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Seeing through walls helps locate firefighters in need of rescue



Firefighters Battle Fire

A unique positioning technology is being developed to detect firefighters inside buildings where other positioning technologies do not work.

When organizing rescue operations inside a building, firefighters are often faced with a rapidly changing environment, hidden by smoke and flames. Navigating a structure can be confusing, and if a firefighter gets lost or injured, a rescuer can quickly become the one to be rescued.

To reduce these dangers, NASAThe Jet Propulsion Laboratory and the Office of Science and Technology of the Department of Homeland Security (S&T) are developing POINTER (Precision Outdoor and Indoor Navigation and Tracking for Emergency Response), a system for detecting and tracking firefighters inside buildings when they risk their lives to save others. Short for Precision Outdoor and Indoor Navigation and Tracking for Emergency Response, the system began to take shape in 2014, and the technology is now being refined for use by fire departments across the country.

“Even with all the advances in fire suppression technology, we still lose too many firefighters every year,” said Greg Price, who leads S&T’s R&D programs. “We want them to know that we have their back, that we are working to give them the tools they need to ensure their own safety. POINTER is one of those rescue solutions. “

The Department of Science and Technology of the Ministry of Homeland Security has partnered with NASA’s Jet Propulsion Laboratory to develop POINTER, an innovative tracking technology for first responders that uses magnetokasi-static fields to 3D locate emergency responders, especially when visibility is low due to heavy smoke or debris. With POINTER, the incident team can identify team members to the nearest centimeter. Credit: Department of Homeland Security

Unlike positioning technologies such as GPS or RFID, POINTER does not use radio waves. Although radio waves are a reliable means of determining your position in relatively open areas, they can become unpredictable if you enter a room or find yourself surrounded by tall buildings. This can be a minor annoyance when trying to find a meeting point, but it can be a deadly situation when trying to find firefighters in a burning building.

Magnetoquasistatic fields

POINTER eliminates this unpredictability by using magnetically quasi-static (MQS) fields. A type of electromagnetic field, MQS fields have largely been ignored by researchers as a viable positioning tool due to their rapid decay with distance. But JPL Senior Research Technologist Darmindra Arumugam helped develop the mathematical and technological basis for their practical application, using lower frequencies to extend the range of this technology while providing highly accurate location data.

“These fields are not blocked or reflected by materials found in most buildings, as most building materials allow quasi-static magnetic fields to easily penetrate them,” said Arumugam, who is also POINTER’s principal investigator.

“This is a very exciting technology that adds another dimension to firefighters’ situational awareness.”
Ed Chow, POINTER Program Manager

MQS fields can occur when low frequency alternating electrical currents are passed through the coil. Electromagnetic fields have both electric and magnetic components, but at very low frequencies and for coil structures, the magnetic component in MQS fields becomes dominant. In a quasi-static range that can range from a few meters to thousands of meters (determined by the frequency passing through the coil), the MQS fields act much like a static magnetic field created by the interior of our planet. That is why this field is called “quasi-static”, which means nearly stationary or very slowly oscillating.

“This is significantly different from how wave-based remote positioning works,” added Arumugam. “While radio waves are blocked, reflected and attenuated by metal, cement and brick materials in buildings, magnetokasi-static fields are not. They run right through walls, creating a means of navigation and communication when line of sight is not available. “

This form of positioning technology will also have applications beyond Earth, Arumugam added. The MQS technique can be tuned over long distances, filling a significant technology gap for navigation sensors for some NASA space robot projects. Many of these robotic systems will need to navigate autonomously in challenging conditions out of line of sight and may require additional navigation capabilities. MQS fields can be used by robots penetrating ice, cave robots and underwater robotswhere traditional navigation methods don’t work.

Practical use

The POINTER system consists of three parts: a receiver, a transmitter and a base station. The firefighter carries a handset, which is currently the size of a mobile phone but is expected to be much smaller when redesigned. The transmitter, which can be attached to ambulances outside the building, generates MQS fields that pass through the building, interrogating any receivers located inside, at a distance of about 230 feet (70 meters) in the current version of the system.

This range can be expanded, but in most fire fighting applications it is not required. The receivers detect the fields, determine their three-dimensional location, and then send that data back outside the building to a laptop computer (base station). Visualization software shows where firefighters are in 3D space inside accuracy several inches.

POINTER can not only help fire brigades locate team members through walls, but MQS fields can also determine the orientation of the receiver. In other words, they can provide important information about whether the person providing first aid is standing or lying, moving or stationary, and in which direction he is looking.

POINTER receiver and transmitter

POINTER consists of receiver, transmitter and base station. Clockwise left: A prototype receiver is worn by firefighters and interacts with a transmitter coil that was attached to a failed fire engine for testing purposes. Credit: NASA / JPL-Caltech / DHS ST.

“This is a very interesting technology that adds another dimension to firefighters’ situational awareness,” said Ed Chow of JPL, POINTER program manager. “Firefighters can be tracked in real time, and if they stop responding, their team members can see if they are trapped in debris or injured so that a rescue operation can be organized.”

In a recent demo, POINTER was tested on an 8,000 square foot (750 square meters) three-level structure on the West Los Angeles Veterans Affairs Medical Center campus with an accuracy of less than one meter in 3D. throughout the structure. Multiple POINTER devices have been tested by the Department of Homeland Security’s Office of Science and Technology Office of Science and Technology First Response Resource Team and industry partner Balboa Geolocation Inc. to ensure they meet the first responder requirements.

The POINTER team is currently planning an online webcast of a technical demo at a two-level single-family home in Pasadena, California, near the California Institute of Technology campus, which manages jet propulsion for NASA. Further field trials in various firefighting scenarios are planned until 2021, and a commercial version of POINTER will be available to fire departments in 2022.

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Harvesting energy from radio waves to power wearable electronic devices



Flexible Self Powered Electronics

An international team of researchers led by Huanyu “Larry” Cheng, Dorothy Quiggle’s career development professor at the Pennsylvania Department of Engineering and Mechanics, has developed a stretchable antenna and rectenna system that harvests energy from radio waves in the environment to generate energy for wearable devices. Credit: Larry Cheng, PA.

Radio waves entering the environment, from microwaves to Wi-Fi connections, are not only signals of energy consumption, but are also energy sources themselves. An international team of researchers led by Huanyu “Larry” Cheng, Dorothy Quiggle’s career development professor at the Pennsylvania Department of Engineering and Mechanics, has developed a way to harvest radio wave energy to power wearable devices.

Researchers recently published their method in Materials Today Physics.

Current sources of energy for wearable health monitoring devices have their place in powering sensory devices, Cheng said, but each has its own drawbacks. For example, solar energy can only harvest energy when exposed to the sun. A self-powered triboelectric device can only collect energy when the body is in motion.

“We do not want to replace any of these current energy sources,” Cheng said. “We are trying to provide additional permanent energy.”

Researchers have developed a stretchable broadband dipole antenna system capable of wirelessly transmitting data from health monitoring sensors. The system consists of two expandable metal antennas embedded in the conductive graphene metal coated material. The system’s broadband design allows it to maintain its frequency functions even when stretched, bent and twisted. This system is then connected to a stretchable rectifier circuit, creating a rectified antenna, or “rectenna,” capable of converting electromagnetic wave energy into electricity. This electricity can be used to power wireless devices or to charge energy storage devices such as batteries and supercapacitors.

This rectenna can convert radio or electromagnetic waves from the environment into energy to power sensor modules on the device that pulse temperature, hydration, and oxygen levels. Compared to other sources, less power is generated, but the system can generate power continuously, which Cheng says is a significant advantage.

“We use the energy that already surrounds us – radio waves are everywhere and always,” Cheng said. “If we don’t use this environmental energy, it will be wasted. We can collect this energy and transform it into strength. “

Cheng said this technology is a building block for him and his team. Combining it with their new wireless communication device will provide a critical component that will work with existing command sensor modules.

“Our next steps will be to investigate miniature versions of these circuits and work to improve the extensibility of the rectifier,” Cheng said. “This is a platform on which we can easily combine and apply this technology with other modules that we have created in the past. It is easy to extend or adapt for other applications, and we plan to explore these possibilities. “

Link: Stretchable broadband dipole antennas and rectennas for collecting RF energy, by:
Jia Zhu, Zhihui Hu, Chaoyun Song, Ning Yi, Zhaozheng Yu, Zhendong Liu, Shangbin Liu, Mengjun Wang, Michael Gregory Dexheimer, Jian Yang and Huanyu Cheng, March 5, 2021, Materials Today Physics
DOI: 10.1016 / j.mtphys.2021.100377

This article was co-authored by Jia Zhu, who received his Ph.D. in Engineering and Mechanics from Pennsylvania State University in 2020; Zhihui Hu, former visiting professor of engineering and mechanics at the University of Pennsylvania and current associate professor at Wuhan University of Technology in China; Chaoyun Song, Assistant Professor in the Faculty of Engineering and Physical Sciences, Heriot-Watt University in Scotland; Ning Yi, who received her PhD in Engineering and Mechanics from Pennsylvania State University in 2020; Zhaozheng Yu, who received his MS in Engineering and Mechanics from Pennsylvania State University in 2019; Zhendong Liu, Former Visiting Graduate Student, Department of Engineering and Mechanics, University of Pennsylvania; Shangbin Liu, Graduate Student, Department of Engineering and Mechanics, University of Pennsylvania; Mengjun Wang, assistant professor at the School of Electronics and Computer Science, Hebei University of Technology in China; Michael Gregory Dexheimer, who received his MS in Engineering and Mechanics from Pennsylvania State University in 2020; and Jian Yang, professor of biomedical engineering in Pennsylvania.

Support for this work was provided by the National Science Foundation; National Heart, Lung, and Blood Institute, National Institutes of Health; and Penn State.

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Breakthrough in new materials could be the key to revolutionary transparent electronics



Flexible, Transparent Electronics


The optical transparency of the new materials can enable futuristic, flexible and transparent electronics. Credit: RMIT University.

Filling a critical gap in the material spectrum

A new study published this week could pave the way for the next generation of transparent electronics.

Such transparent devices could potentially be embedded in glass, flexible displays, and smart contact lenses to bring futuristic, sci-fi-like devices to life.

For several decades, researchers have been looking for a new class of electronics based on semiconductor oxides, the optical transparency of which could allow this fully transparent electronics to be used.

Oxide devices can also find applications in power electronics and communications technology, reducing the carbon footprint of our utilities.

A team led by RMIT has introduced ultrafine beta-tellurite in a family of two-dimensional (2D) semiconductor materials, providing an answer to this long-term search for a highly mobile p-type oxide.

“This new, highly mobile p-type oxide fills a critical gap in the material spectrum, enabling fast and transparent circuits,” says Team Leader Dr. Torben Daenecke, who led the collaborative work on the three FLEET nodes.

Other key advantages of long-sought oxide-based semiconductors are their stability in air, less stringent purity requirements, low cost, and ease of deposition.

“The missing link in our advance was finding the right, ‘positive’ approach,” says Torben.

Positivity was lacking

There are two types of semiconductor materials. “N-type” materials contain a large number of negatively charged electrons, while “p-type” semiconductors contain many positively charged holes.

It is the amalgamation of n-type and p-type complementary materials that allows electronic devices such as diodes, rectifiers, and logic circuits to be created.

Deposition of molten metal

The molten mixture of tellurium and selenium, rolled over the surface, precipitates an atomically thin sheet of beta-tellurite. Credit: FLEET

Modern life is critically dependent on these materials as they are the building blocks of every computer and smartphone.

An obstacle to oxide devices has been that although many high performance n-type oxides are known, there is a significant lack of high quality p-type oxides.

Theory prompts action

However, in 2018, a computational study found that beta tellurite (β-TeO2) could be an attractive candidate for p-type oxide, with tellurium’s special place on the periodic table means it can behave as a metal or non-metal, providing it oxide with unique beneficial properties.

“This prediction prompted our team at RMIT University to study its properties and applications,” says Dr. Torben Daenecke, FLEET associate researcher.

Liquid metal – the way to explore 2D materials

Dr. Daenecke’s team demonstrated the separation of beta-tellurite using a specially developed synthesis technology based on liquid metal chemistry.

“A molten mixture of tellurium (Te) and selenium (Se) is prepared and allowed to roll on the surface,” explains one of the authors of the article, Patjari Aukaraserinont.

“Due to the presence of oxygen in the ambient air, the melt drop naturally forms a thin surface oxide layer of beta-tellurite. When a drop of liquid rolls over the surface, this oxide layer sticks to it, depositing atomically thin sheets of oxide on its way. “

“The process is similar to drawing: you use a glass rod as a pen, and liquid metal is your ink,” explains Ms. Aucaraserenont, FLEET PhD student at RMIT.

Ali Zawabeti, Patjari Aukaraserinont and Torben Daeneke

RMIT Team (from left to right): Ali Zawabeti, Patjari Aukaraserinont and Torben Daeneke with transparent electronics. Credit: FLEET

While the desired β-phase of tellurite rises below 300 ° C, pure tellurium has a high melting point, above 500 ° C. Therefore, selenium was added to develop alloy which has a lower melting point, which makes synthesis possible.

“The ultra-thin sheets we got are only 1.5 nanometers thick, which equates to just a few atoms. The material was very transparent in the visible spectrum with a band gap of 3.7 eV, which means they are virtually invisible to the human eye, ”explains co-author Dr. Ali Zawabeti.

Beta Tellurite Evaluation: Up to 100X Faster

To evaluate the electronic properties of the developed materials, field effect transistors (FET) were manufactured.

“These devices showed characteristic p-type switching as well as high hole mobility (about 140 cm2V-1s-1), showing that beta-tellurite is ten to one hundred times faster than existing p-type oxide semiconductors. The excellent on / off ratio (over 106) also proves that this material is suitable for energy efficient and fast devices, ”said Ms. Patjari Aukaraserinont.

“The findings fill a major gap in the digital library of materials,” said Dr. Ali Zawabeti.

“Having a fast transparent p-type semiconductor at our disposal could revolutionize transparent electronics, as well as improve displays and improve energy efficient devices.”

The team plans to further explore the potential of this new semiconductor. “Our further research into this exciting material will focus on integration into existing and next generation consumer electronics,” says Dr. Torben Daenecke.

Link: “Highly mobile semiconductor two-dimensional β-TeO2 p-type” April 5, 2021, Nature Electronics
DOI: 10.1038 / s41928-021-00561-5

FLEET researchers from RMIT, ANU and UNSW collaborated with colleagues from Deakin University and the University of Melbourne. Matthias Wurdak of FLEET (ANU) conducted 2D nanosheets transfer experiments, and Kurosh Kalantarzade (UNSW) helped with material and device characteristics analysis.

This project was supported by the Australian Research Council (Center of Excellence and DECRA programs), the authors also acknowledge support from the RMIT University Microscopy and Microanalysis Foundation (RMMF), RMIT University Micronano-Nanotechnology Research Center (MNRF), and funding obtained through postdoctoral MacKenzie program. University of Melbourne Scholarship Program.

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Terahertz image of graphene paves the way for optimization and industrialization



Terahertz image of graphene paves the way for optimization and industrialization

Graphene Flagship researchers have developed a new measurement standard for the analysis of graphene and layered materials that can speed up production and optimize device fabrication. Credit: Graphene Flagship.

Graphene Flagship Researchers Develop a New Measurement Standard for Analysis graphene and multilayer materials that can speed up production and optimize device fabrication.

X-ray scans have revolutionized medical treatment by allowing us to see a person from the inside without surgery. Likewise, terahertz spectroscopy penetrates graphene films, allowing scientists to draw detailed maps of their electrical quality without damaging or contaminating the material. Graphene Flagship has brought together researchers from academia and industry to develop and refine this analytical method, and a new measurement tool is now ready to characterize graphene.

These efforts were made possible by a collaborative environment created by the European consortium Graphene Flagship, with the participation of scientists from Graphene Flagship partners, DTU, Denmark, IIT, Italy, Aalto University, Finland, AIXTRON, UK, imec, Belgium, Graphenea, Spain, University of Warsaw, Poland, and Thales R&T, France, as well as employees in China, Korea and the USA.

Graphene is often sandwiched between many different layers and materials used in electronic and photonic devices. This complicates the quality assessment process. Terahertz spectroscopy simplifies the task. It displays encapsulated materials and shows the quality of the graphene underneath, exposing flaws at critical points in the manufacturing process. It is a fast, non-destructive technology that explores the electrical properties of graphene and laminates without the need for direct contact.

The development of characterization techniques such as terahertz spectroscopy is fundamental to accelerating large-scale production as they ensure that graphene devices are produced consistently and predictably, without drawbacks. Quality control precedes trust. With other developments pioneered by Graphene Flagship, such as roll-to-roll graphene and laminates, fabrication technology is poised to take the next step. Terahertz spectroscopy allows us to ramp up graphene production without losing quality.

Terahertz image of graphene opens the way to industrialization

Terahertz spectroscopy penetrates graphene films, allowing scientists to draw detailed maps of their electrical quality without damaging or contaminating the material. Credit: Peter Baggild (Graphene Flagship / DTU)

“This is the method we need to meet the high performance production levels provided by Graphene Flagship,” explains Peter Baggild of DTU, Graphene Flagship partner. “We are confident that terahertz spectroscopy in graphene production will become as routine an X-ray scan in hospitals,” he adds. “In fact, thanks to terahertz spectroscopy, you can easily map even meter-scale samples of graphene without touching them, which is not possible with some other modern methods.” In addition, Graphene Flagship is currently exploring how to apply terahertz spectroscopy directly to graphene roll-to-roll production lines and accelerate imaging.

Collaboration was key to this achievement. Graphene Flagship researchers in academia have worked closely with leading graphene manufacturers such as Graphene Flagship partners AIXTRON, Graphenea, and IMEC. “This is the best way to ensure that our solution is relevant to our end users, companies that produce graphene and laminates on an industrial scale,” says Böggild. “Our publication is a comprehensive case study that highlights the versatility and reliability of terahertz spectroscopy for quality control and should help our colleagues apply this technique to many industrially important substrates such as silicon, sapphire, silicon carbide and polymers.” he adds.

Setting standards is an important step in the development of any new material to ensure that it is safe, authentic, and offers reliable and consistent performance. This is why Graphene Flagship has a dedicated working group dedicated to graphene standardization, measurement and analytical methods, and manufacturing processes. The newly developed terahertz spectroscopy method will soon become a standard technical specification thanks to the work of the Flagship Committee on Graphene Standardization. “This will undoubtedly accelerate the adoption of this new technology as it will show how the analysis and comparison of graphene samples can be performed in a reproducible manner,” explains Peter Jepsen of Graphene Flagship Partner DTU, co-author of the study. “Terahertz spectroscopy is another step towards increasing confidence in products containing graphene,” he concludes.

Amaya Zurutuza, article co-author and scientific director of Graphene Flagship, a Graphenea partner, says: “At Graphenea, we are convinced that terahertz imaging can help develop quality control methods that can meet manufacturing requirements and provide relevant information on graphene quality. what is needed on our way to the successful industrialization of graphene. “

Turid Gspann, Chair of the Flagship Graphene Standardization Committee, says: “This terahertz [spectroscopy] It is expected that this technology will become widespread in industry. It does not require any special sample preparation and is a mapping method that allows you to analyze large areas with a minimum of time. “

Marco Romagnoli, Head of Electronics and Photonics Integration, Graphene Flagship, adds: “The THz Spectroscopy Instrument for wafer scale applications is a state of the art high TRL system for characterizing multilayer stacks on wafers containing CVD graphene. Works in a short time and with good accuracy, and provides the main parameters of interest such as carrier mobility, conductivity, scattering time, and carrier density. This valuable technical achievement also exemplifies the benefits of being part of a large collaborative project such as the Graphene Flagship. “

Andrea C. Ferrari, Graphene Flagship Science and Technology Officer and Chair of its Management Group, adds: “Once again, Graphene Flagship researchers are pioneering new characterization techniques to drive the development of graphene technology. This helps us move steadily along our innovation and technology roadmap and will drive the commercialization of graphene in a wide range of applications. ”

Reference: “Case Studies of the Electrical Characteristics of Graphene Using Terahertz Time Domain Spectroscopy” by Patrick R. Welan, Bingbin Zhou, Odile Bezensnet, Abhaya Shivayogimatha, Niraja Mishra, Qian Shen, Bjarke S. Jessen, Iwona Pasternak, David MA Mackenzie, G.G. , Kunzhi Sun, Pierre Seneor, Bruno Dlubak, Birong Luo, Frederic Vosterberg, Depin Huang, Haofei Shi, Da Luo, Meihui Wang, Rodney Su Ruoff, Ben R. Conran, Clifford McAlees, Cedric Huygebaert, Stephen Brems, Ilarothy J. Attack, Wlodek Strupinski, Dirch H. Petersen, Stephen Forti, Camilla Coletti, Alexander Juvre, Kenneth B.K. Theo, Alba Centeno, Amaya Zurutuza, Pierre Leganier, Peter U Jepsen and Peter Baggild, February 17, 2021, 2D materials
DOI: 10.1088 / 2053-1583 / abdbcb

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