electric vehicle and stationary applications have emerged. These large-scale applications have put unprecedented pressure on the LIB value chain, resulting in the need for alternative energy storage chemistries.

The Sodium-ion battery (SIB) chemistry is one of the most promising “beyond-lithium” energy storage technologies. In this talk, the technological evolutions of both LIBs and SIBs, the key differences/similarities between the two battery chemistries and the prospects and challenges for the commercialization of SIBs will be presented. The research progress and the challenges of high-capacity alloying anodes for Sodium-ion batteries will be discussed.

Magnetic vortices: into the third dimension

Sebastian Gliga (Laboratory for Condensed Matter — PSI)

Vortices are familiar phenomena in fluids and gases, apparent for example in tornadoes, hurricanes, and whirlpools. Vortices also exist in ferromagnets, where they are characterized by a circulating in-plane magnetization structure. The resulting pattern leads to a very stable state whose study is motivated by both fundamental and technological interest.
Over the past decades, vortices have been extensively studied in thin-film structures, where the magnetization is accessible with two-dimensional imaging methods. Recently, the development of X-ray based magnetic nanotomography with a spatial resolution of 100 nm has enabled the non-destructive imaging of bulk magnetic structures. We have uncovered three-dimensional structures forming vortex loops corresponding to magnetic vorticity rings that are formally analogous to hydrodynamic vortex rings in fluids. Remarkably, we have also observed structures that have no counterparts in incompressible fluids: stable vortex loops intersected by magnetic singularities.

While vortices have been studied in bulk magnets since at least the 1970s, our results shed new light onto their rich physics and open possibilities for further studies of complex three-dimensional solitons, enabling the development of applications based on three-dimensional magnetic structures.

 

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Zoom: https://ethz.zoom.us/j/61014166756

Low-Dimensional Optoelectronics

Lukas Novotny (Photonics Laboratory – D-ITET)

To co-integrate photonics with electronics the length-scale of optical devices has to be reduced below the wavelength of light. To achieve this goal we interface optical antennas made of noble metals with low-dimensional materials, such as graphene, hexagonal boron-nitride (hBN) and transition-metal dichalcogenides (TMDs). Optical antennas enhance the interaction strength and boost the efficiency of low-dimensional optoelectronic devices.

In this talk I will describe different low-dimensional optoelectronic devices that we recently fabricated and characterized. These include 1) waveguide-integrated photodetectors based on MoTe2, 2) light-emitting devices based on inelastic electron tunneling, and 3) nonlinear phased array antennas for directional photon emission.

Six-axis multi-process additive manufacturing for implantable medical devices

Fergal Coulter (Complex Materials – D-MATL)

The presentation will focus on multi-axis additive manufacturing techniques for fabricating bio-hybrid implantable devices. Example objects are detailed, such as patient-specific prosthetic heart valves [1] and cellular macro-encapsulation devices. The design and fabrication of custom 3D printers and vision system hardware, required for their manufacture is also outlined.

Multi-material objects with unique properties are realised by combining multiple deposition techniques - direct ink writing, spray deposition, micro-jetting and/or thermoplastic pellet extrusion - with laser-based 3D scanning techniques. Examples include inflatable minimum energy structures containing bonded layers with differing levels of stress [2]; living bio-inks printed over the surfaces of complex multi-curved mandrels and selectively permeable membranes that are found to encourage cellular on-growth [3].

[1] Bioinspired Heart Valve Prosthesis Made by Silicone Additive Manufacturing in Matter 2019
[2] Production Techniques for 3D Printed Inflatable Elastomer Structures: Part II in 3DP&AM 2018
[3] Additive Manufacturing of Multi-Scale Porous Soft Tissue Implants That Encourage Vascularization and Tissue Ingrowth. Adv Healthcare Matr. 2021

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Zoom: https://ethz.zoom.us/j/66758737383

Magnetoelectric teleportation

Manfred Fiebig (Multifunctional Ferroic Materials – D-MATL)

Teleportation, the transfer of matter or energy between points in space without traversing the physical distance between them, is a common subject in science fiction. Aside from the fascination in propagation-less transfer of matter or energy, teleportation allows authors or filmmakers to dispose of the description of lengthy journeys or save the costs of depicting these. Teleportation has been realized in the quantum world, where it denotes the immediate transfer of the quantum state of an atom or photon through quantum-mechanical entanglement. In this expanded definition, it is a form of communication rather than spatial transformation, and restricted to atomic dimensions. In the macroscopic world, teleportation is believed to be nonexistent, however. Here I demonstrate that nevertheless, compounds with simultaneous magnetic and electric order, so-called multiferroics, permit a special form of teleportation.

Innovating Medical Materials

Inge K. Herrman (Nanoparticle Systems Engineering Laboratory – D-MAVT)

The well-controlled synthesis of nanoscale materials is arguably one of the most important achievements of material science in the past decades. With the push to simplify biomedical material designs, inorganic nanomaterials have regained interest. Especially metal and metal oxide nanomaterials have attracted significant attention due to the scalability and robustness of their synthesis and their tailorable composition and architecture. In the first part, I will present an approach to unite tissue adhesion, based on nano-bridging, with bioactivity for wound healing applications. Uniting these properties requires control over nanoparticle architecture and freedom of choice in materials. Liquid-feed flame spray pyrolysis (LF-FSP) fulfills these requirements, while offering scalable and sterile synthesis. By utilizing the versatility of LF-FSP, we have united the wound closure properties of bioglass with the anti-inflammatory properties of ceria in one nanoparticle hybrid system. By tailoring the architecture of the hybrid nanoparticles, temporal control of the material bioactivities can be achieved in order to optimally address the different phases of the wound healing cascade. In the second part of my presentation, I will briefly introduce a new adhesion concept based on mutually interpenetrating networks as a new route to high performance tissue adhesion under most demanding conditions, such as the ones encountered in the gastrointestinal tract.

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Zoom: https://ethz.zoom.us/j/69333396880

Tuning polymer dispersity by photoinduced ATRP: monomodal distributions with ppm copper concentration

Richard Whitfield (Polymeric Materials – D-MATL)

Unlike natural biopolymers, such as DNA and proteins, synthetic polymers have a distribution of different molecular weight species. This distribution is measured by a dispersity value and has a significant influence on polymer properties. It is therefore highly beneficial to develop strategies to systematically tune the dispersity, however, current methods are limited to bimodal molecular weight distributions, adulterated polymer chains, or low end‐group fidelity and rely on feeding reagents, flow‐based, or multicomponent systems. To overcome these limitations, we have developed a simple batch system whereby photo-induced atom transfer radical polymerisation is exploited as a convenient and versatile technique to control the dispersity of both homopolymers and block copolymers. By varying the concentration of the copper complex, a wide range of monomodal molecular weight distributions can be obtained. In all cases, high end‐group fidelity was confirmed by MALDI‐ToF‐MS and exemplified by efficient block copolymer formation. Importantly, our approach utilises ppm levels of copper (as low as 4 ppm), can be tolerant to oxygen and exhibits perfect temporal control, representing a major step forward in tuning polymer dispersity for various applications.

Can 2-D Materials Save Moore’s Law?

Mathieu Luisier (Integrated Systems Laboratory – D-ITET)

Since the first experimental demonstration of a monolayer MoS 2 transistor in 2011, transition metal dichalcogenides (TMDs) have received a wide attention from the scientific community as potential replacement for Silicon FinFETs at the end of the semiconductor roadmap. As graphene, TMDs exhibit excellent electrostatic properties due to their 2-D nature, but contrary to it, they are characterized by large band gaps, while keeping decent mobilities. However, so far, no transistor based on a TMD channel could outperform the Si technology. While this limitation can be partly attributed to technical issues, the TMD bandstructure also explains this behavior: electrons/holes are not fast enough to allow for large ON-state currents. Through density functional theory (DFT), the existence of more than 1,800 2-D materials was recently predicted. Among them there might be components with better transport properties than TMDs. We therefore selected 100 monolayers out of this database, combined DFT and quantum transport to simulate their “current vs. voltage” characteristics, and identified 13 candidates with both n- and p-type ON-state currents larger than what Si FinFETs are expected to deliver in the future. In this talk, I will present the results of this study.

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Zoom: https://ethz.zoom.us/j/63151988666

From binary lipid-water phase diagrams to lipid nanoparticle-based mRNA
COVID-19 vaccines

Peter Walde (Laboratory for Multifunctional Materials – D-MATL)

The aim of the talk is to emphasize that basic research on the aggregation behavior of amphiphilic lipids in aqueous solution and on the controlled formation of lipid vesicles (liposomes) for drug delivery applications was essential for the successful development of lipid nanoparticle-based mRNA COVID-19 vaccines.

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Zoom: https://ethz.zoom.us/j/64504425191

Fuel cells, batteries, electrolyzers, etc.: some insights from a materials science point of view

Lorenz Gubler (Electrochemistry Laboratory – PSI)

Electrochemical storage & conversion technologies are expected to play a pivotal role in the energy transition and defossilization of our economy. In addition to batteries used for grid-scale energy storage and electromobility, electrochemical conversion devices using or producing hydrogen, i.e. fuel cells and electrolyzers, can contribute to reducing the carbon footprint of the transport sector and chemical industry. In this seminar, we will be looking at the state-of-the-art of these devices, and highlight selected challenges regarding the choice of cell materials and components. Examples from the research on these topics will be shown to illustrate current limitations of the technology and future prospects.

Do soft solids have strain-dependent surface tension?

Nicolas Bain (Soft and Living Materials – D-MATL)

Despite its importance in any adhesion and wetting phenomena, there is a fundamental property that is not yet understood in soft solids: surface elasticity. Also called the Shuttleworth effect, surface elasticity can be boiled down to one question. Does stretching the surface of a soft solid change its surface tension? In 2017, Xu et. al designed an experiment in which the opening angle of a wetting ridge was a proxy to evidence a dramatic increase of surface tension with stretch. In 2019, however, Masurel et al. claimed that the coupling between nonlinear mechanics and the singular nature of the wetting ridge suffice to explain the behavior of the opening angle observed by Xu et al, without invoking the Shuttleworth effect. The question, therefore, remains open. This presentation will focus on an experimental setup with no geometric singularity, that leaves no doubt on the existence or absence of surface elasticity in soft solids, hopefully closing this long-lasting controversy.

Q. Xu, K. E. Jensen, R. Boltyanskiy, R. Sarfati, R. W. Style, and E. R. Dufresne, Nature communications 8, 1 (2017).
R. Masurel, M. Roché, L. Limat, I. Ionescu, and J. Dervaux, Physical review letters 122, 248004 (2019).

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Zoom: https://ethz.zoom.us/j/66776813667

Interface stability in all-solid-state batteries

Corsin Battaglia (Materials for Energy Conversion – EMPA Dübendorf)

All-solid-state batteries combining an alkali metal anode and a high-voltage cathode have the potential to double the energy density of current-generation rechargeable batteries. However, interface stability remains a major challenge. On the anode side, alkali metal dendrites penetrating into the solid electrolyte limit the maximum plating current density and prevent fast charging, while on the cathode side the limited oxidative stability of solid electrolytes is a major challenge, especially when the battery is charged beyond 4V.
We recently discovered that the critical current density for dendrite formation in the archetypical ceramic solid electrolyte Na-β”-alumina can reach 10 mA/cm2 at room temperature, which is ten times higher than that measured on a garnet-type Li7La3Zr2O12 electrolyte [1]. Further, we demonstrated that above the melting temperature of sodium, a cumulative capacity of >10 Ah of sodium can be plated and stripped at an unprecedented current density of 1000 mA/cm2 without dendrite formation [2] indicating that the alkali metal and not the electrolyte prevent fast charging at room temperature.
We recently also demonstrated the integration of hydroborate electrolytes with a 4 V class cathode through in-situ formation of a passivating interface layer [3]. Combined with their high ionic conductivity >1 mS/cm at room temperature, low gravimetric density 1.2 g/cm3, low toxicity, high thermal and chemical stability, stability vs lithium and sodium metal, soft mechanical properties enabling cold pressing, compatibility with solution infiltration, and potential for low cost, hydroborate electrolytes represent a promising option for a competitive next-generation all-solid-state battery technology [4].
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[1] M.-C. Bay, M. Wang, R. Grissa, M. V. F. Heinz, J. Sakamoto, C. Battaglia, Adv. Energy Mater. 2019, 201902889
[2] D. Landmann, G. Graeber, M. V. F. Heinz, S. Haussener, C. Battaglia, Materials Today Energy 2020, 18,
[3] R. Asakura, D. Reber, L. Duchêne, A. Remhof, H. Hagemann, C. Battaglia, Energy Environ. Science 2020, 13, 5048
[4] L. Duchêne, A. Remhof, H. Hagemann, C. Battaglia, Energy Storage Mater. 2020, 25, 782

Sculpting hydrogels using advective processing

Alexandra Bayles (Soft Materials – D-MATL)

Polymeric hydrogels, water-laden 3D crosslinked networks, find broad application as advanced biomaterials and functional materials due to their biocompatibility, stimuli responsiveness, and affordability. In these materials, the crosslinking density reports material properties such as elasticity, strength, permeability, and swelling propensity. Patterning this critical design parameter across the volume polymerized is an attractive means by which to engineer hydrogel performance. In this talk, we present a novel processing scheme that uses laminar flow to direct the organization of hydrogel crosslinking density across a single sample. Inspired by techniques used to structure polymeric melts, we design custom millifluidic devices that force disparate streams through serpentine splitting, rotation, and recombination elements. These elements multiply the advecting macromer concentration distribution within the cross-sectional area while preserving its relative spacing and orientation. Incorporating advective assembly devices into conventional 3D printing nozzles enables the fabrication of hierarchical, shape-morphing hydrogels. This work exemplifies advective processing’s potential to encode soft material microstructure and subsequently functionality through geometrically dictated, generalizable flows.

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Zoom: https://ethz.zoom.us/j/65491333976

Open Access - funding opportunities and requirements within and outside ETH Zurich

Rainer Rees Mertins (ETH library – Open Access specialist)

The transformation in scholarly publishing is reflected in the increasing importance of open access, which is  becoming the new standard. The rapid growth of Open Access has been fueled by several factors. One of the most important being the requirements of science funders to make publicly funded research results available to the public. Nevertheless, many scientists also support open access publishing because they are skeptical towards the traditional publishers, the facilitated re-use of publications and the higher citation rates of open access publications. The talk will cover background information on open access and its advantages, but will mainly focus on the practical aspects and how ETH members can publish open access either via library funding or as green open access in the Research Collection. The open access requirements of the
most important funders as well as the institutional open access policy will also be covered.

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