TriboElectricity, The Green Energy Source

Researchers from Clemson’s Nanomaterials Institute (CNI) are one step closer to wirelessly powering the world using triboelectricity, a green energy source. In March 2017, a group of physicists at CNI invented the ultra-simple triboelectric nanogenerator or U-TENG, a small device made of plastic and tape that generates electricity from motion and vibrations. When the two materials are brought together — through such actions as clapping the hands or tapping feet — they generate voltage that is detected by a wired, external circuit. Electrical energy, by way of the circuit, is then stored in a capacitor or a battery until it’s needed.

Nine months later, in a paper published in the journal Advanced Energy Materials, the researchers reported that they had created a wireless TENG, called the W-TENG, which greatly expands the applications of the technology. The W-TENG was engineered under the same premise as the U-TENG using materials that are so opposite in their affinity for electrons that they generate a voltage when brought in contact with each other.

In the W-TENG, plastic was swapped for a multipart fiber made of graphene — a single layer of graphite, or pencil lead — and a biodegradable polymer known as polylactic acid (PLA). PLA on its own is great for separating positive and negative charges, but not so great at conducting electricity, which is why the researchers paired it with graphene. Kapton tape, the electron-grabbing material of the U-TENG, was replaced with Teflon, a compound known for coating nonstick cooking pans.

After assembling the graphene-PLA fiber, the researchers pulled it into a 3-D printer and the W-TENG was born. The end result is a device that generates a maximum of 3,000 volts — enough to power 25 standard electrical outlets or, on a grander scale, smart-tinted windows or a liquid crystal display (LCD) monitor. Because the voltage is so high, the W-TENG generates an electric field around itself that can be sensed wirelessly. Its electrical energy, too, can be stored wirelessly in capacitors and batteries.

It cannot only give you energy, but you can use the electric field also as an actuated remote. For example, you can tap the W-TENG and use its electric field as a ‘button’ to open your garage door, or you could activate a security system — all without a battery, passively and wirelessly,” said Sai Sunil Mallineni, the first author of the study and a Ph.D. student in physics and astronomy.


How To Draw Electricity from the Bloodstream

Men build dams and huge turbines to turn the energy of waterfalls and tides into electricity. To produce hydropower on a much smaller scale, Chinese scientists have now developed a lightweight power generator based on carbon nanotube fibers suitable to convert even the energy of flowing blood in blood vessels into electricity.

For thousands of years, people have used the energy of flowing or falling water for their purposes, first to power mechanical engines such as watermills, then to generate electricity by exploiting height differences in the landscape or sea tides. Using naturally flowing water as a sustainable power source has the advantage that there are (almost) no dependencies on weather or daylight. Even flexible, minute power generators that make use of the flow of biological fluids are conceivable. How such a system could work is explained by a research team from Fudan University in Shanghai, China. Huisheng Peng and his co-workers have developed a fiber with a thickness of less than a millimeter that generates electrical power when surrounded by flowing saline solution—in a thin tube or even in a blood vessel.

The construction principle of the fiber is quite simple. An ordered array of carbon nanotubes was continuously wrapped around a polymeric core. Carbon nanotubes are well known to be electroactive and mechanically stable; they can be spun and aligned in sheets. In the as-prepared electroactive threads, the carbon nanotube sheets coated the fiber core with a thickness of less than half a micron. For power generation, the thread or “fiber-shaped fluidic nanogenerator” (FFNG), as the authors call it, was connected to electrodes and immersed into flowing water or simply repeatedly dipped into a saline solution. “The electricity was derived from the relative movement between the FFNG and the solution,” the scientists explained. According to the theory, an electrical double layer is created around the fiber, and then the flowing solution distorts the symmetrical charge distribution, generating an electricity gradient along the long axis.

The power output efficiency of this system was high. Compared with other types of miniature energy-harvesting devices, the FFNG was reported to show a superior power conversion efficiency of more than 20%. Other advantages are elasticity, tunability, lightweight, and one-dimensionality, thus offering prospects of exciting technological applications. The FFNG can be made stretchable just by spinning the sheets around an elastic fiber substrate. If woven into fabrics, wearable electronics become thus a very interesting option for FFNG application. Another exciting application is the harvesting of electrical energy from the bloodstream for medical applications. First tests with frog nerves proved to be successful.

The findings are published in  the journal Angewandte Chemie.


How To Produce Massively Nanofibers

Researchers at the University of Georgia (UGA) have developed an inexpensive way to manufacture extraordinarily thin polymer strings commonly known as nanofibers. These polymers can be made from natural materials like proteins or from human-made substances to make plastic, rubber or fiber, including biodegradable materials. The new method, dubbed “magnetospinning” by the researchers, provides a very simple, scalable and safe means for producing very large quantities of nanofibers that can be embedded with a multitude of materials, including live cells and drugs. Many thousands of times thinner than the average human hair, nanofibers are used by medical researchers to create advanced wound dressings—and for tissue regeneration, drug testing, stem cell therapies and the delivery of drugs directly to the site of infection. They are also used in other industries to manufacture fuel cells, batteries, filters and light-emitting screens.

The process we have developed makes it possible for almost anyone to manufacture high-quality nanofibers without the need for expensive equipment,” said Sergiy Minko, study co-author and the Georgia Power Professor of Polymers, Fibers and Textiles in UGA‘s College of Family and Consumer Sciences. “This not only reduces costs, but it also makes it possible for more businesses and researchers to experiment with nanofibers without worrying too much about their budget.”

Currently, the most common nanofiber manufacturing technique—electrospinning—uses high-voltage electricity and specially designed equipment to produce the polymer strings. Equipment operators must have extensive training to use the equipment safely.

In contrast to other nanofiber spinning devices, most of the equipment used in our device is very simple,” Minko said. “Essentially, all you need is a magnet, a syringe and a small motor.”


Nano-Fibers Prevent HIV/AIDS Transmission

Scientists have developed a novel topical microbicide loaded with hyaluronic acid (HA) nanofibers that could potentially prevent transmission of the human immunodeficiency virus (HIV) through the vaginal mucosa. This research is being presented at the 2014 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition, the world’s largest pharmaceutical sciences meeting, in San Diego, Nov. 2-6. HIV is an infectious virus that attacks T lymphocytes, a type of white blood cell that prevents infections and disease. Over time, HIV dramatically depletes the body’s T cell population, leaving the body defenseless against opportunistic pathogens. HIV is transmitted through direct contact with blood, semen, pre-seminal fluid, vaginal fluids, rectal fluids, or breast milk from an infected person. To date, there is no functional cure for HIV infection/AIDS. Currently available anti-HIV drug delivery methods are formulated as gels and suppositories, but can lack appropriate vaginal retention, are prone to medicine leakage, and may cause uncomfortable wetness.
To address these issues, Bi-Botti Youan, Ph.D and his colleagues from University of Missouri-Kansas City School of Pharmacy developed an anti-HIV drug loaded onto a mucoadhesive hyaluronic acid (HA) nanofiber delivery system.
< nanofibersCarnegieMellon

The success of vaginal drug delivery systems depends on the length of time that the drug-containing formulation remains at the site of administration (ex. vagina, rectum). The mucoadhesive nanofibers developed in this study could be beneficial by causing much less discomfort and reducing the dosing frequency simultaneously due to their prolonged retention at the target site,” said Youan.

The nanofiber-based formulation offers various potential advantages in vaginal drug delivery, including the ability to adapt delivery systems for different medical needs, with no leakage or messiness after their application.

Self-Assembled Nanofibers Mimic Living Cells Fibers

Researchers from Carnegie Mellon University have developed a novel method for creating self-assembled protein/polymer nanostructures that are reminiscent of fibers found in living cells. The work offers a promising new way to fabricate materials for drug delivery and tissue engineering applications.

The building blocks of the fibers are a few modified green fluorescent protein (GFP) molecules linked together using a process called click chemistry. An ordinary GFP molecule does not normally bind with other GFP molecules to form fibers.
We have demonstrated that, by adding flexible linkers to protein molecules, we can form completely new types of aggregates. These aggregates can act as a structural material to which you can attach different payloads, such as drugs. In nature, this protein isn’t close to being a structural material,” said Tomasz Kowalewski, professor of chemistry in Carnegie Mellon‘s Mellon College of Science.
But when Carnegie Mellon graduate student Saadyah Averick, working under the guidance of Krzysztof Matyjaszewski, Professor of Chemistry, modified the GFP molecules and attached PEO-dialkyne linkers to them, they noticed something strange — the GFP molecules appeared to self-assemble into long fibers. Importantly, the fibers disassembled after being exposed to sound waves, and then reassembled within a few days. Systems that exhibit this type of reversible fibrous self-assembly have been long sought by scientists for use in applications such as tissue engineering, drug delivery, nanoreactors and imaging.
This was purely curiosity-driven and serendipity-driven work,” Kowalewski said. “But where controlled polymerization and organic chemistry meet biology, interesting things can happen“.
The findings were published in the July 28 issue of Angewandte Chemie International Edition.

NanoFiber Mask Against Lethal Diesel Pollution

When a silver grey haze descends upon Hong Kong in springtime, would you wonder if it is harmful to your lungs? Haze is usually composed of pollutants in the form of tiny suspended particles or fine mists/droplets emitted from vehicles, coal-burning power plants and factories. Continued exposure increases the risk of developing respiratory problems, heart diseases and lung cancer. Can we avoid the unhealthy air? A simple face mask which can block out suspended particles has been developed by scientists from the Department of Mechanical Engineering at The Hong Kong Polytechnic University (PolyU). The project is led by Professor Wallace Woon-Fong Leung, a renowned filtration expert, who has spent his career understanding these invisible killers.

In Hong Kong, suspended particles PM 10 and PM 2.5 are being monitored. PM 10 refers to particles that are 10 microns (or micrometres) in size or smaller, whereas PM 2.5 measures 2.5 microns or smaller.

The nanofibre filter can capture diesel dust effectively
In my view, nano-aerosols (colloid of fine solid particles or liquid droplets of sub-micron to nano-sizes), such as diesel emissions, are the most lethal for three reasons. First, they are in their abundance by number suspended in the air. Second, they are too small to be filtered out using current technologies. Third, they can pass easily through our lungs and work their way into our respiratory systems, and subsequently our vascular, nervous and lymphatic systems, doing the worst kind of harm”, said Professor Leung, At the forefront of combating air pollution. Leung targets ultra-fine pollutants that have yet been picked up by air quality monitors – particles measuring 1 micron or below, which he perceived to be a more important threat to human health.


Purify Blood : A New Easy Cheap Method

A new technique for purifying blood using a nanofiber mesh could prove useful as a cheap, wearable alternative to kidney dialysis.
Kidney failure results in a build up of toxins and excess waste in the body. Dialysis is the most common treatment, performed daily either at home or in hospital. However, dialysis machines require electricity and careful maintenance, and are therefore more readily available in developed countries than poorer nations. Around one million people die each year worldwide from potentially preventable end-stage renal disease.

In addition to this, in the aftermath of disasters such as the Japanese earthquake and tsunami of 2011, dialysis patients are frequently left without treatment until normal hospital services are resumed. With this in mind, Mitsuhiro Ebara and co-workers at the International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science in Ibaraki, Japan, have developed a way of removing toxins and waste from blood using a cheap, easy-to-produce nanofiber mesh1. The mesh could be incorporated into a blood purification product small enough to be worn on a patient’s arm, reducing the need for expensive, time-consuming dialysis.
The team made their nanofiber mesh using two components: a blood-compatible primary matrix polymer made from polyethylene-co-vinyl alchohol, or EVOH, and several different forms of zeolites – naturally occurring aluminosilicates. Zeolites have microporous structures capable of adsorbing toxins such as creatinine from blood.


How To Fix Damaged Hearts

In the U.S., someone suffers a heart attack every 34 seconds — their heart is starved of oxygen and suffers irreparable damage. Engineering new heart tissue in the laboratory that could eventually be implanted into patients could help, and scientists are reporting a promising approach tested with rat cells.

Gordana Vunjak-Novakovic, Rui L. Reis, Ana Martins and colleagues point out that when damaged, adult heart tissue can’t heal itself very well. The only way to fix an injured heart is with a transplant. But within the past decade, interest in regenerating just the lost tissue has surged. The trick is to find materials that, among other things, are nontoxic, won’t get attacked by the body’s immune system and allow for muscle cells to pass the electrical signals necessary for the heart to beat. Previous research has found that chitosan, which is obtained from shrimp and other crustacean shells, nearly fits the bill. In lab tests, scientists have used it as a scaffold for growing heart cells. But it doesn’t transmit electrical signals well. Vunjak-Novakovic’s team decided to build on the chitosan development and coax it to function more like a real heart.
To the chitosan, they added carbon nanofibers, which can conduct electricity, and grew neonatal rat heart cells on the resulting scaffold. After two weeks, cells had filled all the pores and showed far better metabolic and electrical activity than with a chitosan scaffold alone. The cells on the chitosan/carbon scaffold also expressed cardiac genes at higher levels.
The findings have been published in the ACS journal Biomacromolecules.

How To Grow New Brains

A new tool being developed by the University of Texas Arlington (UT Arlington) assistant professor Samarendra Mohanty could help scientists map and track the interactions between neurons inside different areas of the brain. More the development of a fiber-optic, two-photon, optogenetic stimulator and its use on human cells in a laboratory could lead to grew new brains. The tiny tool builds on Mohanty’s previous discovery that near-infrared light can be used to stimulate a light-sensitive protein introduced into living cells and neurons in the brain. This new method could show how different parts of the brain react when a linked area is stimulated.


Scientists have spent a lot of time looking at the physical connections between different regions of the brain. But that information is not sufficient unless we examine how those connections function,” Mohanty said. “That’s where two-photon optogenetics comes into play. This is a tool not only to control the neuronal activity but to understand how the brain works.


Nanoscale ‘Bed of Nails’ for Drug Delivery

Researchers at North Carolina State University have come up with a technique to embed needle-like carbon nanofibers in an elastic membrane, creating a flexible “bed of nails” on the nanoscale that opens the door to development of new drug-delivery systems. The research community is interested in finding new ways to deliver precise doses of drugs to specific targets, such as regions of the brain. One idea is to create balloons embedded with nanoscale spikes that are coated with the relevant drug. Theoretically, the deflated balloon could be inserted into the target area and then inflated, allowing the spikes on the balloon’s surface to pierce the surrounding cell walls and deliver the drug. The balloon could then be deflated and withdrawn.

This image shows carbon nanofibers embedded in the elastic membrane.
We have now developed a way of embedding carbon nanofibers in an elastic silicone membrane and ensuring that the nanofibers are both perpendicular to the membrane’s surface and sturdy enough to impale cells,” says Dr. Anatoli Melechko, an associate professor of materials science and engineering at NC State and co-author of a paper on the work.

Nanofibers Efficient To Prevent HIV And Pregnancy

A University of Washington team has developed a versatile platform to simultaneously offer contraception and prevent HIV. Electrically spun cloth with nanometer-sized fibers can dissolve to release drugs, providing a platform for cheap, discrete and reversible protection. Until now the only way to protect against HIV and unintended pregnancy today is the condom. It’s an effective technology, but not appropriate or popular in all situations.

The electrospun fibers can release chemicals or they can physically block sperm, as shown here.
Our dream is to create a product women can use to protect themselves from HIV infection and unintended pregnancy,” said corresponding author Kim Woodrow, a UW assistant professor of bioengineering. “We have the drugs to do that. It’s really about delivering them in a way that makes them more potent, and allows a woman to want to use it.”

The research was published this week in the Public Library of Science’s open-access journal PLoS One.

Nano-Machines Mimic Human Muscle

Nature manufactures numerous machines known as “molecular”. Highly complex assemblies of proteins, they are involved in essential functions of living beings such as the transport of ions, the synthesis of ATP (the “energy molecule”), and cell division. Our muscles are thus controlled by the coordinated movement of these thousands of protein nano-machines, which only function individually over distances of the order of a nanometer. However, when combined in their thousands, such nano-machines amplify this telescopic movement until they reach our scale and do so in a perfectly coordinated manner.
For the first time, an assembly of thousands of nano-machines capable of producing a coordinated contraction movement extending up to around ten micrometers – thereby amplifying the movement by a factor of 10,000, like the movements of muscular fibers, has been synthesized by a CNRS team from the Institut Charles Sadron – France.

This discovery opens up perspectives for a multitude of applications in robotics, in nanotechnology for the storage of information, in the medical field for the synthesis of artificial muscles or in the design of other materials incorporating nano-machines (endowed with novel mechanical properties).