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RFID Chip

Researchers develop stickers similar to skin for monitoring health

Some health devices are on the edge of merging smoothly with our skin as wearable technology grows ever tinier and more sensitive. A flexible digital sticker has been developed by the Researchers at Stanford University that can track a person’s pulse, respiration and muscle activity simultaneously. The work appears in the Nature Electronics journal. 

Bodynet which is the explanation of the working of this novel device asserts that the delicate and lightweight sensors fuse easily with the skin, stretching and bending gradually with each motion, heartbeat or breath. These accurate wireless measurements are then transported from the sticker to a close-by flexible receiver which is cropped somewhere onto a person’s clothing. The device has only been experimented on one individual so far and the receiver of this device is still a bit clumsy and requires further development.

The researchers have planned to improve their model even after 3 years of work in the near future. They expect the device to be used for tracking sleep disorders and heart conditions in real-time by the physicians.

The chemical engineer Zhenan Bao said that they think that in the future they can develop a full-body skin-sensor array device that can assemble physiological information without intervening with a person’s normal behavior.

There is a long way to go, researchers are moving rapidly on wearable technologies. Recently, researchers worldwide have been building new methods to hold medical devices onto the skin or implant medical sensors in the tattoo ink. Recent reports on wearable devices predict that as the industry prospers, the market could rise from US$8.9 billion in 2018 to US$29.9 billion by 2023.

The new design from Stanford uses a magnificent new wireless system including an antenna made from metallic ink, screen-printed onto a rubber sticker that can bend and stretch like human skin, unlike the sensors that stick on the skin. The electric current flowing through this metallic ink is varied as it goes through the motions giving precise measurements of a person’s physicality. The very close contact motion with the skin in the flexible antennae can disturb the radio waves sent to the receiver.

The team of researchers had to develop a novel type of wireless communication based on radiofrequency identification (RFID) that would enable the antennae to transmit strong and reliable signals to the receiver without being stretched and contracted to fix this issue. The key-card generates an access code when placed near a receiver and then sends back to the receiver for access allowing for the battery-free key card to steal a little of the reader’s energy.

The authors concluded that in spite of the system with Bodynet stickers becoming insensitive to strain-induced antenna disruptions, it can still maintain full functionality even when subjected to 50 % strain. Moreover, they added that the device can potentially be used for real-time physiological and clinical findings in a modern personal health monitoring system by continuously analyzing critical human signals (pulse, respiration and body movement).

The researchers are planning to integrate sweat, temperature and other sensors into their sticker and also reducing the receiver’s size so it can one day be woven into clothing.

Journal Reference: Nature Electronics journal. 

MIT engineers build advanced microprocessor out of carbon nanotubes

MIT engineers build advanced microprocessor out of carbon nanotubes

After years of tackling numerous design and manufacturing challenges, MIT researchers have built a modern microprocessor from carbon nanotube transistors, which are widely seen as a faster, greener alternative to their traditional silicon counterparts.

The microprocessor, described today in the journal Nature, can be built using traditional silicon-chip fabrication processes, representing a major step toward making carbon nanotube microprocessors more practical.

Silicon transistors — critical microprocessor components that switch between 1 and 0 bits to carry out computations — have carried the computer industry for decades. As predicted by Moore’s Law, industry has been able to shrink down and cram more transistors onto chips every couple of years to help carry out increasingly complex computations. But experts now foresee a time when silicon transistors will stop shrinking, and become increasingly inefficient.

Making carbon nanotube field-effect transistors (CNFET) has become a major goal for building next-generation computers. Research indicates CNFETs have properties that promise around 10 times the energy efficiency and far greater speeds compared to silicon. But when fabricated at scale, the transistors often come with many defects that affect performance, so they remain impractical.

The MIT researchers have invented new techniques to dramatically limit defects and enable full functional control in fabricating CNFETs, using processes in traditional silicon chip foundries. They demonstrated a 16-bit microprocessor with more than 14,000 CNFETs that performs the same tasks as commercial microprocessors. The Nature paper describes the microprocessor design and includes more than 70 pages detailing the manufacturing methodology.

The microprocessor is based on the RISC-V open-source chip architecture that has a set of instructions that a microprocessor can execute. The researchers’ microprocessor was able to execute the full set of instructions accurately. It also executed a modified version of the classic “Hello, World!” program, printing out, “Hello, World! I am RV16XNano, made from CNTs.”

“This is by far the most advanced chip made from any emerging nanotechnology that is promising for high-performance and energy-efficient computing,” says co-author Max M. Shulaker, the Emanuel E Landsman Career Development Assistant Professor of Electrical Engineering and Computer Science (EECS) and a member of the Microsystems Technology Laboratories. “There are limits to silicon. If we want to continue to have gains in computing, carbon nanotubes represent one of the most promising ways to overcome those limits. [The paper] completely re-invents how we build chips with carbon nanotubes.”

Joining Shulaker on the paper are: first author and postdoc Gage Hills, graduate students Christian Lau, Andrew Wright, Mindy D. Bishop, Tathagata Srimani, Pritpal Kanhaiya, Rebecca Ho, and Aya Amer, all of EECS; Arvind, the Johnson Professor of Computer Science and Engineering and a researcher in the Computer Science and Artificial Intelligence Laboratory; Anantha Chandrakasan, the dean of the School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science; and Samuel Fuller, Yosi Stein, and Denis Murphy, all of Analog Devices.

Fighting the “bane” of CNFETs

The microprocessor builds on a previous iteration designed by Shulaker and other researchers six years ago that had only 178 CNFETs and ran on a single bit of data. Since then, Shulaker and his MIT colleagues have tackled three specific challenges in producing the devices: material defects, manufacturing defects, and functional issues. Hills did the bulk of the microprocessor design, while Lau handled most of the manufacturing.

For years, the defects intrinsic to carbon nanotubes have been a “bane of the field,” Shulaker says. Ideally, CNFETs need semiconducting properties to switch their conductivity on an off, corresponding to the bits 1 and 0. But unavoidably, a small portion of carbon nanotubes will be metallic, and will slow or stop the transistor from switching. To be robust to those failures, advanced circuits will need carbon nanotubes at around 99.999999 percent purity, which is virtually impossible to produce today.

The researchers came up with a technique called DREAM (an acronym for “designing resiliency against metallic CNTs”), which positions metallic CNFETs in a way that they won’t disrupt computing. In doing so, they relaxed that stringent purity requirement by around four orders of magnitude — or 10,000 times — meaning they only need carbon nanotubes at about 99.99 percent purity, which is currently possible.

Designing circuits basically requires a library of different logic gates attached to transistors that can be combined to, say, create adders and multipliers — like combining letters in the alphabet to create words. The researchers realized that the metallic carbon nanotubes impacted different pairings of these gates differently. A single metallic carbon nanotube in gate A, for instance, may break the connection between A and B. But several metallic carbon nanotubes in gates B may not impact any of its connections.

In chip design, there are many ways to implement code onto a circuit. The researchers ran simulations to find all the different gate combinations that would be robust and wouldn’t be robust to any metallic carbon nanotubes. They then customized a chip-design program to automatically learn the combinations least likely to be affected by metallic carbon nanotubes. When designing a new chip, the program will only utilize the robust combinations and ignore the vulnerable combinations.

“The ‘DREAM’ pun is very much intended, because it’s the dream solution,” Shulaker says. “This allows us to buy carbon nanotubes off the shelf, drop them onto a wafer, and just build our circuit like normal, without doing anything else special.”

Exfoliating and tuning

CNFET fabrication starts with depositing carbon nanotubes in a solution onto a wafer with predesigned transistor architectures. However, some carbon nanotubes inevitably stick randomly together to form big bundles — like strands of spaghetti formed into little balls — that form big particle contamination on the chip.

To cleanse that contamination, the researchers created RINSE (for “removal of incubated nanotubes through selective exfoliation”). The wafer gets pretreated with an agent that promotes carbon nanotube adhesion. Then, the wafer is coated with a certain polymer and dipped in a special solvent. That washes away the polymer, which only carries away the big bundles, while the single carbon nanotubes remain stuck to the wafer. The technique leads to about a 250-times reduction in particle density on the chip compared to similar methods.

Lastly, the researchers tackled common functional issues with CNFETs. Binary computing requires two types of transistors: “N” types, which turn on with a 1 bit and off with a 0 bit, and “P” types, which do the opposite. Traditionally, making the two types out of carbon nanotubes has been challenging, often yielding transistors that vary in performance. For this solution, the researchers developed a technique called MIXED (for “metal interface engineering crossed with electrostatic doping”), which precisely tunes transistors for function and optimization.

In this technique, they attach certain metals to each transistor — platinum or titanium — which allows them to fix that transistor as P or N. Then, they coat the CNFETs in an oxide compound through atomic-layer deposition, which allows them to tune the transistors’ characteristics for specific applications. Servers, for instance, often require transistors that act very fast but use up energy and power. Wearables and medical implants, on the other hand, may use slower, low-power transistors.

The main goal is to get the chips out into the real world. To that end, the researchers have now started implementing their manufacturing techniques into a silicon chip foundry through a program by Defense Advanced Research Projects Agency, which supported the research. Although no one can say when chips made entirely from carbon nanotubes will hit the shelves, Shulaker says it could be fewer than five years. “We think it’s no longer a question of if, but when,” he says.

After years of tackling numerous design and manufacturing challenges, MIT researchers have built a modern microprocessor from carbon nanotube transistors, which are widely seen as a faster, greener alternative to their traditional silicon counterparts.

The microprocessor, described today in the journal Nature, can be built using traditional silicon-chip fabrication processes, representing a major step toward making carbon nanotube microprocessors more practical.

Silicon transistors — critical microprocessor components that switch between 1 and 0 bits to carry out computations — have carried the computer industry for decades. As predicted by Moore’s Law, industry has been able to shrink down and cram more transistors onto chips every couple of years to help carry out increasingly complex computations. But experts now foresee a time when silicon transistors will stop shrinking, and become increasingly inefficient.

Making carbon nanotube field-effect transistors (CNFET) has become a major goal for building next-generation computers. Research indicates CNFETs have properties that promise around 10 times the energy efficiency and far greater speeds compared to silicon. But when fabricated at scale, the transistors often come with many defects that affect performance, so they remain impractical.

The MIT researchers have invented new techniques to dramatically limit defects and enable full functional control in fabricating CNFETs, using processes in traditional silicon chip foundries. They demonstrated a 16-bit microprocessor with more than 14,000 CNFETs that performs the same tasks as commercial microprocessors. The Nature paper describes the microprocessor design and includes more than 70 pages detailing the manufacturing methodology.

The microprocessor is based on the RISC-V open-source chip architecture that has a set of instructions that a microprocessor can execute. The researchers’ microprocessor was able to execute the full set of instructions accurately. It also executed a modified version of the classic “Hello, World!” program, printing out, “Hello, World! I am RV16XNano, made from CNTs.”

“This is by far the most advanced chip made from any emerging nanotechnology that is promising for high-performance and energy-efficient computing,” says co-author Max M. Shulaker, the Emanuel E Landsman Career Development Assistant Professor of Electrical Engineering and Computer Science (EECS) and a member of the Microsystems Technology Laboratories. “There are limits to silicon. If we want to continue to have gains in computing, carbon nanotubes represent one of the most promising ways to overcome those limits. [The paper] completely re-invents how we build chips with carbon nanotubes.”

Joining Shulaker on the paper are: first author and postdoc Gage Hills, graduate students Christian Lau, Andrew Wright, Mindy D. Bishop, Tathagata Srimani, Pritpal Kanhaiya, Rebecca Ho, and Aya Amer, all of EECS; Arvind, the Johnson Professor of Computer Science and Engineering and a researcher in the Computer Science and Artificial Intelligence Laboratory; Anantha Chandrakasan, the dean of the School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science; and Samuel Fuller, Yosi Stein, and Denis Murphy, all of Analog Devices.

Fighting the “bane” of CNFETs

The microprocessor builds on a previous iteration designed by Shulaker and other researchers six years ago that had only 178 CNFETs and ran on a single bit of data. Since then, Shulaker and his MIT colleagues have tackled three specific challenges in producing the devices: material defects, manufacturing defects, and functional issues. Hills did the bulk of the microprocessor design, while Lau handled most of the manufacturing.

For years, the defects intrinsic to carbon nanotubes have been a “bane of the field,” Shulaker says. Ideally, CNFETs need semiconducting properties to switch their conductivity on an off, corresponding to the bits 1 and 0. But unavoidably, a small portion of carbon nanotubes will be metallic, and will slow or stop the transistor from switching. To be robust to those failures, advanced circuits will need carbon nanotubes at around 99.999999 percent purity, which is virtually impossible to produce today.

The researchers came up with a technique called DREAM (an acronym for “designing resiliency against metallic CNTs”), which positions metallic CNFETs in a way that they won’t disrupt computing. In doing so, they relaxed that stringent purity requirement by around four orders of magnitude — or 10,000 times — meaning they only need carbon nanotubes at about 99.99 percent purity, which is currently possible.

Designing circuits basically requires a library of different logic gates attached to transistors that can be combined to, say, create adders and multipliers — like combining letters in the alphabet to create words. The researchers realized that the metallic carbon nanotubes impacted different pairings of these gates differently. A single metallic carbon nanotube in gate A, for instance, may break the connection between A and B. But several metallic carbon nanotubes in gates B may not impact any of its connections.

In chip design, there are many ways to implement code onto a circuit. The researchers ran simulations to find all the different gate combinations that would be robust and wouldn’t be robust to any metallic carbon nanotubes. They then customized a chip-design program to automatically learn the combinations least likely to be affected by metallic carbon nanotubes. When designing a new chip, the program will only utilize the robust combinations and ignore the vulnerable combinations.

“The ‘DREAM’ pun is very much intended, because it’s the dream solution,” Shulaker says. “This allows us to buy carbon nanotubes off the shelf, drop them onto a wafer, and just build our circuit like normal, without doing anything else special.”

Exfoliating and tuning

CNFET fabrication starts with depositing carbon nanotubes in a solution onto a wafer with predesigned transistor architectures. However, some carbon nanotubes inevitably stick randomly together to form big bundles — like strands of spaghetti formed into little balls — that form big particle contamination on the chip.

To cleanse that contamination, the researchers created RINSE (for “removal of incubated nanotubes through selective exfoliation”). The wafer gets pretreated with an agent that promotes carbon nanotube adhesion. Then, the wafer is coated with a certain polymer and dipped in a special solvent. That washes away the polymer, which only carries away the big bundles, while the single carbon nanotubes remain stuck to the wafer. The technique leads to about a 250-times reduction in particle density on the chip compared to similar methods.

Lastly, the researchers tackled common functional issues with CNFETs. Binary computing requires two types of transistors: “N” types, which turn on with a 1 bit and off with a 0 bit, and “P” types, which do the opposite. Traditionally, making the two types out of carbon nanotubes has been challenging, often yielding transistors that vary in performance. For this solution, the researchers developed a technique called MIXED (for “metal interface engineering crossed with electrostatic doping”), which precisely tunes transistors for function and optimization.

In this technique, they attach certain metals to each transistor — platinum or titanium — which allows them to fix that transistor as P or N. Then, they coat the CNFETs in an oxide compound through atomic-layer deposition, which allows them to tune the transistors’ characteristics for specific applications. Servers, for instance, often require transistors that act very fast but use up energy and power. Wearables and medical implants, on the other hand, may use slower, low-power transistors.

The main goal is to get the chips out into the real world. To that end, the researchers have now started implementing their manufacturing techniques into a silicon chip foundry through a program by Defense Advanced Research Projects Agency, which supported the research. Although no one can say when chips made entirely from carbon nanotubes will hit the shelves, Shulaker says it could be fewer than five years. “We think it’s no longer a question of if, but when,” he says.

Materials provided by Massachusetts Institute of Technology

Boeing X 37B

Spaceplane of US Air Force spends the longest time in orbit around Earth

The Boeing X-37B of US Air Force is a spaceplane which broke the record for the most amount of time in the orbit around Earth but it is unknown when the uncrewed plane is expected to land or what is it doing there because of the classified details about the X-37B mission.

The fifth mission of the X-37B, named the (OTV-5) Orbital Test Vehicle will have spent 719 days in the orbit, 11 days less than completing 2 years around the Earth. The previous record was for 717 days, 20 hours and 42 minutes which was achieved by OTV-4 a few years before.

The Air Force describes X-37B Orbital test Vehicle (OTV) as an experimental test program for demonstration of technologies which are suitable and reusable for the unmanned space platform for US Air Force. There are two main objectives of X-37B. The first is the reusable space technologies and the second consists of performing experiments that can be returned and examined back on Earth.

Upon receiving the commands, the OTV re-enters the atmosphere autonomously and lands on the runway. This is the first vehicle since the NASA Shuttle Orbiter to return back to Earth for inspection and analysis of the experiments however it can stay much longer in space, more than 270 days to be precise. Technologies which are currently tested are thermal protection systems, developed forms of guidance, reentry and landing, navigation and control, avionics, high-temperature structures and seals, reusable insulation, lightweight electromechanical flight systems, hi-tech propulsion systems, advanced materials and autonomous orbital flight.

It looks similar to space shuttles which were highly exciting during the 80s and 90s, but unfortunately, the space shuttle program has been abandoned, with the vehicles being placed in the museums.

The X-37B has completed 4 missions including the usage of Atlas 5 rocket however the most recent mission has been the launch of the SpaceX Falcon 9 rocket on September 7, 2017. Currently, no one knows what is going on in the experiments or what is the end goal and with things like a rise in fascism and disastrous Amazon fires and the way humans are destroying our own planet there is hope that the Air Force is developing some kind of human escape plan. Even the tardigrades have become a multiplanetary species so we can hope humans can achieve something similar. Every launch of the X-37B has taken place at Cape Canaveral in Florida, though some have landed at Vandenberg Air Force Base in California.

Researchers develop practical method for measuring quantum entanglement

Scientists come up with practical method for measurement of quantum entanglement

A team of scientists from Rochester Institute of Technology have created a new method for measuring the quantum entanglement (physical phenomenon that occurs when pairs or groups of particles are generated, interact, or share spatial proximity) that has significant consequences for building the future generation of technology in fields such as computer science, impersonation, safe communication and other areas. The new method for measuring entanglement(complexity) has been summarised by the scientists in a recently published article by Nature Communications journal.

An extraordinary interrelationship was observed in the measurements when two quantum particles like photons, electrons or atom become entangled even if the particles were apart from each other by a large distance. This special quality which can only be described by Quantum Mechanics is the backbone of the various technologies.

Gregory Howland, Assistant Professor and a member of Future Photon Initiative of Rochester Institute of Technology said that Quantum entanglement is a useful resource for performing important activities like quantum computing or secure communication. Also, he said that two people who possess entangled quantum particles can produce an unbreakable key to send messages back and forth to one another in such a way that in case if any third person or party intercepts the message, it will not be possible for them to decipher or decode the message according to laws of physics.

End-user needs to estimate the amount of quantum entanglement present within a given system as quantum technologies have become more sophisticated and complex with every passing day. The new method involving spatially entangled photon pairs needs million-times lesser measurements than the previous methods.

The measurement method has the additional advantage of never over-estimating the amount of entanglement which is present in a system as this method is based on the information theory which studies some of the key factors related to information such as quantification, storage and communication. It has been very crucial for milestone achievements such as compact disc invention, creation of the Internet, Voyager missions.

Howland said that this turns out to be vital because it is not that we are told that we have more of the resource then we actually have and this factor is mainly important for stuff like secure communication to avoid any unwanted interception of a message.

Journal Reference: Nature Communications journal

International Space Station after undocking of STS 132

The ISS Now Has Better Internet Than Most of Us After Its Latest Upgrade

  • Recently NASA upgraded the connection of ISS as a result of which it can transmit data at double the existing rate. ISS can now send and receive data at a speed of 600 megabit-per-second (Mbps)
  • For increasing the data rate, components in the global communications system were also upgraded
  • A new digital ground architecture for Space Network was upgraded along with circuits in the land data lines connecting various components on Earth. 
  • Data processors at NASA were changed along with the ISS software-based modem.

Data connectivity is very crucial in this age. We are constantly connected to each other through the web and it gets very important when it comes to research that can lead to deep space destinations such as the Moon and Mars. 

Recently NASA upgraded the connection of ISS as a result of which it can transmit data at double the existing rate. To ensure seamless transfer of mission data to control centres on Earth an effective communication system gets the top priority. ISS can now send and receive data at a speed of 600 megabit-per-second (Mbps)  at any point in time. Similar upgrades will be deployed in the Lunar Orbital Platform-Gateway proposed by NASA. 

George Morrow, acting centre director of Goddard Space Flight Center said that for every NASA mission, the communication system plays a very important role. It helps in the transfer of data from human spaceflight and space research missions to Earth. Upgradation in the communication transfer for ISS displays commitment in the services for current and future NASA missions. 

ISS has given the astronauts an opportunity to conduct research which would not be possible on Earth since its operations started in 2000. This has allowed learning about the effects of long duration in space on human bodies and testing of different technology in the presence of microgravity. All these experiments need very high speed of data transmission between ISS and Earth. Now it would be possible to conduct experiments which need higher resolution data. 

Risha George, upgrade project lead said that the project showed that advanced radiofrequency waveforms can be used for increasing the rate of data transmission and thereby improve the performance for high-speed communication services. They can also be used for missions in the future like the Gateway which will be a stepping stone to human exploration on Mars. Data communication between ISS and Earth takes place with the help of ground-based antennas known as Space Network and system of Tracking and Data Relay Satellites(TDRS).

These satellites are placed in a high orbit over various strategic locations so they can relay data to the ground, which is then sent to various NASA centres using landlines where it is interpreted. The entire process has a delay of less than a second. For increasing the data rate, components in the global communications system were also upgraded. A new digital ground architecture for Space Network was upgraded along with circuits in the land data lines connecting various components on Earth. 

Upgrades were also made to the ISS software-based modem, improved data-processors were installed at various NASA centres, as well as new software and hardware at the ground stations. Rigorous testing followed to check that the upgrades functioned properly. During the upgradation, the network still supported more than 40 missions in real-time. Penny Roberts, upgrade project lead for the space station said that it was possible due to cooperation from NASA which can take the partnership to scale new heights. 

industrial robot

Danish designers envision autonomous 3D printing robots for fixing the environment

Three Danish companies, GXN Innovation, the research wing of 3XN; Map Architects and The Danish AM Hub, the additive manufacturer have collaborated to form an initiative named Break the Grid. According to Break the Grid, coastlines and buildings could be maintained by autonomous 3D printers that have the ability to fix problems. It has proposed that by making 3D printers which can move and act independently problems such as damaged infrastructures and erosion of coastlines can be tackled. The 3D printers are visioned to have the power to move across all three forms of physical communication, land, sea and air.

Kasper Jensen, GXN founder said that it could be a revolution if 3D printers would be “freed” for tackling the challenges. If 3D printing robots are made to crawl, fly and swim then environmental threats can be handled at much lower costs with increased efficiency.

For tackling three separate cases, the companies have developed three different concept designs. In all the situations, the environment is scanned autonomously by the robots and the problems are then identified for the implementation of solutions.

In one of the designs, the robot can move underwater and construct artificial reefs. This can protect the coastlines from erosion and also provide habitat to aquatic creatures. It would function by extruding a mixture of sand from the ocean floor and glue which is inspired by a natural adhesive produced by oysters. In the meantime, a six-legged robot would scan the cities for micro-cracks and repair them. By detecting them early, the damage could be fixed before water further creeps in causing corrosion.

The land-based robots are visioned to 3D print a porous filler with a mixture of Trichoderma reesei, promoting the formation of calcium carbonate which creates a self-healing material. It can also patrol the infrastructure in urban areas remotely.

Another concept is drones operated in the air which can detect the damages in old buildings and then swoop in to repair the damages. It is based on the research that thermal insulation can be built using a customized composite of polymers and glass. The team has already been working on modifying the existing 3D printers for building the prototypes.

Mads Kjøller Damkjær, CEO of Danish AM Hub said that new approaches to construction can be built using converging technologies. New possibilities can be visualized only by the change of current ways of thinking which needs a combination of technology and design. Recent 3D printing developments have involved a plan for the 3D printed village and a stage for dance performances built by ETH Zurich students.

Pritzker School of Molecular Engineering research could lead to new technology

Scientists harness bacteria to create ‘living’ liquid crystals

Liquid crystals are widely used in technologies such as displays, which manipulate their orientation to display colors across the spectrum.

In traditional displays, liquid crystals are stationary and uniform, free of defects. But that stillness can be altered by adding bacteria to the crystals, creating what scientists and engineers call “living liquid crystals”: materials that can act autonomously. As bacteria swim around the liquid crystal, they generate “defects” that can be used for engineering purposes.

Juan de Pablo

Prof. Juan de Pablo

Researchers with the Pritzker School of Molecular Engineering at the University of Chicago, along with colleagues at UChicago-affiliated Argonne National Laboratory, have shown how this material becomes active and disordered through this process, creating floral patterns from the bending instabilities that eventually lead to creation of defects. But the results are not just aesthetic: They are an important step toward understanding how to ultimately control this material for emerging technologies that rely on defect formation.

“The genesis of these instabilities has been a topic of considerable debate, and now we truly understand how this process works, which will ultimately lead to controlling how this material behaves,” said Juan de Pablo, the Liew Family Professor in Molecular Engineering and co-author of the research, recently published in the journal Physical Review X.

Understanding pattern formation

Living liquid crystals are an example of materials that can act on their own. In nature, these materials are responsible for the motility of cells. Proteins within the cells “walk” along the surface of polymer molecules and exert a force that causes displacement and motion.

“There is a lot of interest in these materials because they are complex, beautiful and relevant,” said de Pablo, vice president for national laboratories. “But we want to understand just how motion and transport are generated within them.”

In the lab, one way to create an autonomous material like this is to combine a liquid crystal with bacteria, which then cause disorder among the liquid crystal when they move.

To study how the material becomes active, the researchers combined swimming bacteria with a liquid crystal in two formats: near the bottom surface of a drop suspended from a needle attached to a glass slide, and in a thin, freestanding film.

Though the bacteria and liquid crystal were initially aligned through a magnetic field, when the field was turned off, the bacteria began to move on their own, resulting in “bend instabilities.” These instabilities looked like petals on a flower or branches radiating out from a tree. The number of branches was controlled by the activity of the bacteria.

“Now we truly understand how this process works, which will ultimately lead to controlling how this material behaves.”

—Prof. Juan de Pablo

“The instabilities became more and more prominent as time proceeds, until the system eventually becomes completely disordered,” de Pablo said.

Through these experiments and computational simulations, the researchers discovered how these instabilities form through strain and geometry, and therefore developed a method to create and position the bend instabilities.

Controlling crystals for future technologies

The researchers hope to use this information to be able to fully control these living liquid crystals. That would allow them to eventually create a new kind of microfluidic device that transports fluids autonomously without pumps or pressure, or to create synthetic systems that resemble cells and that could move autonomously from one place to another.

“We have a real possibility to control these materials and use them for interesting new technologies,” de Pablo said.

Other authors include Alexey Snezhko, a physicist at Argonne; Andrey Sokolov, assistant scientist at Argonne; and postdoctoral researchers Ali Mozaffari and Rui Zhang.

Citation: Emergence of Radial Tree of Bend Stripes in Active Nematics. Sokolov et. al. Physical Review X, July 30, 2019. doi: 10.1103/PhysRevX.9.031014

Materials provided by the University of Chicago

quantum teleportation qubit

Researchers successfully achieve complex quantum teleportation for the first time

For the first time, researchers from Austria and China have managed to teleport three dimensional quantum states. This teleportation of higher dimensional states might play an important role in quantum computers in the coming days.

Scientists from the University of Vienna and the Austrian Academy of Sciences have demonstrated what was previously thought of as only a theoretical possibility. With the scientists from the University of Science and Technology of China, they were able to teleport complex high-dimensional quantum states. This is reported in the journal Physical Review Letters.

Scientists teleported the quantum state of a qutrit to another distant one. Earlier scientists were able to transport qubits, which have only two-level states. But scientists have now successfully teleported a qutrit which was created from the photon and has three-level states.

Since the 1990s, it was known that multidimensional quantum teleportation can be achieved. Manuel Erhard, Vienna Institute for Quantum Optics said that the first step was to design a technique to implement high-dimensional teleportation along with the technology. To teleport a quantum state, it is encoded in the possible paths which can be taken by the photon. Paths can be correlated to three optical fibers. Interestingly, in quantum physics, one photon might be present in all the fibres at once.

Bell measurement is at the core of quantum teleportation. A multiport beam splitter is used that directs photons with the help of many inputs and outputs thereby connecting the optical fibers. Also, auxiliary photons were used which were sent to the multiple beam splitter for interfering with other photons.

By selecting specific interference patterns, quantum information can be sent to a photon situated far away from input photon, without them interacting. This concept can be extended to as many dimensions as possible.

By achieving this, the research team has demonstrated that a quantum internet can be created in the future by transmitting large amounts of information. Anton Zeilinger, a scientist at Austrian Academy of Sciences and the University of Vienna said that the result will help in the connection of quantum computers having information capacities greater than qubits.

Chinese researchers also find immense potential in the field of multidimensional quantum teleportation. Jian-Wei Pan, University of Science and Technology of China said that their research will be the foundation for a quantum network system that can be built in the future. Pan presented his points at the University of Vienna and the Academy recently.

Quantum physicists in the future will also try to demonstrate the teleportation of the entire quantum state of one photon or atom.

Research Paper: Quantum Teleportation in High Dimensions

Colour-changing artificial ‘chameleon skin’ powered by nanomachines

Colour-changing artificial ‘chameleon skin’ powered by nanomachines

The material, developed by researchers from the University of Cambridge, is made of tiny particles of gold coated in a polymer shell, and then squeezed into microdroplets of water in oil. When exposed to heat or light, the particles stick together, changing the colour of the material. The results are reported in the journal Advanced Optical Materials.

In nature, animals such as chameleons and cuttlefish are able to change colour thanks to chromatophores: skin cells with contractile fibres that move pigments around. The pigments are spread out to show their colour, or squeezed together to make the cell clear.

The artificial chromatophores developed by the Cambridge researchers are built on the same principle, but instead of contractile fibres, their colour-changing abilities rely on light-powered nano-mechanisms, and the ‘cells’ are microscopic drops of water.

When the material is heated above 32C, the nanoparticles store large amounts of elastic energy in a fraction of a second, as the polymer coatings expel all the water and collapse. This has the effect of forcing the nanoparticles to bind together into tight clusters. When the material is cooled, the polymers take on water and expand, and the gold nanoparticles are strongly and quickly pushed apart, like a spring.

“Loading the nanoparticles into the microdroplets allows us to control the shape and size of the clusters, giving us dramatic colour changes,” said Dr Andrew Salmon from Cambridge’s Cavendish Laboratory, the study’s co-first author.

The geometry of the nanoparticles when they bind into clusters determines which colour they appear as: when the nanoparticles are spread apart they are red and when they cluster together they are dark blue. However, the droplets of water also compress the particle clusters, causing them to shadow each other and make the clustered state nearly transparent.

At the moment, the material developed by the Cambridge researchers is in a single layer, so is only able to change to a single colour. However, different nanoparticle materials and shapes could be used in extra layers to make a fully dynamic material, like real chameleon skin.

The researchers also observed that the artificial cells can ‘swim’ in simple ways, similar to the algae Volvox. Shining a light on one edge of the droplets causes the surface to peel towards the light, pushing it forward. Under stronger illumination, high pressure bubbles briefly form to push the droplets along a surface.

“This work is a big advance in using nanoscale technology to do biomimicry,” said co-author Sean Cormier. “We’re now working to replicate this on roll-to-roll films so that we can make metres of colour changing sheets. Using structured light we also plan to use the light-triggered swimming to ‘herd’ droplets. It will be really exciting to see what collective behaviours are generated.”

The research was funded by the European Research Council (ERC) and the Engineering and Physical Sciences Research Council (EPSRC).

Reference:
Andrew R Salmon et al. ‘Motile Artificial Chromatophores: Light-Triggered Nanoparticles for Microdroplet Locomotion and Color Change.’ Advanced Optical Materials (2019). DOI: 10.1002/adom.201900951

Materials provided by the University of Cambridge

A battery-free sensor for underwater exploration

A battery-free sensor for underwater exploration

To investigate the vastly unexplored oceans covering most our planet, researchers aim to build a submerged network of interconnected sensors that send data to the surface — an underwater “internet of things.” But how to supply constant power to scores of sensors designed to stay for long durations in the ocean’s deep?

MIT researchers have an answer: a battery-free underwater communication system that uses near-zero power to transmit sensor data. The system could be used to monitor sea temperatures to study climate change and track marine life over long periods — and even sample waters on distant planets. They are presenting the system at the SIGCOMM conference this week, in a paper that has won the conference’s “best paper” award.

The system makes use of two key phenomena. One, called the “piezoelectric effect,” occurs when vibrations in certain materials generate an electrical charge. The other is “backscatter,” a communication technique commonly used for RFID tags, that transmits data by reflecting modulated wireless signals off a tag and back to a reader.

In the researchers’ system, a transmitter sends acoustic waves through water toward a piezoelectric sensor that has stored data. When the wave hits the sensor, the material vibrates and stores the resulting electrical charge. Then the sensor uses the stored energy to reflect a wave back to a receiver — or it doesn’t reflect one at all. Alternating between reflection in that way corresponds to the bits in the transmitted data: For a reflected wave, the receiver decodes a 1; for no reflected wave, the receiver decodes a 0.

“Once you have a way to transmit 1s and 0s, you can send any information,” says co-author Fadel Adib, an assistant professor in the MIT Media Lab and the Department of Electrical Engineering and Computer Science and founding director of the Signal Kinetics Research Group. “Basically, we can communicate with underwater sensors based solely on the incoming sound signals whose energy we are harvesting.”

The researchers demonstrated their Piezo-Acoustic Backscatter System in an MIT pool, using it to collect water temperature and pressure measurements. The system was able to transmit 3 kilobytes per second of accurate data from two sensors simultaneously at a distance of 10 meters between sensor and receiver.

Applications go beyond our own planet. The system, Adib says, could be used to collect data in the recently discovered subsurface ocean on Saturn’s largest moon, Titan. In June, NASA announced the Dragonfly mission to send a rover in 2026 to explore the moon, sampling water reservoirs and other sites.

“How can you put a sensor under the water on Titan that lasts for long periods of time in a place that’s difficult to get energy?” says Adib, who co-wrote the paper with Media Lab researcher JunSu Jang. “Sensors that communicate without a battery open up possibilities for sensing in extreme environments.”


Preventing deformation

Inspiration for the system hit while Adib was watching “Blue Planet,” a nature documentary series exploring various aspects of sea life. Oceans cover about 72 percent of Earth’s surface. “It occurred to me how little we know of the ocean and how marine animals evolve and procreate,” he says. Internet-of-things (IoT) devices could aid that research, “but underwater you can’t use Wi-Fi or Bluetooth signals … and you don’t want to put batteries all over the ocean, because that raises issues with pollution.”

That led Adib to piezoelectric materials, which have been around and used in microphones and other devices for about 150 years. They produce a small voltage in response to vibrations. But that effect is also reversible: Applying voltage causes the material to deform. If placed underwater, that effect produces a pressure wave that travels through the water. They’re often used to detect sunken vessels, fish, and other underwater objects.

“That reversibility is what allows us to develop a very powerful underwater backscatter communication technology,” Adib says.

Communicating relies on preventing the piezoelectric resonator from naturally deforming in response to strain. At the heart of the system is a submerged node, a circuit board that houses a piezoelectric resonator, an energy-harvesting unit, and a microcontroller. Any type of sensor can be integrated into the node by programming the microcontroller. An acoustic projector (transmitter) and underwater listening device, called a hydrophone (receiver), are placed some distance away.

Say the sensor wants to send a 0 bit. When the transmitter sends its acoustic wave at the node, the piezoelectric resonator absorbs the wave and naturally deforms, and the energy harvester stores a little charge from the resulting vibrations. The receiver then sees no reflected signal and decodes a 0.

However, when the sensor wants to send a 1 bit, the nature changes. When the transmitter sends a wave, the microcontroller uses the stored charge to send a little voltage to the piezoelectric resonator. That voltage reorients the material’s structure in a way that stops it from deforming, and instead reflects the wave. Sensing a reflected wave, the receiver decodes a 1.

Long-term deep-sea sensing

The transmitter and receiver must have power but can be planted on ships or buoys, where batteries are easier to replace, or connected to outlets on land. One transmitter and one receiver can gather information from many sensors covering one area or many areas.

“When you’re tracking a marine animal, for instance, you want to track it over a long range and want to keep the sensor on them for a long period of time. You don’t want to worry about the battery running out,” Adib says. “Or, if you want to track temperature gradients in the ocean, you can get information from sensors covering a number of different places.”

Another interesting application is monitoring brine pools, large areas of brine that sit in pools in ocean basins, and are difficult to monitor long-term. They exist, for instance, on the Antarctic Shelf, where salt settles during the formation of sea ice, and could aid in studying melting ice and marine life interaction with the pools. “We could sense what’s happening down there, without needing to keep hauling sensors up when their batteries die,” Adib says.

Polly Huang, a professor of electrical engineering at Taiwan National University, praised the work for its technical novelty and potential impact on environmental science. “This is a cool idea,” Huang says. “It’s not news one uses piezoelectric crystals to harvest energy … [but is the] first time to see it being used as a radio at the same time [which] is unheard of to the sensor network/system research community. Also interesting and unique is the hardware design and fabrication. The circuit and the design of the encapsulation are both sound and interesting.”

While noting that the system still needs more experimentation, especially in sea water, Huang adds that “this might be the ultimate solution for researchers in marine biography, oceanography, or even meteorology — those in need of long-term, low-human-effort underwater sensing.”

Next, the researchers aim to demonstrate that the system can work at farther distances and communicate with more sensors simultaneously. They’re also hoping to test if the system can transmit sound and low-resolution images.