Novel flexible terahertz camera can inspect objects with diverse shapes

 

The unique 2D THz camera patch can ease the restrictions pertaining to the shapes and locations of measurement samples. The proposed technology can potentially create a new research direction on all-around sheetsensors by incorporating THz, thermal, strain, and biochemical sensors through the self-aligned filtration process.

https://www.eurekalert.org/pub_releases/2021-02/tiot-nft021521.php

In today's digital age, the use of "Internet-of-things" (devices embedded with softwares and sensors) has become widespread. These devices include wireless equipment, autonomous machinery, wearable sensors, and security systems. With their intricate structures and properties stems the need to scrutinize them closely to assess their safety and utility and rule out any potential defects. But, at the same time, damage to the device during inspection must be avoided.

Terahertz (THz) imaging, based on radiation with frequencies between 0.1 and 10 THz, is one such non-destructive method that is rapidly gaining popularity owing to its high penetration, resolution, and sensitivity. Conventional THz cameras, however, are bulky and rigid, thereby limiting their potential in imaging uneven surfaces. Moreover, their high cost and lack of versatility in sensor configurations make them a rather impractical alternative, calling for more adaptable sensors.

To this end, a team of researchers from the Tokyo Tech, led by Associate Professor Yukio Kawano, have now addressed this gap by designing a flexible and free standing THz sensor array that can be used to image blind ends of irregularly shaped objects.

Ecstatic about their findings published in Advanced Functional Materials, Dr. Kawano states, "Given the diversity in shapes, structures, and sizes of test objects, the camera design and sensor must be adapted to conform to different configurations. In our study, we have developed a simple and cost-effective fabrication method for generating THz cameras with adaptable shapes."

The scientists knew that the material used in such sensors must have good absorption in the THz spectrum along with a high efficiency of converting emissions into detectable electric signals. For this reason, they selected carbon nanotube (CNT) films, which also possess good mechanical strength and flexibility. They passed the CNT solution through a polyimide film with laser induced slits and a membrane filter using a vacuum. Upon drying, the CNT solution remained as a free standing suspended structure between the layers of the patterned polyimide film. Further, they developed a simple fabrication process based on the self-assembly of CNT film array and its ability to from electrodes at both ends. For this, they evaporated metal electrodes over the patterned polyimide film. Together, these processes generated a THz camera patch sheet with multiple cameras. Interestingly, the structure of the suspended CNT film could be modified by altering the filtering conditions and thus the frictional force, making the process customizable.

Moreover, the patch sheet could be cut with scissors into smaller portable and wearable sensors that can be attached to the surface of the test object for better coverage. The researchers were able to demonstrate its industrial applications by detecting and visualizing cracks, impurities and uneven coating of polymers in a resin and by detecting sludge within a bent pipe, thus underscoring the potential of the camera in quality control operations.

Highlighting the applications of their design, Dr. Kawano remarks, "Our patch camera can be easily set up for imaging of large and unmovable objects. The unique 2D THz camera patch can ease restrictions pertaining to the shapes and locations of objects, contributing significantly to non-destructive monitoring sensor networks."

Abstract-A Perspective on Terahertz Next-Generation Wireless Communications

John F. O’Hara, Sabit Ekin, Wooyeol Choi, Ickhyun Song

https://www.mdpi.com/2227-7080/7/2/43

In the past year, fifth-generation (5G) wireless technology has seen dramatic growth, spurred on by the continuing demand for faster data communications with lower latency. At the same time, many researchers argue that 5G will be inadequate in a short time, given the explosive growth of machine connectivity, such as the Internet-of-Things (IoT). This has prompted many to question what comes after 5G. The obvious answer is sixth-generation (6G), however, the substance of 6G is still very much undefined, leaving much to the imagination in terms of real-world implementation. What is clear, however, is that the next generation will likely involve the use of terahertz frequency (0.1–10 THz) electromagnetic waves. Here, we review recent research in terahertz wireless communications and technology, focusing on three broad topic classes: the terahertz channel, terahertz devices, and space-based terahertz system considerations. In all of these, we describe the nature of the research, the specific challenges involved, and current research findings. We conclude by providing a brief perspective on the path forward. 

Abstract-5 G wireless telecommunications expansion: Public health and environmental implications

Cindy L. Russell 

https://www.sciencedirect.com/science/article/pii/S0013935118300161

The popularity, widespread use and increasing dependency on wireless technologies has spawned a telecommunications industrial revolution with increasing public exposure to broader and higher frequencies of the electromagnetic spectrum to transmit data through a variety of devices and infrastructure. On the horizon, a new generation of even shorter high frequency 5G wavelengths is being proposed to power the Internet of Things (IoT). The IoT promises us convenient and easy lifestyles with a massive 5G interconnected telecommunications network, however, the expansion of broadband with shorter wavelength radiofrequency radiation highlights the concern that health and safety issues remain unknown. Controversy continues with regards to harm from current 2G, 3G and 4G wireless technologies. 5G technologies are far less studied for human or environmental effects.

It is argued that the addition of this added high frequency 5G radiation to an already complex mix of lower frequencies, will contribute to a negative public health outcome both from both physical and mental health perspectives.

Radiofrequency radiation (RF) is increasingly being recognized as a new form of environmental pollution. Like other common toxic exposures, the effects of radiofrequency electromagnetic radiation (RF EMR) will be problematic if not impossible to sort out epidemiologically as there no longer remains an unexposed control group. This is especially important considering these effects are likely magnified by synergistic toxic exposures and other common health risk behaviors. Effects can also be non-linear. Because this is the first generation to have cradle-to-grave lifespan exposure to this level of man-made microwave (RF EMR) radiofrequencies, it will be years or decades before the true health consequences are known. Precaution in the roll out of this new technology is strongly indicated.

This article will review relevant electromagnetic frequencies, exposure standards and current scientific literature on the health implications of 2G, 3G, 4G exposure, including some of the available literature on 5G frequencies. The question of what constitutes a public health issue will be raised, as well as the need for a precautionary approach in advancing new wireless technologies.

What is the internet of things at nanoscale?

https://internetmedicine.com/2017/04/01/65348/

What is the internet of nanoscale things?

Nanoscale technology is enabling the development of devices as small as one to a few hundred nanometers (10^-9 meters). To give a sense of scale, a strand of human DNA is roughly 2.5 nanometers in diameter. At this scale, a nanomachine is defined as the most basic functional unit and able to perform simple tasks such as sensing or actuation.

The U.S.’ National Nanotechnology Initiative requested $1.5 billion in federal funding in fiscal year 2016 and has been awarded over $22 billion since FY 2001.

Coordination and information sharing among several nanomachines will expand the potential applications of individual devices both in terms of complexity and range of operation, according to the Georgia Institute of Technology. The resulting nano-networks will be able to cover larger areas, and reach hard-to-reach locations. Moreover, the interconnection of nanoscale devices with classical networks and the internet defines a new networking paradigm, to which Georgia Institute of Technology refers to as the “internet of nano-things.”

Use cases

Some potential applications include:

In-body networks monitoring real-time blood, sickness and breath tests;

Use in public locations to monitor the spread of viruses and diseases; and

Hooked up to wearable health and environmental trackers.

When it arrives, the internet of nanoscale things could provide much more detailed, inexpensive and up-to-date pictures of our cities, homes, factories – even our bodies. Today traffic lights, wearables or surveillance cameras are getting connected to the internet with  billions of expected nanosensors harvesting huge amounts of real-time information and beaming it up to the cloud, according to Scientific American.

Methods of communication

It is still not clear how nanomachines are going to communicate. Georgia Tech presents two main alternatives for communication in the nanoscale, namely molecular communication and nano-electromagnetic communication:

Molecular communication:

This is defined as the transmission and reception of information encoded in molecules. Molecular transceivers are expected to be easily integrated in nano-devices due to their size and domain of operation. These transceivers are able to react to specific molecules, and to release others as a response to an internal command or after performing some type of processing.

Nano-electromagnetic communication:

This is defined as the transmission and reception of electromagnetic radiation from components based on novel nanomaterials.

The unique properties observed in these materials will decide the specific bandwidth for emission of electromagnetic radiation, the time lag of the emission and the magnitude of the emitted power for a given input energy.

Network architecture for IoNT

Georgia Tech proposes the study of the terahertz band for nano-electromagnetic communication and provides a network architecture for nano devices.

In intrabody networks, nanomachines such as nanosensors and nanoactuators deployed inside the human body are remotely controlled from the macroscale and over the internet by an external user such as a health care provider. The nanoscale is the natural domain of molecules, proteins, DNA, organelles and the major components of cells. Amongst others, existing biological nanosensors and nanoactuators provide an interface between biological phenomena and electronic nano-devices, which can be exploited through this new networking paradigm.

In the interconnected office, every single element normally found in an office and even its internal components are provided of a nanotransceiver which allows them to be permanently connected to the internet.

The use cases in these different environments shows that nanotechnology has the ability to create new applications in the biomedical, industrial and military fields as well as in consumer and industrial goods.

Demands for nano IoT

These are factors, according to Georgia Tech, that will increase demand for nano devices:

Convenience and almost seamless deployment;

Tiny and nonobtrusive devices;

The possibility to harvest vibrational, mechanical or even electromagnetic energy from the environment;

Ultra-low power consumption; and

Reasonable computing capabilities.

Here are the physical components required for the internet of nano things architecture:

Nano-nodes

The smallest and simplest nanomachines, they are able to perform simple computation, have limited memory and can only transmit over very short distances, mainly because of their reduced energy and limited communication capabilities. Biological nanosensor nodes inside the human body and nanomachines with communication capabilities integrated in all types of things such as books, keys, or paper folders are good examples of nano-nodes.

Nano-routers

Comparatively larger computational resources than nano-nodes and are suitable for aggregating information coming from limited nanomachines. In addition, nano-routers also can control the behavior of nano-nodes by exchanging very simple control commands (on/off, sleep, read value, etc.). However, this increase in capabilities involves an increase in their size, and this makes their deployment more invasive. Nano-micro interface devices are able to aggregate the information coming from nanorouters, to convey it to the microscale, and vice versa.

Gateway

Enables the remote control of the entire system over the internet. For example, in an intrabody network scenario, an advanced cellphone can forward the information it receives from a nano-micro interface in our wrist to our health care provider. In the interconnected office, a modem-router can provided this functionality. Despite the interconnection of microscale devices, the development of gateways and the network management over the internet are still open research areas, in the remaining of this article we mainly focus on the communication challenges among nanomachines.

Technologies enabling smaller data collection

Scientists have started shrinking sensors from millimeters or microns in size to the nanometer scale, small enough to circulate within living bodies and to mix directly into construction materials. There are five new developments that are helping enable the shrinking of sensors and collection of data from nano devices, according to Computer Business Review.

Nanotubes

Carbon nanotubes are a nanotechnology constructed with a length-to-diameter ratio of up to 132,000,000:1.

Uses of the solution span from incorporation in portable electronics to help fighting cancer and creating artificial muscles.

Bleeding plastic

Scientists have also developed a bleeding plastic with self-healing capabilities that could put an end to nearly anything getting broken, including cars, airplanes or everyday devices.

Nano-nodes

Nano-nodes are nanomachines with the capability to perform simple computation, but could be used in the future to make nearly every object and person connected to the internet.

In a whitepaper from IEEE Wireless Communications, Ian Akyildiz and Josep Jornet from the Georgia Institute of Technology explained that nano-nodes have limited memory, and can only transmit over very short distances, mainly because of their reduced energy and limited communication capabilities.

Nanoantennas

Nanoantennas are a new emerging technology that could help power wearables, smarten up buildings or keep lights on.

How terahertz radiation could help brands identify consumers in future

We catch up one of the latest emerging technologies, terahertz radiation, and its future application in recognising individuals

http://www.cmo.com.au/article/607397/how-terahertz-radiation-could-help-brands-identify-consumers-future/

• BRAD HOWARTH 

Marketers have longed dreamed of being able to identify every one of their customers, regardless of how they are interacting.

It is a capability that digital technology has delivered in the online world, but as yet no method has proven effective for the vast majority of offline interactions. Facial and mobile device recognition have both yet to become sufficiently accurate to deliver a positive ID against a known identity in all situations.

But what if you could recognise a person by their own unique chemical signature?

It’s not a crazy as it sounds.

Data61 researcher, Ken Smart, has been investigating the uses of terahertz radiation for 15 years as a scanning and detection technology.

“It has the ability to penetrate opaque materials, such as packaging and things like that,” Smart says. “You can look for voids inside of materials, or you can look for corrosion under paint. And it has a high sensitivity to liquids, so you can tell the water content of the thing you are looking at.”

All of that makes terahertz scanners particularly adept at instantly detecting substances like pesticide on fruit. Smart says this is of huge value to the agricultural sector, where some traditional chemical tests might take up to 24 hours to deliver a result – an appalling delay for anyone wanting to sell perishable goods.

“If you can determine how much is there within minutes, you have an advantage,” Smart says.

The technology could also be used to detect counterfeit food, such as when expensive fish are substituted with cheaper ones in restaurants. It has also been used to scan beneath works of art to determine what might have been painted over, by identifying the individual pigments.

The terahertz radiation band sits between the millimetre radiation band, often used for full body scanners at airports, and the optical radiation band used by human eyes. It is a non-ionising form of radiation, meaning it is safer than some other scanning techniques, such as those that use x-rays.

That terahertz radiation is only now being considered for commercial applications is due to recent breakthroughs which have made it easier to create devices with the power profile needed to work with it.

“It’s easier now to make high power devices, so you get stronger penetration and it is easier to see different things,” Smart says. “As you go up in frequency the wavelength gets smaller so your resolution increases, and you can see finer detail that you can’t capture at lower frequencies.

“You get to see an almost-unique signature. The more refined a substance is, the more unique its signature is. But once you start combining substances it gets a little murkier to tease out which one is which.”

Smart says the power profile of terahertz scanners also make standoff testing difficult, with an effective range of ten metres.

“So when it gets beyond that you have atmospheric effects and all sorts of things working against you,” Smart says. “But as people work their way around some of these problems there can be solutions found.”

And while it can scan through cloth and paper, it can’t penetrate metallic objects.

Despite the possibilities, however, the murkiness and range issue mean it may be some time before shop owners are identifying visitors by their unique chemical signature.

“That’s in the future, quite a long way,” Smart says.

Abstract-Integrated millimeter-wave/terahertz sensor systems for near-field IoT

Payam Heydari

http://dl.acm.org/citation.cfm?id=2907985

The emergence of Internet of Things (IoT) has brought forth new opportunities by seamlessly integrating the physical world using computing, sensing, and wireless networks, transforming it into a cyber-physical system. An essential building block enabling an IoT is a sensing system. The use of "near-field communication (NFC)" has gained attention in recent years, as it enables low-power short-range sensing and wireless transfer of low content information. The NFC, however, is inapplicable in scenarios where the real-time high-resolution image or video of the object(s) needs to be sensed. The penetration of THz waves through many materials, which are impervious for visible light makes THz imaging akin to X-rays, except that THz radiation is non-ionizing and therefore not harmful to the object being imaged, especially living tissues. This special issue paper presents an overview of recent advances in the development of siliconbased mm-wave/THz imaging sensors for near-field IoT applications.

Making massive MIMOs for high speed short range comms

By:Graham Pitcher
http://www.newelectronics.co.uk/electronics-technology/making-massive-mimos-for-high-speed-short-range-comms/111039/

The communications issues related to the Internet of Things have been discussed over the last few years and a range of solutions is available, although some remain proprietary. But a new set of challenges is emerging as designers look to enable communications between devices taking advantage of nanotechnology.

In the words of Ian Akyildiz, professor of telecommunications at Georgia Tech in the US: “We’re now talking about the Internet of Nanothings.” And the research is being enabled by graphene.

“I first had the idea about nanoscale communications in about 2006,” he said, “but I thought the only way nanoscale machines could communicate would be through biology. But my PhD student Josep Jornet said we should look at electromagnetic means and we realised we could enable this in the THz band – and we found graphene.”

Transmitting at more than 1Tbit/s

Jornet started to explore how graphene could be used to create antennas and, between them, the team had success in its first year. “We validated performance, presented the concept at a conference and applied for a patent,” Prof Akyildiz noted.

What graphene enabled was an antenna that supported data rates in excess of 1Tbit/s, but only over distances of up to 1m. “That’s impractical for many applications,” he added.

Jornet, now an assistant professor at the State University of New York (SUNY), said that graphene has extraordinary properties when it comes to its use in antennas. “The most important thing is that it supports the propagation of surface plasmon polaritons and this is the key property that enables the development of small, efficient antennas.

“Plasmons – surface confined waves – exist in other materials,” he continued, “but generally at optical frequencies. This is the first time it has been achieved at the low end of the terahertz spectrum.”

“When electrons in graphene are excited by an incoming electromagnetic wave, they start moving back and forth,” Prof Akyildiz explained. “Because of graphene’s properties, this global oscillation of electrical charge results in a confined electromagnetic wave on top of the graphene layer.”

It would be possible to take advantage of plasmons in metals such as silver and gold, but this would mean devices operating at hundreds of THz. “While those frequencies might offer advantages in communication speed,” Prof Akyildiz, pointed out, “their range would be limited by propagation losses to just a few microns.” And copper is ruled out because it doesn’t support plasmons.

The nano antenna developed by the Georgia Tech team, working with researchers from SUNY, comprises a layer of graphene on a dielectric and a ground plane. “The graphene must be on top of a dielectric, such as gallium arsenide,” Prof Akyildiz said. “Metallic antennas don’t need this extra layer. It’s not like we have taken a classical design and used graphene; there’s a lot of IP involved in our antenna.”

While the team is working on single graphene antennas, their research holds out the prospect of something far more exciting – ultra massive MIMO antennas. Prof Akyildiz noted that the concept of MIMO antennas – many inputs, many outputs – emerged about 10 years ago.

“The first such devices were 2 x 2; now, it’s up to 64 x 64 and the approach is in the plans for 5G. But it has to be limited to small numbers – perhaps 100 x 100 – because you need a certain spacing between each antenna to avoid interference problems. But how much space is there in a small phone for a 100 x 100 MIMO?” he asked

Ultra massive MIMO antennas

Jornet added: “There has been much talk about massive MIMOs, but they are more likely to be used in basestations; we’re talking about using them in a mobile phone. When we work with graphene, we can make things smaller and put them closer together. We may be able to create a 1k x 1k MIMO and put it anywhere.”

Prof Akyildiz says 1024 graphene nano antennas can be created in an area of about 1mm2. “Plasmonic nano antenna arrays exhibit high gain, which can help us to increase the communication distance at THz frequencies,” he said. “For example, a 1k x 1k beamforming set up can provide a gain of about 80dB; enough to establish a 2Tbit/s link at 10m when transmitting at 1THz – more than two orders of magnitude better than any existing standard.”

Transmission distance, however, remains a challenge. “The atmosphere affects signal propagation at higher frequencies,” Jornet noted. “However, there are windows that allow longer distance transmission. We have ideas for distance aware modulation techniques and may be able to transmit over 50m, but we’re still looking for more.”

But the ultra massive MIMO array is, for the moment, a concept. “We have developed analytical and simulation models,” Prof Akyildiz continued. “Fabrication and experimental validation will follow in the near future.”

“Our project shows the concept of graphene based nano antennas is feasible, especially when taking into account very accurate models of electron transport in graphene,” he concluded. “Many challenges remain, but this is a first step toward creating advanced nanomachines with many applications in the biomedical, environmental, industrial and military fields.

“It may take another couple of years, but but they could change the entire communications paradigm because they’re so tiny.”

However, one other problem remains to be solved: the cost of graphene. Jornet said:“We can use small samples of graphene in the lab; enough to make an antenna and transceiver. We’re hoping the materials people can reduce the production cost so our antennas can be mass produced.”

Printable antennas may bring low cost and flexibility to a range of applications Researchers from the University of Manchester have used compressed graphene ink to print an RF antenna measuring 14cm x 3.5mm onto a piece of paper. According to the team, the antenna performed well enough to make it practical for use in RFID tags and wireless sensors. Graphene ink is usually made by mixing graphene flakes with a solvent, and sometimes a binder. Graphene ink with binders usually conducts electricity better, but only after the binder – an insulator – is broken down by annealing. But this high temperature process limits the surfaces onto which graphene ink can be printed. The team found that by printing and drying the ink, then compressing it with a roller, graphene’s conductivity was increased by more than 50 times. Researcher Dr Zhirun Hu said: “What makes printed graphene attractive for antenna applications is its ultra low cost and flexibility and the fact that it can be printed on any substrate without needing a high temperature process. We can use screen printing to produce graphene antennas, which suits low cost mass production.” Expanding, Dr Hu noted: “Being able to print antennas on any substrate means we could see a disruptive technology for low cost, wearable communications products. In addition, we’ll be able to print a complete RF transceiver in the near future.”

Tunable graphene antenna Europe funded Project Nano RF has demonstrated a graphene antenna that operates in the microwave spectrum and which can be tuned using an external voltage. The antenna is less than 1mm thick, with a diameter of 100mm, which makes it one of the smallest such devices. According to the researchers, the main application for the antenna will be in RF communications, where its tunability will allow switching of communication channels.

- See more at: http://www.newelectronics.co.uk/electronics-technology/making-massive-mimos-for-high-speed-short-range-comms/111039/#sthash.TxCeyxul.dpuf