#Technology blogs Damien cordle

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I Found This Interesting. Joshua Damien Cordle

New computing architecture: Deep learning with light

A new method uses optics to accelerate machine-learning computations on smart speakers and other low-power connected devices

Ask a smart home device for the weather forecast, and it takes several seconds for the device to respond. One reason this latency occurs is because connected devices don't have enough memory or power to store and run the enormous machine-learning models needed for the device to understand what a user is asking of it. The model is stored in a data center that may be hundreds of miles away, where the answer is computed and sent to the device.

MIT researchers have created a new method for computing directly on these devices, which drastically reduces this latency. Their technique shifts the memory-intensive steps of running a machine-learning model to a central server where components of the model are encoded onto light waves.

The waves are transmitted to a connected device using fiber optics, which enables tons of data to be sent lightning-fast through a network. The receiver then employs a simple optical device that rapidly performs computations using the parts of a model carried by those light waves.

This technique leads to more than a hundredfold improvement in energy efficiency when compared to other methods. It could also improve security, since a user's data do not need to be transferred to a central location for computation.

This method could enable a self-driving car to make decisions in real-time while using just a tiny percentage of the energy currently required by power-hungry computers. It could also allow a user to have a latency-free conversation with their smart home device, be used for live video processing over cellular networks, or even enable high-speed image classification on a spacecraft millions of miles from Earth.

"Every time you want to run a neural network, you have to run the program, and how fast you can run the program depends on how fast you can pipe the program in from memory. Our pipe is massive -- it corresponds to sending a full feature-length movie over the internet every millisecond or so. That is how fast data comes into our system. And it can compute as fast as that," says senior author Dirk Englund, an associate professor in the Department of Electrical Engineering and Computer Science (EECS) and member of the MIT Research Laboratory of Electronics.

Joining Englund on the paper is lead author and EECS grad student Alexander Sludds; EECS grad student Saumil Bandyopadhyay, Research Scientist Ryan Hamerly, as well as others from MIT, the MIT Lincoln Laboratory, and Nokia Corporation. The research will be published in Science.

Lightening the load

Neural networks are machine-learning models that use layers of connected nodes, or neurons, to recognize patterns in datasets and perform tasks, like classifying images or recognizing speech. But these models can contain billions of weight parameters, which are numeric values that transform input data as they are processed. These weights must be stored in memory. At the same time, the data transformation process involves billions of algebraic computations, which require a great deal of power to perform.

The process of fetching data (the weights of the neural network, in this case) from memory and moving them to the parts of a computer that do the actual computation is one of the biggest limiting factors to speed and energy efficiency, says Sludds.

"So our thought was, why don't we take all that heavy lifting -- the process of fetching billions of weights from memory -- move it away from the edge device and put it someplace where we have abundant access to power and memory, which gives us the ability to fetch those weights quickly?" he says.

The neural network architecture they developed, Netcast, involves storing weights in a central server that is connected to a novel piece of hardware called a smart transceiver. This smart transceiver, a thumb-sized chip that can receive and transmit data, uses technology known as silicon photonics to fetch trillions of weights from memory each second.

It receives weights as electrical signals and imprints them onto light waves. Since the weight data are encoded as bits (1s and 0s) the transceiver converts them by switching lasers; a laser is turned on for a 1 and off for a 0. It combines these light waves and then periodically transfers them through a fiber optic network so a client device doesn't need to query the server to receive them.

"Optics is great because there are many ways to carry data within optics. For instance, you can put data on different colors of light, and that enables a much higher data throughput and greater bandwidth than with electronics," explains Bandyopadhyay.

Trillions per second

Once the light waves arrive at the client device, a simple optical component known as a broadband "Mach-Zehnder" modulator uses them to perform super-fast, analog computation. This involves encoding input data from the device, such as sensor information, onto the weights. Then it sends each individual wavelength to a receiver that detects the light and measures the result of the computation.

The researchers devised a way to use this modulator to do trillions of multiplications per second, which vastly increases the speed of computation on the device while using only a tiny amount of power.

"In order to make something faster, you need to make it more energy efficient. But there is a trade-off. We've built a system that can operate with about a milliwatt of power but still do trillions of multiplications per second. In terms of both speed and energy efficiency, that is a gain of orders of magnitude," Sludds says.

They tested this architecture by sending weights over an 86-kilometer fiber that connects their lab to MIT Lincoln Laboratory. Netcast enabled machine-learning with high accuracy -- 98.7 percent for image classification and 98.8 percent for digit recognition -- at rapid speeds.

"We had to do some calibration, but I was surprised by how little work we had to do to achieve such high accuracy out of the box. We were able to get commercially relevant accuracy," adds Hamerly.

Moving forward, the researchers want to iterate on the smart transceiver chip to achieve even better performance. They also want to miniaturize the receiver, which is currently the size of a shoe box, down to the size of a single chip so it could fit onto a smart device like a cell phone.

The research is funded, in part, by NTT Research, the National Science Foundation, the Air Force Office of Scientific Research, the Air Force Research Laboratory, and the Army Research Office.

Story Source:

Materials provided by Massachusetts Institute of Technology. Original written by Adam Zewe. Note: Content may be edited for style and length.

Journal Reference:

Alexander Sludds, Saumil Bandyopadhyay, Zaijun Chen, Zhizhen Zhong, Jared Cochrane, Liane Bernstein, Darius Bunandar, P. Ben Dixon, Scott A. Hamilton, Matthew Streshinsky, Ari Novack, Tom Baehr-Jones, Michael Hochberg, Manya Ghobadi, Ryan Hamerly, Dirk Englund. Delocalized photonic deep learning on the internet’s edge. Science, 2022; 378 (6617): 270 DOI: 10.1126/science.abq8271

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I Found This Interesting. Joshua Damien Cordle

Self-powered alarm fights forest fires, monitors environment

Smokey the Bear says that only you can prevent wildfires, but what if Smokey had a high-tech backup? In a new study, a team of Michigan State University scientists designed and fabricated a remote forest fire detection and alarm system powered by nothing but the movement of the trees in the wind.

As detailed in the journal Advanced Functional Materials, the device, known as MC-TENG -- short for multilayered cylindrical triboelectric nanogenerator (TENG) -- generates electrical power by harvesting energy from the sporadic movement of the tree branches from which it hangs.

"As far as we know, this is the first demonstration of such a novel MC-TENG as a forest fire detection system," said lead author Changyong Cao, who directs the Laboratory of Soft Machines and Electronics in MSU's School of Packaging and is an assistant professor in the Packaging School and Departments of Mechanical Engineering, and Electrical and Computer Engineering.

"The self-powered sensing system could continuously monitor the fire and environmental conditions without requiring maintenance after deployment," he said.

For Cao and his team, the tragic forest fires in recent years across the American West, Brazil and Australia were driving forces behind this new technology. Cao believes that early and quick response to forest fires will make the task of extinguishing them easier, significantly reducing the damage and loss of property and life.

Traditional forest fire detection methods include satellite monitoring, ground patrols, watch towers, among others, which have high labor and financial costs in return for low efficiency.

Current remote sensor technologies are becoming more common, but primarily rely on battery technology for power.

"Although solar cells have been widely used for portable electronics or self-powered systems, it is challenging to install these in a forest because of the shading or covering of lush foliage," said Yaokun Pang, co-author and postdoc associate at Cao's lab.

TENG technology converts external mechanical energy -- such as the movement of a tree branch -- into electricity by way of the triboelectric effect, a phenomenon where certain materials become electrically charged after they separate from a second material with which they were previously in contact.

The simplest version of the TENG device consists of two cylindrical sleeves of unique material that fit within one another. The core sleeve is anchored from above while the bottom sleeve is free to slide up and down and move side to side, constrained only by an elastic connective band or spring. As the two sleeves move out of sync, the intermittent loss of contact generates electricity. The MC-TENG are equipped with several hierarchical triboelectric layers, increasing the electrical output.

The MC-TENG stores its sporadically generated electrical current in a carbon-nanotube-based micro supercapacitor. The researchers selected this technology for its rapid charge and discharge times, allowing the device to adequately charge with only short but sustained gusts of wind.

"At a very low vibration frequency, the MC-TENG can efficiently generate electricity to charge the attached supercapacitor in less than three minutes," Cao said.

The researchers outfitted the initial prototype with both carbon monoxide (CO) and temperature sensors. The addition of a temperature sensor was intended to reduce the likelihood of a false positive carbon dioxide reading.

Story Source:

Materials provided by Michigan State University. Note: Content may be edited for style and length.

Journal Reference:

Yaokun Pang, Shoue Chen, Junchi An, Keliang Wang, Yiming Deng, Andre Benard, Nizar Lajnef, Changyong Cao. Multilayered Cylindrical Triboelectric Nanogenerator to Harvest Kinetic Energy of Tree Branches for Monitoring Environment Condition and Forest Fire. Advanced Functional Materials, 2020; 2003598 DOI: 10.1002/adfm.202003598

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Joshua Damien Cordle. I Found This Interesting

Unique material design for brain-like computations

Over the past few decades, computers have seen dramatic progress in processing power; however, even the most advanced computers are relatively rudimentary in comparison with the complexities and capabilities of the human brain.

Researchers at the U.S. Army Combat Capabilities Development Command's Army Research Laboratory say this may be changing as they endeavor to design computers inspired by the human brain's neural structure.

As part of a collaboration with Lehigh University, Army researchers have identified a design strategy for the development of neuromorphic materials.

"Neuromorphic materials is a name given to the material categories or combination of materials that provide both computing and memory capabilities in devices," said Dr. Sina Najmaei, a research scientist and electrical engineer with the laboratory.

Najmaei and his colleagues published a paper, Dynamically reconfigurable electronic and phononic properties in intercalated Hafnium Disulfide (HfS2), in the May 2020 issue of Materials Today.

The neuromorphic computing concept is an in-memory solution that promises orders of magnitude reductions in power consumption over conventional transistors, and is suitable for complex data classification and processing. The limited power efficiency in conventional transistors is a fundamental technology shortcoming impeding future progress in computing.

Neuromorphic materials research conducted over the past 10 years has focused on understanding the unique properties of 2-D materials and their van der Waals multilayered structures.

"The findings show great promise for these materials in electronic applications, but also show the unique interfaces in these materials provide an unprecedented opportunity for design of material properties," Najmaei said.

Over the past four years, the team conducted an effort focused on the design of material properties for high-performance electronic applications.

"Our research led to our Materials Today paper, which expands this effort to design of reconfigurable properties in these materials based on van der Waal/organometallic hybrid systems and neuromorphic material design," Najmaei said.

Neuromorphic computing processes information using new models of computing similar to the brain's cognitive processes.

"In order to process and make rational inferences from the input, information and a new paradigm of computing is needed," Najmaei said. "Neuromorphic hardware with in-memory computer capabilities promises to bridge this ever-growing technology gap."

This research is an important stepping stone towards development of in-memory computing in hybrid devices with unique functional properties for integration in cognitive sensory devices and overcomes significant technical challenges that impede a bottom up approach for streamlining of brain-inspired computing hardware, he said.

If the researchers can ultimately develop a computer that can behave like the brain, it would be extremely useful to the warfighter, Najmaei said.

Neuromorphic computing, like a neural system, would offer computing capability complete with perks, such as robustness to damage, ability to learn, adaptability to change and others. It would have the potential to reduce operational power by a magnitude of 1,000 to 1 million times in comparison to today's computing paradigms.

This level of processing would be highly desirable for image recognition in autonomous systems, and for artificial intelligence in general. Given the significance of AI and autonomous systems in modern day warfare, neuromorphic computing may very well be a cornerstone for a wide range of future leap-ahead warfighting capabilities, Najmaei said.

Story Source:

Materials provided by U.S. Army Research Laboratory. Note: Content may be edited for style and length.

Journal Reference:

Sina Najmaei, Chinedu E. Ekuma, Adam A. Wilson, Asher C. Leff, Madan Dubey. Dynamically reconfigurable electronic and phononic properties in intercalated HfS2. Materials Today, 2020; DOI: 10.1016/j.mattod.2020.04.030

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Joshua Damien Cordle. I Found This Interesting.

World's first spherical artificial eye has 3D retina

An international team led by scientists at the Hong Kong University of Science and Technology (HKUST) has recently developed the world's first 3D artificial eye with capabilities better than existing bionic eyes and in some cases, even exceed those of the human eyes, bringing vision to humanoid robots and new hope to patients with visual impairment.

Scientists have spent decades trying to replicate the structure and clarity of a biological eye, but vision provided by existing prosthetic eyes -- largely in the form of spectacles attached with external cables, are still in poor resolution with 2D flat image sensors. The Electrochemical Eye (EC-Eye) developed at HKUST, however, not only replicates the structure of a natural eye for the first time, but may actually offer sharper vision than a human eye in the future, with extra functions such as the ability to detect infrared radiation in darkness.

The key feature allowing such breakthroughs is a 3D artificial retina -- made of an array of nanowire light sensors which mimic the photoreceptors in human retinas. Developed by Prof. FAN Zhiyong and Dr. GU Leilei from the Department of Electronic and Computer Engineering at HKUST, the team connected the nanowire light sensors to a bundle of liquid-metal wires serving as nerves behind the human-made hemispherical retina during the experiment, and successfully replicated the visual signal transmission to reflect what the eye sees onto the computer screen.

In the future, those nanowire light sensors could be directly connected to the nerves of the visually impaired patients. Unlike in a human eye where bundles of optic nerve fibers (for signal transmission) need to route through the retina via a pore -- from the front side of the retina to the backside (thus creating a blind spot in human vision) before reaching the brain; the light sensors that now scatters across the entire human-made retina could each feed signals through its own liquid-metal wire at the back, thereby eliminating the blind spot issue as they do not have to route through a single spot.

Apart from that, as nanowires have even higher density than photoreceptors in human retina, the artificial retina can thus receive more light signals and potentially attain a higher image resolution than human retina -- if the back contacts to individual nanowires are made in the future. With different materials used to boost the sensors' sensitivity and spectral range, the artificial eye may also achieve other functions such as night vision.

"I have always been a big fan of science fiction, and I believe many technologies featured in stories such as those of intergalactic travel, will one day become reality. However, regardless of image resolution, angle of views or user-friendliness, the current bionic eyes are still of no match to their natural human counterpart. A new technology to address these problems is in urgent need, and it gives me a strong motivation to start this unconventional project," said Prof. Fan, whose team has spent nine years to complete the current study from idea inception.

The team collaborated with the University of California, Berkeley on this project and their findings were recently published in the journal Nature.

"In the next step, we plan to further improve the performance, stability and biocompatibility of our device. For prosthesis application, we look forward to collaborating with medical research experts who have the relevant expertise on optometry and ocular prosthesis," Prof. Fan added.

The working principle of the artificial eye involves an electrochemical process which is adopted from a type of solar cell. In principle, each photo sensor on the artificial retina can serve as a nanoscale solar cell. With further modification, the EC-Eye can be a self-powered image sensor, so there is no need for external power source nor circuitry when used for ocular prosthesis, which will be much more user-friendly as compared with the current technology.

Story Source:

Materials provided by Hong Kong University of Science and Technology. Note: Content may be edited for style and length.

Journal Reference:

Leilei Gu, Swapnadeep Poddar, Yuanjing Lin, Zhenghao Long, Daquan Zhang, Qianpeng Zhang, Lei Shu, Xiao Qiu, Matthew Kam, Ali Javey, Zhiyong Fan. A biomimetic eye with a hemispherical perovskite nanowire array retina. Nature, 2020; 581 (7808): 278 DOI: 10.1038/s41586-020-2285-x

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I Found This Interesting. Joshua Damien Cordle

A new way to turn heat into useful energy

An international team of scientists has figured out how to capture heat and turn it into electricity.

The discovery, published last week in the journal Science Advances, could create more efficient energy generation from heat in things like car exhaust, interplanetary space probes and industrial processes.

"Because of this discovery, we should be able to make more electrical energy out of heat than we do today," said study co-author Joseph Heremans, professor of mechanical and aerospace engineering and Ohio Eminent Scholar in Nanotechnology at The Ohio State University. "It's something that, until now, nobody thought was possible."

The discovery is based on tiny particles called paramagnons -- bits that are not quite magnets, but that carry some magnetic flux. This is important, because magnets, when heated, lose their magnetic force and become what is called paramagnetic. A flux of magnetism -- what scientists call "spins" -- creates a type of energy called magnon-drag thermoelectricity, something that, until this discovery, could not be used to collect energy at room temperature.

"The conventional wisdom was once that, if you have a paramagnet and you heat it up, nothing happens," Heremans said. "And we found that that is not true. What we found is a new way of designing thermoelectric semiconductors -- materials that convert heat to electricity. Conventional thermoelectrics that we've had over the last 20 years or so are too inefficient and give us too little energy, so they are not really in widespread use. This changes that understanding."

Magnets are a crucial part of collecting energy from heat: When one side of a magnet is heated, the other side -- the cold side -- gets more magnetic, producing spin, which pushes the electrons in the magnet and creates electricity.

The paradox, though, is that when magnets get heated up, they lose most of their magnetic properties, turning them into paramagnets -- "almost-but-not-quite magnets," Heremans calls them. That means that, until this discovery, nobody thought of using paramagnets to harvest heat because scientists thought paramagnets weren't capable of collecting energy.

What the research team found, though, is that the paramagnons push the electrons only for a billionth of a millionth of a second -- long enough to make paramagnets viable energy-harvesters.

The research team -- an international group of scientists from Ohio State, North Carolina State University and the Chinese Academy of Sciences (all are equal authors on this journal article) -- started testing paramagnons to see if they could, under the right circumstances, produce the necessary spin.

What they found, Heremans said, is that paramagnons do, in fact, produce the kind of spin that pushes electrons.

And that, he said, could make it possible to collect energy.

Ohio State graduate student Yuanhua Zheng is also an author on this work. The research was conducted in partnership with additional researchers at the U.S. Department of Energy's Oak Ridge National Laboratory and was supported by the National Science Foundation, the Air Force Office of Scientific Research and the U.S. Department of Energy.

make a difference: sponsored opportunity

Story Source:

Materials provided by Ohio State University. Original written by Laura Arenschield. Note: Content may be edited for style and length.

Journal Reference:

Y. Zheng, T. Lu, Md M. H. Polash, M. Rasoulianboroujeni, N. Liu, M. E. Manley, Y. Deng, P. J. Sun, X. L. Chen, R. P. Hermann, D. Vashaee, J. P. Heremans, H. Zhao. Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe. Science Advances, 2019; 5 (9): eaat9461 DOI: 10.1126/sciadv.aat9461

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I Found This Interesting. Joshua Damien Cordle

Portable electronics: A stretchable and flexible biofuel cell that runs on sweat

A unique new flexible and stretchable device, worn against the skin and capable of producing electrical energy by transforming the compounds present in sweat, was recently developed and patented by CNRS researchers from l'Université Grenoble Alpes and the University of San Diego (USA). This cell is already capable of continuously lighting an LED, opening new avenues for the development of wearable electronics powered by autonomous and environmentally friendly biodevices. This research was published in Advanced Functional Materials on September 25, 2019.

The potential uses for wearable electronic devices continue to increase, especially for medical and athletic monitoring. Such devices require the development of a reliable and efficient energy source that can easily be integrated into the human body. Using "biofuels" present in human organic liquids has long been a promising avenue.

Scientists from the Département de chimie moléculaire (CNRS/Université Grenoble Alpes), who specialize in bioelectrochemistry, decided to collaborate with an American team from the University of San Diego in California, who are experts in nanomachines, biosensors, and nanobioelectronics. Together they developed a flexible conductive material consisting of carbon nanotubes, crosslinked polymers, and enzymes joined by stretchable connectors that are directly printed onto the material through screen-printing.

The biofuel cell, which follows deformations in the skin, produces electrical energy through the reduction of oxygen and the oxidation of the lactate present in perspiration. Once applied to the arm, it uses a voltage booster to continuously power an LED. It is relatively simple and inexpensive to produce, with the primary cost being the production of the enzymes that transform the compounds found in sweat. The researchers are now seeking to amplify the voltage provided by the biofuel cell in order to power larger portable devices.

Patents:

F. Giroud, A. J. Gross, S. Cosnier. Bioelectrode for the detection and/or oxidation of glucose and its manufacturing process and device comprising it. French patent n° 1662997 submitted December 21, 2016 . Published 22 June 2018. Extension PCT n°PCT/FR2017053689 submitted December 21, 2017. Published PCT n° WO2018115710A1 28 June 2018.. Applicants: CNRS

S. Cosnier, R. Haddad. Electrochemical reactor block. French patent n° 1559069 submitted September 25, 2015 ; n°3041819. Published March 31, 2017. Extension Europe, USA, Japan n°16777723.4 ; FR20160552310 ; submitted September 14, 2016.. Applicants: Université Joseph Fourier and CNRS

Story Source:

Materials provided by CNRS. Note: Content may be edited for style and length.

Journal Reference:

Xiaohong Chen, Lu Yin, Jian Lv, Andrew J. Gross, Minh Le, Nathaniel Georg Gutierrez, Yang Li, Itthipon Jeerapan, Fabien Giroud, Anastasiia Berezovska, Rachel K. O’Reilly, Sheng Xu, Serge Cosnier, and Joseph Wang. Stretchable and Flexible Buckypaper-Based Lactate Biofuel Cell for Wearable Electronics. Advanced Functional Materials, 2019 DOI: 10.1002/adfm.201905785

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I Found This Interesting. Joshua Damien Cordle

Wearable sensors detect what's in your sweat

Needle pricks not your thing? A team of scientists at the University of California, Berkeley, is developing wearable skin sensors that can detect what's in your sweat.

They hope that one day, monitoring perspiration could bypass the need for more invasive procedures like blood draws, and provide real-time updates on health problems such as dehydration or fatigue.

In a paper appearing today (Friday, August 16) in Science Advances, the team describes a new sensor design that can be rapidly manufactured using a "roll-to-roll" processing technique that essentially prints the sensors onto a sheet of plastic like words on a newspaper.

They used the sensors to monitor the sweat rate, and the electrolytes and metabolites in sweat, from volunteers who were exercising, and others who were experiencing chemically induced perspiration.

"The goal of the project is not just to make the sensors but start to do many subject studies and see what sweat tells us -- I always say 'decoding' sweat composition," said Ali Javey, a professor of electrical engineering and computer science at UC Berkeley and senior author on the paper.

"For that we need sensors that are reliable, reproducible, and that we can fabricate to scale so that we can put multiple sensors in different spots of the body and put them on many subjects," said Javey, who also serves as a faculty scientist at Lawrence Berkeley National Laboratory.

The new sensors contain a spiraling microscopic tube, or microfluidic, that wicks sweat from the skin. By tracking how fast the sweat moves through the microfluidic, the sensors can report how much a person is sweating, or their sweat rate.

The microfluidics are also outfitted with chemical sensors that can detect concentrations of electrolytes like potassium and sodium, and metabolites like glucose.

Javey and his team worked with researchers at the VTT Technical Research Center of Finland to develop a way to quickly manufacture the sensor patches in a roll-to-roll processing technique similar to screen printing.

"Roll-to-roll processing enables high-volume production of disposable patches at low cost," Jussi Hiltunen of VTT said. "Academic groups gain significant benefit from roll-to-roll technology when the number of test devices is not limiting the research. Additionally, up-scaled fabrication demonstrates the potential to apply the sweat-sensing concept in practical applications."

To better understand what sweat can say about the real-time health of the human body, the researchers first placed the sweat sensors on different spots on volunteers' bodies -- including the forehead, forearm, underarm and upper back -- and measured their sweat rates and the sodium and potassium levels in their sweat while they rode on an exercise bike.

They found that local sweat rate could indicate the body's overall liquid loss during exercise, meaning that tracking sweat rate might be a way to give athletes a heads up when they may be pushing themselves too hard.

"Traditionally what people have done is they would collect sweat from the body for a certain amount of time and then analyze it," said Hnin Yin Yin Nyein, a graduate student in materials science and engineering at UC Berkeley and one of the lead authors on the paper. "So you couldn't really see the dynamic changes very well with good resolution. Using these wearable devices we can now continuously collect data from different parts of the body, for example to understand how the local sweat loss can estimate whole-body fluid loss."

They also used the sensors to compare sweat glucose levels and blood glucose levels in healthy and diabetic patients, finding that a single sweat glucose measurement cannot necessarily indicate a person's blood glucose level.

"There's been a lot of hope that non-invasive sweat tests could replace blood-based measurements for diagnosing and monitoring diabetes, but we've shown that there isn't a simple, universal correlation between sweat and blood glucose levels," said Mallika Bariya, a graduate student in materials science and engineering at UC Berkeley and the other lead author on the paper. "This is important for the community to know, so that going forward we focus on investigating individualized or multi-parameter correlations."

This work was supported by the NSF Nanomanufacturing Systems for Mobile Computing and Mobile Energy Technologies (NASCENT), the Berkeley Sensor and Actuator Center (BSAC), and the Bakar fellowship.

Story Source:

Materials provided by University of California - Berkeley. Original written by Kara Manke. Note: Content may be edited for style and length.

Related Multimedia:

YouTube video: A sweat sensor to monitor your health

Journal Reference:

Hnin Yin Yin Nyein, Mallika Bariya, Liisa Kivimäki, Sanna Uusitalo, Tiffany Sun Liaw, Elina Jansson, Christine Heera Ahn, John A. Hangasky, Jiangqi Zhao, Yuanjing Lin, Tuomas Happonen, Minghan Chao, Christina Liedert, Yingbo Zhao, Li-Chia Tai, Jussi Hiltunen, Ali Javey. Regional and correlative sweat analysis using high-throughput microfluidic sensing patches toward decoding sweat. Science Advances, 2019; 5 (8): eaaw9906 DOI: 10.1126/sciadv.aaw9906

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I Found This Interesting. Joshua Damien Cordle

Lasers enable engineers to weld ceramics, no furnace required

Smartphones that don't scratch or shatter. Metal-free pacemakers. Electronics for space and other harsh environments. These could all be made possible thanks to a new ceramic welding technology developed by a team of engineers at the University of California San Diego and the University of California Riverside.

The process, published in the Aug. 23 issue of Science, uses an ultrafast pulsed laser to melt ceramic materials along the interface and fuse them together. It works in ambient conditions and uses less than 50 watts of laser power, making it more practical than current ceramic welding methods that require heating the parts in a furnace.

Ceramics have been fundamentally challenging to weld together because they need extremely high temperatures to melt, exposing them to extreme temperature gradients that cause cracking, explained senior author Javier E. Garay, a professor of mechanical engineering and materials science and engineering at UC San Diego, who led the work in collaboration with UC Riverside professor and chair of mechanical engineering Guillermo Aguilar.

Ceramic materials are of great interest because they are biocompatible, extremely hard and shatter resistant, making them ideal for biomedical implants and protective casings for electronics. However, current ceramic welding procedures are not conducive to making such devices.

"Right now there is no way to encase or seal electronic components inside ceramics because you would have to put the entire assembly in a furnace, which would end up burning the electronics," Garay said.

Garay, Aguilar and colleagues' solution was to aim a series of short laser pulses along the interface between two ceramic parts so that heat builds up only at the interface and causes localized melting. They call their method ultrafast pulsed laser welding.

To make it work, the researchers had to optimize two aspects: the laser parameters (exposure time, number of laser pulses, and duration of pulses) and the transparency of the ceramic material. With the right combination, the laser energy couples strongly to the ceramic, allowing welds to be made using low laser power (less than 50 watts) at room temperature.

"The sweet spot of ultrafast pulses was two picoseconds at the high repetition rate of one megahertz, along with a moderate total number of pulses. This maximized the melt diameter, minimized material ablation, and timed cooling just right for the best weld possible," Aguilar said.

"By focusing the energy right where we want it, we avoid setting up temperature gradients throughout the ceramic, so we can encase temperature-sensitive materials without damaging them," Garay said.

As a proof of concept, the researchers welded a transparent cylindrical cap to the inside of a ceramic tube. Tests showed that the welds are strong enough to hold vacuum.

"The vacuum tests we used on our welds are the same tests that are used in industry to validate seals on electronic and optoelectronic devices," said first author Elias Penilla, who worked on the project as a postdoctoral researcher in Garay's research group at UC San Diego.

The process has so far only been used to weld small ceramic parts that are less than two centimeters in size. Future plans will involve optimizing the method for larger scales, as well as for different types of materials and geometries.

Story Source:

Materials provided by University of California - San Diego. Original written by Liezel Labios. Note: Content may be edited for style and length.

Journal Reference:

E. H. Penilla, L. F. Devia-Cruz, A. T. Wieg, P. Martinez-Torres, N. Cuando-Espitia, P. Sellappan, Y. Kodera, G. Aguilar, J. E. Garay. Ultrafast Laser Welding of Ceramics. Science, 2019 DOI: 10.1126/science.aaw6699

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I Found This Interesting. Joshua Damien Cordle

Laser printing tech

The next generation of waterproof smart fabrics will be laser printed and made in minutes. That's the future imagined by the researchers behind new e-textile technology.

Scientists from RMIT University in Melbourne, Australia, have developed a cost-efficient and scaleable method for rapidly fabricating textiles that are embedded with energy storage devices.

In just three minutes, the method can produce a 10x10cm smart textile patch that's waterproof, stretchable and readily integrated with energy harvesting technologies.

The technology enables graphene supercapacitors -- powerful and long-lasting energy storage devices that are easily combined with solar or other sources of power -- to be laser printed directly onto textiles.

In a proof-of-concept, the researchers connected the supercapacitor with a solar cell, delivering an efficient, washable and self-powering smart fabric that overcomes the key drawbacks of existing e-textile energy storage technologies.

The growing smart fabrics industry has diverse applications in wearable devices for the consumer, health care and defence sectors -- from monitoring vital signs of patients, to tracking the location and health status of soldiers in the field, and monitoring pilots or drivers for fatigue.

Dr Litty Thekkakara, a researcher in RMIT's School of Science, said smart textiles with built-in sensing, wireless communication or health monitoring technology called for robust and reliable energy solutions.

"Current approaches to smart textile energy storage, like stitching batteries into garments or using e-fibres, can be cumbersome and heavy, and can also have capacity issues," Thekkakara said.

"These electronic components can also suffer short-circuits and mechanical failure when they come into contact with sweat or with moisture from the environment.

"Our graphene-based supercapacitor is not only fully washable, it can store the energy needed to power an intelligent garment -- and it can be made in minutes at large scale.

"By solving the energy storage-related challenges of e-textiles, we hope to power the next generation of wearable technology and intelligent clothing."

The research analysed the performance of the proof-of-concept smart textile across a range of mechanical, temperature and washability tests and found it remained stable and efficient.

RMIT Honorary Professor and Distinguished Professor at the University of Shanghai for Science and Technology, Min Gu, said the technology could enable real-time storage of renewable energies for e-textiles.

"It also opens the possibility for faster roll-to-roll fabrication, with the use of advanced laser printing based on multifocal fabrication and machine learning techniques," Gu said.

The researchers have applied for a patent for the new technology, which was developed with support from RMIT Seed Fund and Design Hub project grants.

Story Source:

Materials provided by RMIT University. Note: Content may be edited for style and length.

Journal Reference:

Litty V. Thekkekara, Min Gu. Large-scale waterproof and stretchable textile-integrated laser- printed graphene energy storages. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-48320-z

[damiencordle]

I Found This Interesting. Joshua Damien Cordle

A wearable device so thin and soft you won't even notice it

Wearable human-machine interfaces -- devices that can collect and store important health information about the wearer, among other uses -- have benefited from advances in electronics, materials and mechanical designs. But current models still can be bulky and uncomfortable, and they can't always handle multiple functions at one time.

Researchers reported Friday, Aug. 2, the discovery of a multifunctional ultra-thin wearable electronic device that is imperceptible to the wearer.

The device allows the wearer to move naturally and is less noticeable than wearing a Band-Aid, said Cunjiang Yu, Bill D. Cook Associate Professor of Mechanical Engineering at the University of Houston and lead author for the paper, published as the cover story in Science Advances.

"Everything is very thin, just a few microns thick," said Yu, who also is a principal investigator at the Texas Center for Superconductivity at UH. "You will not be able to feel it."

It has the potential to work as a prosthetic skin for a robotic hand or other robotic devices, with a robust human-machine interface that allows it to automatically collect information and relay it back to the wearer.

That has applications for health care -- "What if when you shook hands with a robotic hand, it was able to instantly deduce physical condition?" Yu asked -- as well as for situations such as chemical spills, which are risky for humans but require human decision-making based on physical inspection.

While current devices are gaining in popularity, the researchers said they can be bulky to wear, offer slow response times and suffer a drop in performance over time. More flexible versions are unable to provide multiple functions at once -- sensing, switching, stimulation and data storage, for example -- and are generally expensive and complicated to manufacture.

The device described in the paper, a metal oxide semiconductor on a polymer base, offers manufacturing advantages and can be processed at temperatures lower than 300 C.

"We report an ultrathin, mechanically imperceptible, and stretchable (human-machine interface) HMI device, which is worn on human skin to capture multiple physical data and also on a robot to offer intelligent feedback, forming a closed-loop HMI," the researchers wrote. "The multifunctional soft stretchy HMI device is based on a one-step formed, sol-gel-on-polymer-processed indium zinc oxide semiconductor nanomembrane electronics."

Video: https://www.youtube.com/watch?time_continue=3&v=kC5gtHH33Lw

Story Source:

Materials provided by University of Houston. Original written by Jeannie Kever. Note: Content may be edited for style and length.

Journal Reference:

Kyoseung Sim, Zhoulyu Rao, Zhanan Zou, Faheem Ershad, Jianming Lei, Anish Thukral, Jie Chen, Qing-An Huang, Jianliang Xiao and Cunjiang Yu. Metal oxide semiconductor nanomembrane–based soft unnoticeable multifunctional electronics for wearable human-machine interfaces. Science Advances, 2019 DOI: 10.1126/sciadv.aav9653