System Bits: Jan. 19

Electromagnetic properties of graphene-boron nitride materials

Rice University and Montreal Polytechnic researchers reported that developing novel materials from the atoms up goes faster when some of the trial and error is eliminated. The work aims to simplify development of certain exotic materials for next-generation electronics.

Specifically, Rouzbeh Shahsavari, a Rice materials scientist, and Farzaneh Shayeganfar, a postdoctoral researcher at Montreal Polytechnic, designed computer simulations that combine graphene, the atom-thick form of carbon, with either carbon or boron nitride nanotubes.

The hope is that such hybrids can leverage the best aspects of their constituent materials. Defining the properties of various combinations would simplify development for manufacturers who want to use these exotic materials in next-generation electronics. The researchers found not only electronic but also magnetic properties that could be useful.

The calculated properties of a three-dimensional hybrid of graphene and boron nitride nanotubes would have pseudomagnetic properties, according to researchers at Rice University and Montreal Polytechnic. Click on the image for a larger version. (Source: Shahsavari Lab, Rice University)

Shahsavari’s lab studies materials to see how they can be made more efficient, functional and environmentally friendly including macroscale materials like cement and ceramics as well as nanoscale hybrids with unique properties. Whether it’s on the macroscale or microscale, if it is possible to know specifically what a hybrid will do before anyone goes to the trouble of fabricating it, cost and time can be saved, and new properties might be enabled that are not possible with any of the constituents.

Mapping entire buildings in 3D with mobile devices

In support of the vision-focused application arena, ETH Zurich researchers have developed a piece of software that makes it easy to create 3D models of entire buildings using a new type of tablet computer.

A 3D model of the ETH Zurich main building. The red line indicates the path the scientists took in order to generate it. The researchers optimized this image using additional offline calculations. (Source: ETH Zurich / Thomas Schöps)

When doctoral student Thomas Schöps wants to create a 3D model of the ETH Zurich main building, he pulls out his tablet computer. As he takes a leisurely walk around the structure, he keeps the device’s rear-facing camera pointing at the building’s façade. Bit by bit, a 3D model of the edifice appears on the screen. It takes him just 10 minutes to digitize a historical structure such as the main building.

He developed the software running on the device in cooperation with fellow researchers in a group led by Marc Pollefeys, Professor of Informatics. Development was carried out as part of Google’s Project Tango, in which the internet company is collaborating with 40 universities and companies. ETH Zurich is one of them.

The Project Tango developer tablet used by the scientists. (Source: ETH Zurich / Thomas Schöps)

The ETH scientists said their method works by purely optical means, and is based on comparing multiple images, which are taken on the tablet by a camera with a fisheye lens that uses the principle of triangulation in a manner similar to that applied in geodetic surveying. Simply put: the software analyzes two images of a building’s façade that were taken from different positions. For each piece of image information, each pixel in an image, it searches for the corresponding element in the other. From these two points and from the camera’s known position and viewing angle, the software can determine how far each picture element is from the device and can use this information to generate a 3D model of the object. Long gone are the days when the models were restricted to the outlines of buildings and basic features such as window openings and doorways. Instead, they now even show architectural details such as the arrangement of bricks in a stone façade.

The ETH scientists programmed the software for the latest version of the Project Tango mobile device, still in the development phase, but which have been available for purchase by interested software developers for a few months now, also in Switzerland.

The researchers stressed real-time feedback is possible because, thanks to its high processing power, all of the calculations are performed directly on the tablet. This also paves the way for applications in augmented reality, such as a city tour in which a tourist carries a tablet as they move around a city in real life. If they view a building ‘through’ their tablet, additional information about the building can be displayed instantly on the screen.

Other potential applications include the modeling of buildings, the 3D mapping of archaeological excavations, and virtual-reality computer games.
The technology could also be integrated into cars to allow them to automatically detect the edge of the road, for example, or the dimensions of a parking space especially for self-parking cars.

And in another type of mapping…

Sensors map brain signals

Chalmers University of Technology and University of Gothenburg researchers have developed sensors based on nanothreads that are superconducting in liquid nitrogen to allow new ways of measuring activity in the brain.

They expect the technique could revolutionize brain research and add to knowledge of how stress affects us, for example, along with simplifying diagnosis of patients suffering from neurological diseases.

Dag Winkler and Justin Schneiderman (Source: Chalmers University of Technology)

“This project is one of the most exciting things I have done in my research career,” Dag Winkler, Professor of Physics at Chalmers, said.

He and Justin Schneiderman, Associate Professor of Medical Technology at the University of Gothenburg and MedTech West, describe the interdisciplinary research project they are jointly coordinating that has the aim to develop a more sensitive sensor system for magnetoencephalography (MEG), an advanced instrument that measures brain activity.

They said the project brings researchers in physics, who are developing superconducting nanoscale components, together with brain researchers in neuroscience and physiology.

MEG uses a very expensive instrument that can record the magnetic fields produced by electric currents generated by neurons in the brain. Such systems are found at some specialist hospitals and are used both for research and clinical examinations, e.g., when preparing for surgical brain interventions, and in diagnosing epilepsy and dementia.

There is only one full MEG system in Sweden today. It was bought by Karolinska Institutet with funding from the Knut and Alice Wallenberg Foundation, and is operated by NatMEG – the Swedish National Facility for Magnetoencephalography– with which the project is collaborating.

By comparing the new sensor technology with this state-of-the-art MEG system while learning more about the clinical and research needs, the researchers said they will be able to further refine the components. They noted that the sensors that record the brain’s electrical activity inside the MEG use a highly sensitive detector called a SQUID – Superconducting Quantum Interference Device, and they have now developed a highly sensitive SQUID that will make MEG both less expensive and simpler to use. They hope they will be able to record brain activity with a higher resolution, like a camera with more pixels.

One major challenge in the project is to stitch together the technical research with its applications in the medical field. For instance, the technique will be used at the University of Gothenburg in studies on how the body is affected by stress. A further application will be to interpret the signals generated when we touch something – how the brain understands the difference between rough and smooth, for example.