Red wine may hold the key to next-gen wearable technology

Red wine may hold the key to next-gen wearable technology:

Extracting tannic acid from red wine, coffee or black tea, led a team of scientists from the University of Manchester to develop much more durable and flexible wearable devices. The addition of tannins improved mechanical properties of materials such as cotton to develop wearable sensors for rehabilitation monitoring, drastically increasing the devices lifespan.

The team have developed wearable devices such as capacitive breath sensors and artificial hands for extreme conditions by improving the durability of flexible sensors. Previously, wearable technology has been subject to fail after repeated bending and folding which can interrupt the conductivity of such devices due to tiny micro cracks. Improving this could open the door to more long-lasting integrated technology.

Dr. Xuqing Liu who led the research team said: "We are using this method to develop new flexible, breathable, wearable devices. The main research objective of our group is to develop comfortable wearable devices for flexible human-machine interface.

"Traditional conductive material suffers from weak bonding to the fibers which can result in low conductivity. When red wine, or coffee, or black tea, is sprinkled on dress, it will be difficult to get rid of these stains. The main reason is that they all contain tannic acid, which can firmly adsorb the material on the surface of the fiber. This good adhesion is exactly what we need for durable wearable, conductive devices."

The new research published in the journal Small demonstrated that without this layer of tannic acid, the conductivity is several hundred times, or even thousands of times, less than traditional conductive material samples as the conductive coating becomes easily detached from the textile surface through repeated bending and flexing.

The team used commercially available tannins but also tried to immerse the fabric directly in red wine, black tea and black coffee solutions where they saw the same results. The overall impact of this new method could see a reduction in price for wearable technology along with improvements in comfort and robustness.

The improved conductivity using natural sources can allow technology developers to use more comfortable fabrics, such as cotton, to replace nylon, which is stiff and uncomfortable. The technology can also allow for circuits to be printed directly on to the surface of clothing to make a comfortable, flexible circuit board.

Due to the strong adsorption of tannic acid, the surface conductive coating has good durability, and the developed wearable devices maintain excellent performance after bending, folding and stretching.

Source: Nano Magazine

Waste heat from electronics can be converted into reusable energy more efficiently

Waste heat from electronics can be converted into reusable energy more efficiently:

Waste heat from electronics can be converted into reusable energy more efficiently thanks to a collaboration between the University of Texas at Dallas and Texas Instruments.

The collaborative project demonstrated that silicon’s ability to harvest energy from heat can be greatly increased while remaining mass-producible.

Dr. Mark Lee, professor and head of the Department of Physics in the School of Natural Sciences and Mathematics, is the corresponding author of a study published in Nature Electronics that describes the results. The findings could greatly influence how circuits are cooled in electronics, as well as provide a method of powering IoT sensors.

“Sensors go everywhere now. They can’t be constantly plugged in, so they must consume very little power,” Lee said. “Without a reliable light source for photovoltaic energy, you’re left needing some kind of battery, one that shouldn’t have to be replaced.”

One solution is thermoelectric generation which converts a difference in temperature into electrical energy, but the primary hurdles for widespread thermoelectric harvesting have been efficiency and cost.

“Thermoelectric generation has been expensive, both in terms of cost per device and cost per watt of energy generated,” Lee said in a statement. “The best materials are fairly exotic – they’re either rare or toxic – and they aren’t easily made compatible with basic semiconductor technology.”

Silicon is a poor thermoelectric material in its bulk, crystalline form but research has indicated that it performs much better as a nanowire, a filamentlike shape with two of its three dimensions less than 100nm.

“In the decade since those experiments, however, efforts to make a useful silicon thermoelectric generator haven’t succeeded,” Lee said.

One barrier is that the nanowire is too small to be compatible with chip-manufacturing processes. To overcome this, Lee and his team relied on so-called nanoblades, which are 80nm thick but more than eight times that in width, which makes them compatible with chip-manufacturing rules. Study co-author Hal Edwards, a TI Fellow at Texas Instruments, designed and supervised fabrication of the prototype devices.

Lee explained that the nanoblade shape loses some thermoelectric ability relative to the nanowire.

“However, using many at once can generate about as much power as the best exotic materials, with the same area and temperature difference,” he said.

One key realisation was that some previous attempts failed because too much material was used. “When you use too much silicon, the temperature differential that feeds the generation drops,” Lee said. “Too much waste heat is used, and, as that hot-to-cold margin drops, you can’t generate as much thermoelectric power. There is a sweet spot that, with our nanoblades, we’re much closer to finding than anyone else. The change in the form of silicon studied changed the game.”

Lee said that the advanced silicon-processing technology at Texas Instruments allows for efficient, inexpensive manufacturing of a huge number of the devices.

“You can live with a 40 per cent reduction in thermoelectric ability relative to exotic materials because your cost per watt generated plummets,” he said. “The marginal cost is a factor of 100 lower.”

Artificial throat could someday help mute people ‘speak'

Artificial throat could someday help mute people ‘speak’:

Most people take speech for granted, but it’s actually a complex process that involves both motions of the mouth and vibrations of folded tissues, called vocal cords, within the throat. If the vocal cords sustain injuries or other lesions, a person can lose the ability to speak. Now, researchers reporting in ACS Nano have developed a wearable artificial throat that, when attached to the neck like a temporary tattoo, can transform throat movements into sounds.

Scientists have developed detectors that measure movements on human skin, such as pulse or heartbeat. However, the devices typically can’t convert these motions into sounds. Recently, He Tian, Yi Yang, Tian-Ling Ren and colleagues developed a prototype artificial throat with both capabilities, but because the device needed to be taped to the skin, it wasn’t comfortable enough to wear for long periods of time. So the researchers wanted to develop a thinner, skin-like artificial throat that would adhere to the neck like a temporary tattoo.

To make their artificial throat, the researchers laser-scribed graphene on a thin sheet of polyvinyl alcohol film. The flexible device measured 0.6 by 1.2 inches, or about double the size of a person’s thumbnail. The researchers used water to attach the film to the skin over a volunteer’s throat and connected it with electrodes to a small armband that contained a circuit board, microcomputer, power amplifier and decoder. When the volunteer noiselessly imitated the throat motions of speech, the instrument converted these movements into emitted sounds, such as the words “OK” and “No.” The researchers say that, in the future, mute people could be trained to generate signals with their throats that the device would translate into speech.

The authors acknowledge funding from the National Key R&D Program of China, the National Natural Science Foundation of China, the National Basic Research Program of China, the Beijing Innovation Center for Future Chip, the Beijing Natural Science Foundation and the Shenzhen Science and Technology Program.

Source: Nano Magazine

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Researchers repair faulty brain circuits using nanotechnology:

Working with mouse and human tissue, Johns Hopkins Medicine researchers report new evidence that a protein pumped out of some — but not all — populations of “helper” cells in the brain, called astrocytes, plays a specific role in directing the formation of connections among neurons needed for learning and forming new memories.

Using mice genetically engineered and bred with fewer such connections, the researchers conducted proof-of-concept experiments that show they could deliver corrective proteins via nanoparticles to replace the missing protein needed for “road repairs” on the defective neural highway.

Since such connective networks are lost or damaged by neurodegenerative diseases such as Alzheimer’s or certain types of intellectual disability, such as Norrie disease, the researchers say their findings advance efforts to regrow and repair the networks and potentially restore normal brain function. The findings are described in the May issue of Nature Neuroscience.

In the brain, astrocytes are the support cells that act as guides to direct new cells, promote chemical signaling, and clean up byproducts of brain cell metabolism.

Rothstein’s team focused on a particular astrocyte protein, glutamate transporter-1, which previous studies suggested was lost from astrocytes in certain parts of brains with neurodegenerative diseases. Like a biological vacuum cleaner, the protein normally sucks up the chemical “messenger” glutamate from the spaces between neurons after a message is sent to another cell, a step required to end the transmission and prevent toxic levels of glutamate from building up.

When these glutamate transporters disappear from certain parts of the brain –such as the motor cortex and spinal cord in people with amyotrophic lateral sclerosis (ALS) –glutamate hangs around much too long, sending messages that overexcite and kill the cells.

To figure out how the brain decides which cells need the glutamate transporters, Rothstein and colleagues focused on the region of DNA in front of the gene that typically controls the on-off switch needed to manufacture the protein. They genetically engineered mice to glow red in every cell where the gene is activated.

Normally, the glutamate transporter is turned on in all astrocytes. But, by using between 1,000- and 7,000-bit segments of DNA code from the on-off switch for glutamate, all the cells in the brain glowed red, including the neurons. It wasn’t until the researchers tried the largest sequence of an 8,300-bit DNA code from this location that the researchers began to see some selection in red cells. These red cells were all astrocytes but only in certain layers of the brain’s cortex in mice.

Because they could identify these “8.3 red astrocytes,” the researchers thought they might have a specific function different than other astrocytes in the brain. To find out more precisely what these 8.3 red astrocytes do in the brain, the researchers used a cell-sorting machine to separate the red astrocytes from the uncolored ones in mouse brain cortical tissue, and then identified which genes were turned on to much higher than usual levels in the red compared to the uncolored cell populations. The researchers found that the 8.3 red astrocytes turn on high levels of a gene that codes for a different protein known as Norrin.

Rothstein’s team took neurons from normal mouse brains, treated them with Norrin, and found that those neurons grew more of the “branches” — or extensions — used to transmit chemical messages among brain cells. Then, Rothstein says, the researchers looked at the brains of mice engineered to lack Norrin, and saw that these neurons had fewer branches than in healthy mice that made Norrin.

In another set of experiments, the research team took the DNA code for Norrin plus the 8,300 “location” DNA and assembled them into deliverable nanoparticles. When they injected the Norrin nanoparticles into the brains of mice engineered without Norrin, the neurons in these mice began to quickly grow many more branches, a process suggesting repair to neural networks. They repeated these experiments with human neurons too.

Rothstein notes that mutations in the Norrin protein that reduce levels of the protein in people cause Norrie disease — a rare, genetic disorder that can lead to blindness in infancy and intellectual disability. Because the researchers were able to grow new branches for communication, they believe it may one day be possible to use Norrin to treat some types of intellectual disabilities such as Norrie disease.

Source: Nano Magazine

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