System Bits: May 10

Topological insulators
In a finding that could open up a new pathway to advanced electronic devices and even robust quantum computer architecture, researchers from MIT; Oak Ridge, and Argonne National Laboratories; the Institute for Theoretical Physics in Bochum, Germany; the Institute for Theoretical Solid State Physics in Dresden; the Ecole Normale Superieure in Paris; and the Institute of Nuclear Physics, in Kolkata, India have discovered what they say is a new and unexpected magnetic effect.

The finding is based on a family of materials called topological insulators (TIs), the novel electronic properties of which might ultimately lead to new generations of electronic, spintronic, or quantum computing devices, the researchers said. The materials behave like ordinary insulators throughout their interiors, blocking electrons from flowing, but their outermost surfaces are nearly perfect conductors, allowing electrons to move freely. It is the confinement of electrons to this vanishingly thin surface that makes them behave in unique ways. 

Arrows indicate the spin direction in the ferromagnetic insulator (EuS, shown in red) and topological insulator (Bi2Se3, shown in blue) at the interface between the two materials.
(Source: MIT)

Harnessing the materials’ potential still faces numerous obstacles, including finding a way of combining a TI with a material that has controllable magnetic properties. And the researchers now say they have by bonding together several molecular layers of a topological insulator material called bismuth selenide (Bi2Se3) with an ultrathin layer of a magnetic material, europium sulfide (EuS). They said the resulting bilayer material retains all the exotic electronic properties of a TI and the full magnetization capabilities of the EuS.  

Interestingly, the researchers were surprised at the stability of that effect. They explained that while EuS itself is known to retain its ability to hold a magnetic state only at extremely low temperatures, just 17 degrees above absolute zero (17 Kelvin), the combined material keeps those characteristics all the way up to ordinary room temperature, which they expect could make all the difference for developing devices that are practical to operate. They think this could also open up new avenues of device design as well as research into a new area of basic physical phenomena. 

Robotic models in minutes
Purdue University researchers have created a computerized system for novice designers to convert static 3D objects into moving robotic versions made out of materials including cardboard, wood and sheet metal.  

The system is called CardBoardiZer, and evolved from previous work based in Karthik Ramani, the Donald W. Feddersen Professor of Mechanical Engineering at Purdue University’s C Design Lab. “We wanted to create a system that’s much easier to use than other design programs, which are too complicated for the average person to learn.”

This graphics depicts how a new system called CardBoardiZer allows novice designers to convert three-dimensional objects into moving robotic versions. (Source: Purdue University)

For example, he said, an object like a plastic dinosaur with immovable parts can be scanned using a laser scanner and then turned into a folding cardboard version with moveable head, mouth, limbs and tail.

“Once I have the rough shape, this system can take over from there,” Ramani said.

The models can then be motorized using a commercial product called Ziro, which grew out of work in the Purdue lab. Ziro uses motorized “joint modules” equipped with wireless communicators and micro-controllers. The user controls the robotic creations with hand gestures while wearing a wireless “smart glove.”

Electrical device tag-less id via electromagnetic emissions
Disney Research engineers recently detailed a radio frequency (RF) identification technology in order to improve asset management and inventory tracking.

For many applications, RFID tags are considered too expensive compared to the alternative of a printed bar code, which has hampered widespread adoption of RFID technology. To overcome this price barrier, they said, the work leverages the unique electromagnetic emissions generated by nearly all electronic and electromechanical devices as a means to individually identify them.

They explained that this tag-less method of radio frequency identification leverages previous work showing that it is possible to classify objects by type (i.e. phone vs. TV vs. kitchen appliance, etc), but a core question is whether or not the electromagnetic emissions from a given model of device, is sufficiently unique to robustly distinguish it from its peers.

The researchers said this is a low cost method for extracting the EM-ID from a device along with a new classification and ranking algorithm that is capable of identifying minute differences in the EM signatures. Their results show that devices as diverse as electronic toys, cellphones and laptops can all be individually identified with an accuracy between 72% and 100% depending on device type. And while not all electronics are unique enough for individual identifying, they have developed a probability estimation model that accurately predicts the performance of identifying a given device out of a population of both similar and dissimilar devices.

Ultimately, they believe EM-ID provides a zero cost method of uniquely identifying, potentially billions of electronic devices using their unique electromagnetic emissions.