Combatting COVID-19 at the nano level

Today I bring to your attention a very recent report on the application of nanotechnology for the manufacture of masks against COVID-19. I want to share new interesting data with my readers, so I am giving a message completely without any changes. The message has a title “Combatting COVID-19 at the nano level”. It was published in the Nanowerk News.

Copper, a metal commonly used throughout history for its antibacterial properties, is being utilized by researchers at IUPUI’s Integrated Nanosystems Development Institute to solve a problem very relevant today: making reusable face masks safer and more comfortable for daily use.

“We wondered how we could use our existing technology to turn something used in ancient times, like copper, into protection against COVID-19,” said Mangilal Agarwal, director of the Integrated Nanosystems Development Institute and professor of mechanical and energy engineering. “Any virus sitting on the surface that comes in contact with copper will be killed because of the antiviral properties.”

Agarwal and Hamid Dalir, associate professor, are applying a patented technology developed at IUPUI to manufacture reusable face masks using copper, a metal often used in the production of high-touch objects like doorknobs and handles. Their goal is to improve filter performance by trapping and disabling airborne virus particles.

“These masks have copper oxide applied at the nano level and would offer ultimate protection against virus risks like COVID-19,” Agarwal said. “Some cloth masks allow the small airborne particles to pass through, but with our technology, it would be close to 100% proof that you have the capability incorporated in the mask to deactivate the virus and improve filter performance.”

The technology – initially developed at IUPUI to make composite materials cheaper, lighter and stronger using nanomaterials – could be used to coat household masks with a layer of fabric protection inlaid with copper nanoparticles that disable virus particles as they reach the surface. The general public would be able to wear a reusable mask that offers the same superior level of protection as masks worn by healthcare providers, such as N95 masks.

“To make any fabric into a mask or filter, we have to provide the nanostructure, and we can put that nanostructure on a roll-to-roll printing machine with the fibers at nanoscale,” Agarwal said. “We are using electrospinning, using the electric field to spray the nanofibers onto the fabric.”

Agarwal and Dalir disclosed their technology to the Indiana University Innovation and Commercialization Office, and are looking to commercialize it through their startup. They plan to work with local companies manufacturing COVID-19 supplies under the Defense Protection Act.

Beyond face masks, the technology can be applied to other methods for fighting COVID-19, such as HEPA filters found in HVAC systems. Without good filters, Agarwal said, airborne virus particles could circulate between indoor areas. By applying the copper material to the filters, there could be virus free air circulation in buildings and hospitals.

“Our technology is good for masks and filters because we are not changing the manufacturing process,” Dalir said. “We just get the rolls of the mask and filter, manufacture and enhance it with copper-coated fabric and then use it as it would be used conventionally.”

Their company, Multiscale Integrated Technology Solutions, was recently selected as one of five Hoosier startup winners of the Elevate Nexus Statewide Pitch Competition, a program designed to support Indiana startups.

“Elevate Nexus is being funded by a grant from the U.S. Economic Development Administration and the 21st Century Research and Technology Fund to help startups that have shown potential for commercialization to get connected with entrepreneurs to build on existing operational strategies," Dalir said. "What we're trying to do is raise the existing entrepreneurship support vehicles as well as attract investment in our startup at an earlier level so that we can have the opportunity to further grow and cultivate new investors as we de-risk our venture.”

The commercialization of their technology has the potential to greatly impact lives here in Indiana and around the world – providing a safe solution against the spread of COVID-19.

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Carbon nanotubes pave the way for human breath analysis of lung disease

 

Point-of-care health monitoring is still a challenging technology under development. Various sensors can be integrated into wearable devices for the monitoring of different health parameters like temperature and pulse rate. However to provide deep health analyses and a prediction for the existence of disease still requires the use of complicated diagnostic tools like MRI, computer tomography, etc, or body liquids analysis from blood, saliva, etc.

Breath is one of the main sources of human health parameters that can be used for predicting the state of different internal organs. Exhaled breath composition is very complex and the existence of disease marker molecules can be as low as 1 ppm (one part per million). That means that using breath for health monitoring purposes requires highly sensitive tools with a recognition ability down to single molecules.

Among a number of methods for breath analysis, the most promising one is based on the concept of an electronic nose. Here, the task for certain disease pattern recognition is moves from hardware to software using advanced methods of data analysis. This concept provides both miniaturizations of sensor designs and fast response times. Yet the development of sensor platforms that provide high sensitivity to the informative molecules with high humidity background in the exhaled breath is still challenging.

A team of researchers from Università Cattolica del Sacro Cuore (Italy), Skolkovo Institute of Science and Technology (Russia) and National Research University of Electronic Technology (Russia), has developed a method for fast, on-site and still accurate breath analysis that does not need special preparation of breath samples. The method is based on an electronic nose platform that uses a set of single-walled carbon nanotube (SWCNTs) sensors deposited on flexible substrates and modified by different semiconducting organic molecules. Carbon nanotubes are widely used for electronic nose development because of their high sensitivity to environmental gases, high stability, and intrinsic variations in electronic properties that make them perfect for use in electronic nose platforms. The researchers suggested improving the recognition properties of the SWCNT sensors by additional functionalization that increases the sensors' specificity to different gases, making sub-ppm analysis possible.

The researchers demonstrated the performance of this method by analyzing Various gases and vapors (ammonia, ethanol, acetone, 2-propanol, sodium hypochlorite, benzene, hydrogen sulfide, and nitrogen dioxide). The sensitivity was demonstrated down to 0.25 ppm for each nanotube sensor area of about 1 cm2 with high level of discrimination between gases. The best detection limit was demonstrated for ammonia for nanotubes covered by PANI molecules and hydrogen sulfide for CNT covered by TCTA molecules of 0.014 and 0.064 ppm, respectively.

Moreover, the team demonstrated that these sensors can be used for chronic obstructive pulmonary disease (COPD) recognition based on breath analyses of 21 individuals. Advanced data analysis methods based on principle component analyses provided a clear distinction between subjects with and without COPD.

The research team, led by Prof. L. Sangaletti, has demonstrated the high performance of their proposed sensing platform in-breath recognition with relatively fast response times without the need for complicated breath treatment. In the case of COPD, they observed that the analysis can be improved by properly targeting the molecules specific to the decease.

The main benefit of such an electronic nose platform is the possibility of future miniaturization and integration on a chip compatible with conventional microelectronics technologies, paving the way for on-site analysis using smartphones.

This project was funded in part by the ANAPNOI project (Catholic University of the Sacred Heart) and the Russian Science Foundation.

Nanowerk May 13, 2020

A Nanowerk exclusive provided by National Research University of Electronic Technology

 

 

 

 

 

 

 

 

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Nanowire device generates electricity from ambient humidity


Scientists in the US claim to have developed a device that can generate electricity from moisture in the air. The device, based around a thin film of electrically conductive protein nanowires, can produce continuous electrical power for around 20 hr, before self-recharging. The researchers say that such technology could provide clean energy without the restrictions on location and environmental conditions of other renewable energy solutions such as solar cells (Nature 10.1038/s41586-020-2010-9).

The device consists of a roughly 7 µm thin film of protein nanowires, harvested from the microorganism Geobacter sulfurreducens, deposited on a gold electrode with an area of around 25 mm2. A smaller, roughly 1 mm2, electrode is placed on top of the nanowire film.

Jun Yao, an electrical engineer at the University of Massachusetts, and his colleagues found that this set-up was able to produce a continuous current for more than 20 hr. After 20 hr, the voltage had dropped from around 0.5 V to 0.35 V, but when the load was removed, it went back up to 0.5 V within five hours, showing a self-recharging process.

The researchers also connected multiple devices together to increase the output. With 17 devices they were able to generate 10 V, and demonstrated that these connected devices could power an LED or a small liquid crystal display.

G. sulfurreducens was discovered by Derek Lovley, a microbiologist at the University of Massachusetts. He tells Physics World that the bacteria use the electrically conductive nanowires to make connections with other microbial species and with minerals. “For example, in soils and sediments, Geobacter ‘feeds’ electrons to methane-producing microorganisms, which use the electrons to convert carbon dioxide to methane,” Lovley says. “Geobacter also electrically connects to iron minerals in soils and sediments to use iron minerals similarly to how we use oxygen.”

Electricity from thin air

Energy is generated in the device due to a moisture gradient that forms within the nanowire film when it is exposed to the humidity naturally present in air, according to the researchers. The smaller electrode on the top is key, as it leaves one side exposed to the humid air, allowing the moisture gradient to develop.

Yao tells Physics World that the way the device works can be compared with lightning. “The cloud builds up positive and negative charges at the upper and lower sides, and upon a certain threshold, it discharges through the lightening,” he explains. “This indicates that charge can be build up from the ambient environment and we may be able to harvest it for electricity production. One can think of our device to be a small ‘cloud’, with one side open to air and the other sealed. Water molecules in the air constantly bump into the open surface, creating more charges than on the other one. The charge difference eventually will build up electric field or potential difference, which will drive the electric current output.”

The team experimentally determined that ambient humidity was the source of energy by sealing the top of the device, to block water-molecule exchange with the nanowires. This cut the electrical output, which returned once the seal was removed. They also found that increasing the ambient humidity, and thus the water-molecule exchange rate, increased the electric output. To check that there were no electrochemical reactions with the gold plates, the team replaced them with inert carbon electrodes, and were able to generate similar voltages. The device also worked in the dark, eliminating a photovoltaic effect.

Yao says that the researchers are now working on connecting devices together to increase the power volume. “We have demonstrated that the devices can be connected to increase the power, so at a certain point, it is proven this will scale,” he says. “We are working on material sciences and engineering strategies to scale up the technology.”

Physicsworld.com  March 03, 2020

Nature, vol.578, February 27, 2020

 

 

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New 3D Computer Chip Uses Nanotech to Boost Processing Power

Today's chips separate memory (which stores data) and logic circuits (which process data), and data is shuttled back and forth between these two components to carry out operations. But due to the limited number of connections between memory and logic circuits, this is becoming a major bottleneck, particularly because computers are expected to deal with ever-increasing amounts of data.

Previously, this limitation was masked by the effects of Moore's law, which says that the number of transistors that can fit on a chip doubles every two years, with an accompanying increase in performance. But as chip makers hit fundamental physical limits on how small transistors can get, this trend has slowed.

The new prototype chip, designed by engineers from Stanford University and the Massachusetts Institute of Technology, tackles both problems simultaneously by layering memory and logic circuits on top of each other, rather than side by side.

On top of this, the researchers used logic circuits constructed from carbon nanotube transistors, along with an emerging technology called resistive random-access memory (RRAM), both of which are much more energy-efficient than silicon technologies. This is important because the huge energy needed to run data centers constitutes another major challenge facing technology companies.

«To get the next 1,000-times improvement in computing performance in terms of energy efficiency, which is making things run at very low energy and at the same time making things run really fast, this is the architecture you need,» Mitra said.

While both of these new nanotechnologies have inherent advantages over conventional, silicon-based technology, they are also integral to the new chip's 3D architecture, the researchers said.

The reason today's chips are 2D is because fabricating silicon transistors onto a chip requires temperatures of more than 1,000 degrees Celsius, which makes it impossible to layer silicon circuits on top of each other without damaging the bottom layer, the researchers said.

But both carbon nanotube transistors and RRAM are fabricated at cooler than 200 degrees C, so they can easily be layered on top of silicon without damaging the underlying circuitry. This also makes the researchers' approach compatible with current chip-making technology, they said.

Stacking many layers on top of each other could potentially lead to overheating, Mitra said, because top layers will be far from the heat sinks at the base of the chip. But, he added, that problem should be relatively simple to engineer around, and the increased energy-efficiency of the new technology means less heat is generated in the first place.

To demonstrate the benefits of its design, the team built a prototype gas detector by adding another layer of carbon nanotube-based sensors on top of the chip. The vertical integration meant that each of these sensors was directly connected to an RRAM cell, dramatically increasing the rate at which data could be processed.

This data was then transferred to the logic layer, which was implementing a machine learning algorithm that enabled it to distinguish among the vapors of lemon juice, vodka and beer.

This was just a demonstration, though, Mitra said, and the chip is highly versatile and particularly well-suited to the kind of data-heavy, deep neural network approaches that underpin current artificial intelligence technology.

Jan Rabaey, a professor of electrical engineering and computer science at the University of California at Berkeley, who was not involved in the research, said he agrees.

«These structures may be particularly suited for alternative learning-based computational paradigms such as brain-inspired systems and deep neural nets, and the approach presented by the authors is definitely a great first step in that direction,» he told MIT News.

This  study was published online July 5, 2019  in the journal Nature.

Original article on Live Science.

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Nanotechnology in textiles

 

Nanoengineered functional textiles are going to revolutionize the clothing that we'll wear. The potential of nanotechnology in the development of new materials in the textile industry is considerable. It could make possible the manufacture of textiles with entirely new properties or the combination of different functions in one textile material.

The first generation of nano-enhanced textiles benefitted from nano finishing: coating the surface of textiles and clothing with nanoparticles is an approach to the production of highly active surfaces to have UV-blocking, antimicrobial, antistatic, flame retardant, water and oil repellent, wrinkle — resistant, and self-cleaning properties. One stubborn hurdle that prevents nanomaterial-enhanced textiles from becoming more of a commercial reality is the insufficient durability of nanocoatings on textile fibers or the stability of various properties endowed by nanoparticles. Quite simply put, the 'smart' comes off during washing.

While antimicrobial properties are exerted by nano-silver, UV blocking, self-cleaning and flame-retardant properties are imparted by nano-metal oxide coatings. Zinc oxide nanoparticles embedded in polymer matrices like soluble starch are a good example of functional nanostructures with potential for applications such as UV-protection ability in textiles and sunscreens, and antibacterial finishes in medical textiles and inner wears.

Published a review paper on  February 26, 2016, online edition of ACS Nano («Nanotechnology in Textiles») discusses electronic and photonic nanotechnologies that are integrated with textiles and shows their applications in displays, sensing, and drug release within the context of performance, durability, and connectivity.

In these smart clothes,  the textile structures themselves perform electronic or electric functions. Ideally, the nanoelectronic components will be completely fused with the textile material, resulting in that textile and non-textile components cannot be differentiated and 'foreign particles' can no longer be seen or felt.

Based on Nanowerk Spotlight, 2019

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Nanobolometer with ultralow noise equivalent power

 

Researchers from Aalto University and the VTT Finnish Technical Research Center have built an ultra-sensitive bolometer — a thermal radiation detector. Made from a gold-palladium mixture, it facilitates real-time measurement of electromagnetic radiation intensity.

An article about the development published in the journal Communications Physics.

A bolometer works by measuring the thermal effect of radiation. When this appliance heats up, its electrical characteristics change, and this can be fixed with high accuracy. The smaller the bolometer, the less radiation is required to heat it. A small radiation detector has a low heat capacity, so a low radiation intensity gives a stronger signal.

“Quantum computers operate in cryostats, extremely cold containers, where even the smallest amount of excess radiation causes great disturbance. Since nanobolometers are very sensitive, they can accurately measure the level of excess radiation in a cryostat to reduce radiation due to better protection, ”says one of the authors of the work, Mikko Mottenen, professor of quantum technology at Aalto University.

In the course of the work, physicists first built a radiation detector from gold, but it broke after a few weeks  because gold is incompatible with aluminum, which is used as a superconductor in the detector. To overcome this, the group began using an alloy of gold and palladium.

In the course of the study, scientists also developed microwave amplifiers. Their task is to amplify the signal, but they also amplify the noise. The superconducting microwave amplifier created by physicists was able to halve bolometric noise in comparison with the best commercial amplifier currently in use.

Roope Kokkoniemi et al,  Communication Physics 2, 124 (2019)

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Управляемые нанотрубки передвигают наночастицы

В работе американских ученых под руководством Джона Харта (John Hart) из Массачусетского технологического институт представлен новый способ управляемого перемещения микро- и наночастиц, основанный на эффекте электроадгезии  нанотрубок, то есть изменения силы сцепления нанотрубок и частиц в зависимости от приложенного электрического напряжения. Этот принцип позволяет работать как с металлическими, так и с диэлектрическими телам, а технологическое применение метода на его основе может привести к дальнейшей миниатюризации электроники, так как в данный момент этот процесс сдерживается, в том числе, сложностью уменьшения роботизированных захватов, пишут авторы в журнале Science Advances

Современные электронные устройства состоят из огромного количества крошечных элементов, которые с высокой точностью необходимо разместить в нужных местах на плате. Сегодня миниатюризация компонентов достигла масштаба крупинок муки. Например, самые современные светодиоды для дисплеев могут быть до нескольких микрон в размере.

Во многих случаях эти детали перемещаются специальными механическими или вакуумными захватами. Однако по мере сокращения размеров устройств данные способы удержания становятся все менее эффективными, так как в микромире гравитация убывает с уменьшением тел быстрее, чем поверхностные силы Ван-дер-Ваальса. В результате механические микроманипуляторы не справляются самостоятельно с размещением деталей на расчетных местах и нуждаются в дополнительном усилии, которым обычно является адгезия подложки.

В работе американских ученых под руководством Джона Харта (John Hart) из Массачусетского технологического института описан способ управления адгезией подложки, состоящей из неплотного леса покрытых диэлектрической керамикой углеродных нанотрубок. Созданное авторами на основе данного принципа устройство позволяет манипулировать объектами размером вплоть до 20 нанометров.

Приложение электрического напряжения временно поляризует диэлектрическую оболочку нанотрубок, что увеличивает адгезию, за которую в данном случае отвечает электростатика, более чем стократно. В результате лес нанотрубок, который в норме примерно в 40 раз менее «липкий», чем большинство других твердых тел, образует в разы более сильную связь при приложении 30 вольт. Соответствующая измеренная в эксперименте сила для площадки 200 на 200 микрон составила 2,3 микроньютона. Снятие напряжения вызывало резкое уменьшение адгезии. Продемонстрированный размер захватываемых частиц намного меньше возможностей современных механических манипуляторов, которые с трудом справляются с перемещением тел менее 50 микрон. Также ученые отмечают, что эффект электроадгезии уже используется в некоторых промышленных технологиях для перемещения крупных объектов, таких как ткани или кремниевые пластины. Однако этот принцип никогда ранее не применялся для микроскопических тел. Ранее этот же коллектив ученых продемонстрировал печать электронных схем с использованием нанотрубок. Также физики раскрыли «двуличность» углеродных нанотрубок и смогли их охладить постоянным током до квантового режима.

N + 1, S. Kim et al  Science Advances, 2019

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