Manufacturing Bits: Feb. 18

Polite robots help make cupcakes; avant-garde chips; insulator interconnects.


Polite cupcake helping robots

Cornell and Carnegie Mellon have made a new discovery about robots. If they sound less snippy when they communicate, listeners will respond better. In fact, developers of robots should develop systems that use less confrontational language.

In the study, entitled “How a Robot Should Give Advice,” researchers discovered that robots and humans are more likeable and less controlling when they used two types of words—hedges and discourse markers. Hedges are words like “maybe,” “probably” or “I think,” according to researchers. Discourse markers are syntax-independent words. They include the following words or phases: oh; well; now; then; you know; and I mean.

In an experiment, researchers videotaped people making cupcakes. The helpers in the experiment were robots and humans. The human helpers were actors working from scripts.

Then, the cupcake makers rated the helpers on scales of consideration, controlling and likability. Both humans and robots rated high when they used discourse markers, according to researchers. In fact, the robot actually rated higher, according to researchers.

“The robots need to seem human, so they may say things that don’t seem normal when a robot says them,” said Susan Fussell, associate professor of communication, on Cornell’s Web site.

A robot helper gives advice to a novice making cupcakes. (Source: Cornell)

A robot helper gives advice to a novice making cupcakes. (Source: Cornell)

Avant-garde chips

What’s the difference between futuristic chips and avant-garde art? As it turns out, very little, according to researchers from the Massachusetts Institute of Technology (MIT).

One technology–topological insulators–are generating interest in the market. These materials can conduct electrons even though their interiors are electrical insulators. In fact, MIT has discovered six new interacting electronic topological insulators. Combined with the previously known insulators, these produced a total of eight topologically distinct phases.

Two of the six interacting topological insulators can be described as Mott insulators. The remaining phases are obtained as combinations of these two “topological paramagnets.”

MIT physics professor Senthil Todadri said the topological insulators reminded him of the 1915 painting by Russian artist Kazimir Malevich, called “Black Circle.” (shown below). According to Wikipedia, Malevich was a pioneer of geometric abstract art and the originator of the avant-garde, Suprematist movement.

MIT researchers say the electrical behavior of topological insulators remind them of the 1915 painting by Russian artist Kazimir Malevich, called "Black Circle.” (Source: MIT)

MIT researchers say the electrical behavior of topological insulators remind them of the 1915 painting by Russian artist Kazimir Malevich, called “Black Circle.” (Source: MIT)

In the painting, the only interesting feature is the boundary between the black circle and the white background. in topological insulators, the electrical activity takes place just on the surface, not the interior.

“In contrast to conventional insulators, the surface of the topological insulators harbors exotic physics that are interesting both for fundamental physics, and possibly for applications,” Senthil said on MIT’s Web site.
“The surface of a three-dimensional material is two-dimensional,” Senthil said. “The kind of two-dimensional physics that emerges (on these surfaces) can never be in a two-dimensional material. There has to be something inside, otherwise this physics will never occur. That’s what’s exciting about these materials.”

Topological insulator interconnects

Three-dimensional (3D) topological insulators (TI) exhibit gapless topological insulating electronic phases on its surface and an insulating phase in its bulk. The National University of Singapore recently examined the feasibility of using a sub-10nm topological insulating material for the local electrical interconnects. The material used is called bismuth selenide (Bi2Se3).

Due to the suppression of backscattering, the material has been proposed as a future interconnect material to replace for copper for a thickness greater than 5nm. Bi2Se3 has a relatively large bulk bandgap (~ 0.3 eV) that provides greater isolation of the surface.

Researchers examined the electron mobility in 6 QL to 9 QL thick Bi2Se3 wires. Quantum transport was modeled over a range of temperature. “At room-temperature bulk Cu has mobility of ~ 30 cm2/V/sec and conductivity of 2.5-3.3 x 107 (Ω-m)-1,” according to researchers. “However in 3D-TI, to preserve topological protection from elastic scattering, the Fermi-level should be close to the Diracpoint. The DOS is considerably low around the Dirac-point compared to the large mode density in Cu at Fermi-level, and in fact vanishes to zero at the Dirac-point. The low DOS corresponds to bulk carrier density of ~ 1023 /m3 and conductivity even at low-temperature (~ 2K) lies in the range of 8.9-34.5 x 103 (Ω-m)-1.”

In other words, the technology has a long ways to go. “The results show that for the electrical interconnects there is a considerable degradation of mobility in Bi2Se3 wire, due to phonons at the room temperature, even though mobility is relatively robust to other defects,” according to researchers at the National University of Singapore. “Therefore, the trade-off to gain mobility by operating in topologically protected surface states, with inherently low Density of States (DOS), poses a challenge for 3D-TIs in interconnect application, at least at room temperature.”

  • Gary Dagastine

    Why aren’t they called topological conductors?