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ETH Zurich ­nveils the Future

By R. Colin Johnson

February 21, 2019

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At the Rethinking Design exposition during the World Economic Forum's Annual Meeting (Jan. 22–25), Switzerland's Eidgenössische Technische Hochschule Zürich (the Swiss Federal Institute of Technology in Zurich) brought the future, as far forward as 2050, to life.

ETH Zurich demonstrated some of the electronic, robotic, and material innovations that will carry us into the second half of the 21st century. Demonstrations included what ETH researchers called revolutionary electronics, motor-free submarines, and four-dimensional materials, all aimed at overcoming the spiraling energy budgets, materials hurdles, and resource scarcities facing global economies between now and 2050.

One of the most promising examples of next-generation electronics demonstrated was the multiferroics exhibit, in which ETH Zurich's Nicola Spaldin showed how he had combined the rare earth erbium with manganese to create erbium manganese oxide (ErMnO3), a multiferroic material featuring interdependent magnetic and electrical fields. That characteristic permits magnetic bits to be set and reset by electrical fields, using far less energy than setting and resetting bits with magnetic fields, as is common in today's devices.

Said Spaldin, "Multiferroics are certainly a candidate for further miniaturization of electronic devices, and perhaps more than the miniaturization, the driver is that they use a awful lot less energy that conventional electronics."

The magnetoelectric coupling of ErMnO3 and similar multiferroic materials will enable new energy-saving spintronic devices, tunnel magnetoresistance (TMR) sensors, and spin-valves that are tunable with an electric field. Since the magnetic spin orientations in a multiferroic thin-film can be electrically tuned, the magnetoresistance of a device can also be controlled by an electrical field. By 2050, ETH Zurich also predicts that multiple-state memory elements, which store data in both electric and the magnetic polarizations, will also be possible.

Together with ETH Zurich professor of multifunctional ferroic materials Manfred Fiebig, Spaldin has also shown that multiferroic crystals can also be used to perform miniaturized 'Big Bangs' for the first time. Fiebig and Spaldin have shown that topological defects in multiferroic crystals closely mimic the formation of "strings" during the Big Bang, a phenomenon previously been impossible to reproduce in the laboratory. According to the researchers, the spontaneous arrangement of the electric charges in multiferroic crystals follows the same rules that describe the universe during its early expansion after the Big Bang. As a result of their experiments, the initial fraction of a second after the Big Bang can now be studied in the lab.

A second exhibit displayed magnetic tunnel junctions, which can lower the power required by magnetic solid-state memory by using the spin-orbit torque of electrons. This technique does not save as much energy as the multiferroic solution, but beats flash, disks, and tape, plus has the advantage of already being proven on test chips, and should put in production by next year.

Traditional magnetic memory uses electrical current pumped through magnetic coils to generate a magnetic field that sets or resets magnetic bits. Over time, improved magnetoresistive materials have yielded improved disk and tape storage. Solid-state magnetic random access memories (MRAM) have been slow to develop into densities capable of competing with disks, tape, or even solid-state floating gate memories (flash).

Pursuing a different avenue, ETH Zurich researchers, along with colleagues at IMEC Leuven in Belgium, demonstrated a novel technique at the Rethinking Design exposition that adapts nanometer-thick multilayer metallic thin films to provide fast magnetic storage with exceedingly low energy consumption. It works by passing an electric current directly through a semiconductor wafer, which allows the magnetization in a tiny metal dot to be set and reset. Called spin-orbit torque, the effect accumulates electrons with opposite magnetic spins at the edges of a conductor; the electron spins, creating a magnetic field that causes the atoms in the magnetic storage layer to change orientation—flipping 0s to 1s and visa versa.

IMEC Leuven is working to commercialize the technique by optimizing the magnetic media for faster, lower-power operation while flipping bits on and off. So far, the researchers have fabricated prototype magnetic memory films on 300mm silicon wafers using conventional CMOS circuitry integrated with the magnetic medium using magnetic tunnel junctions. The resulting MRAMs have nanosecond-caliber read and write times, yet are nonvolatile, making them ideal for storing entire operating systems that are "instantly on," since they do not have to be loaded from disk or flash at startup.

A third exhibit illustrated the novel applications of four-dimensional (4D) design techniques, which add the dimension of time to traditional three-dimensional (3D) spatial printing. ETH Zurich researchers demonstrated flat-printed static structures that are easy to transport, but which deploy as 3D active systems differently in different media—in the water as motor-less 3D submarines, on land as 3D building scaffolds, and in space as 3D electricity generators.

ETH Zurich's Kristina Shea developed the print-flat/deploy-3D technique. At the Rethink Design exposition, she demonstrated how in water, her technique permits the exploitation of temperature fluctuations to propel the submarine without a motor, while her structures ship flat but deploy on land as 3D tetrahedron building skeletons; in space they launch as flat solar panels, but automatically unfold into 3D arrays in orbit.

Four-dimensional (4D) design techniques offer four advantages, according to Shea: they consume less raw material than standard structures; they require smaller volumes for shipping because they can be transported flat; they require no manual assembly, and they have no moving parts that can jam.

Shea's Engineering Design and Computing Lab (EDAC) at ETH Zurich is actively expanding on the 4D design idea with an increasing number of complex shapes that morph from small, flat inventories but which unfold as 3D spare parts.

The 4D concept harnesses potential energy designe into manufactuered objects, which is released during their deployment phase, such as temperature gradients inherent in sun-side/dark-side on land and in space, or in water currents for submersibles. As a result, there is no need for additional electronics, control circuits, batteries, motors, and special tools for deployment, according to ETH Zurich.

Shape-memory polymers can also be integrated into 4D designs, so 3D-printed objects can adapt to their environment and even propel themselves as a built-in capability.

Other products demonstrated at the Rethinking Design expo included soft, flexible robotic hands that can manipulate delicate objects, skater-bots with legs that end in small wheels, and smart dynamic casting robots that can extrude entire buildings with the help of mesh mould materials and spatial timber robots, along with smart slab flooring designs that can conserve concrete when the raw materials for it start running out circa 2050.

R. Colin Johnson is a Kyoto Prize Fellow who has worked as a technology journalist for two decades.

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