Smart windows get darker to filter out the sun’s rays on bright days, and turn clear on cloudy days to let more light in. This feature can help control indoor temperatures and offers some privacy without resorting to aids such as mini-blinds.Now scientists report a new development in this growing niche: solar smart windows that can turn opaque on demand and even power other devices. The study appears in ACS Photonics (“Electrically Controllable Light Trapping for Self-Powered Switchable Solar Windows”).
Smart windows get darker to filter out the sun’s rays on bright days, and turn clear on cloudy days to let more light in. This feature can help control indoor temperatures and offers some privacy without resorting to mini-blinds. Now scientists report a new development in this growing niche: solar smart windows that can turn opaque on demand and even power other devices.
|Most existing solar-powered smart windows are designed to respond automatically to changing conditions, such as light or heat. But this means that on cool or cloudy days, consumers can’t flip a switch and tint the windows for privacy.|
|Also, these devices often operate on a mere fraction of the light energy they are exposed to while the rest gets absorbed by the windows. This heats them up, which can add warmth to a room that the windows are supposed to help keep cool. Jeremy Munday and colleagues wanted to address these limitations.|
|The researchers created a new smart window by sandwiching a polymer matrix containing microdroplets of liquid crystal materials, and an amorphous silicon layer — the type often used in solar cells — between two glass panes.
When the window is “off,” the liquid crystals scatter light, making the glass opaque. The silicon layer absorbs the light and provides the low power needed to align the crystals so light can pass through and make the window transparent when the window is turned “on” by the user.
|The extra energy that doesn’t go toward operating the window is harvested and could be redirected to power other devices, such as lights, TVs or smartphones, the researchers say.|
|Source: American Chemical Society|
|“By combining these two cells, the perovskite cell and the silicon cell, we are able to make much better use of the solar energy and achieve higher efficiencies than either cell on its own.”
Researchers at The Australian National University (ANU) have found a new way to fabricate high efficiency semi-transparent perovskite solar cells in a breakthrough that could lead to more efficient and cheaper solar electricity (Advanced Energy Materials, “Efficient Indium-Doped TiOxElectron Transport Layers for High-Performance Perovskite Solar Cells and Perovskite-Silicon Tandems”).
|Dr Tom White from the ANU Research School of Engineering said the new fabrication method significantly improved the performance of perovskite solar cells, which can combine with conventional silicon solar cells to produce more efficient solar electricity.|
|ANU Ph.D. student The Duong, Dr.Tom White and Ph.D. student Jun Peng.|
|He said perovskite solar cells were extremely good at making electricity from visible light – blue, green and red – while conventional silicon solar cells were more efficient at converting infrared light into electricity.|
|“The prospect of adding a few additional processing steps at the end of a silicon cell production line to make perovskite cells is very exciting and could boost solar efficiency from 25 per cent to 30 per cent,” Dr White said.|
|“By combining these two cells, the perovskite cell and the silicon cell, we are able to make much better use of the solar energy and achieve higher efficiencies than either cell on its own.”|
|While perovskite cells can improve efficiency, they are not yet stable enough to be used on rooftops. Dr White said the new fabrication technique could help develop more reliable perovskite cells.|
|The new fabrication method involves adding a small amount of the element indium into one of the cell layers during fabrication. That could increase the cell’s power output by as much as 25 per cent.|
|“We have been able to achieve a record efficiency of 16.6 per cent for a semi-transparent perovskite cell, and 24.5 per cent for a perovskite-silicon tandem, which is one of the highest efficiencies reported for this type of cell,” said Dr White.|
|Dr White said the research placed ANU in a small group of labs around the world with the capability to improve silicon solar cell efficiency using perovskites.|
|The development builds on the state-of-the-art silicon cell research at ANU and is part of a $12.2 million “High-efficiency silicon/perovskite solar cells” project led by University of New South Wales and supported by $3.6 million of funding from the Australian Renewable Energy Agency.|
|Research partners include Monash University, Arizona State University, Suntech R&D Australia Pty Ltd and Trina Solar.|
|Source: The Australian National University|
21 Nov 2016
Quantum computing is heralded as the next revolution in terms of global computing. Google, Intel and IBM are just some of the big names investing millions currently in the field of quantum computing which will enable faster, more efficient computing required to power the requirements of our future computing needs.
|Now a researcher and his team at Tyndall National Institute in Cork have made a ‘quantum leap’ by developing a technical step that could enable the use of quantum computers sooner than expected.|
|Conventional digital computing uses ‘on-off’ switches, but quantum computing looks to harness quantum state of matters – such as entangled photons of light or multiple states of atoms – to encode information. In theory, this can lead to much faster and more powerful computer processing, but the technology to underpin quantum computing is currently difficult to develop at scale.|
|Researchers at Tyndall have taken a step forward by making quantum dot light-emitting diodes (LEDs) that can produce entangled photons (whose actions are linked), theoretically enabling their use to encode information in quantum computing.|
|This is not the first time that LEDs have been made that can produce entangled photons, but the methods and materials described in the new paper (Nature Photonics, “Selective carrier injection into patterned arrays of pyramidal quantum dots for entangled photon light-emitting diodes”) have important implications for the future of quantum technologies, explains researcher Dr Emanuele Pelucchi, Head of Epitaxy and Physics of Nanostructures and a member of the Science Foundation Ireland-funded Irish Photonic Integration Centre (IPIC) at Tyndall National Institute in Cork.|
|Dr Emanuele Pelucchi.|
|“The new development here is that we have engineered a scalable array of electrically driven quantum dots using easily-sourced materials and conventional semiconductor fabrication technologies, and our method allows you to direct the position of these sources of entangled photons,” he says.|
|“Being able to control the positions of the quantum dots and to build them at scale are key factors to underpin more widespread use of quantum computing technologies as they develop.”|
|The Tyndall technology uses nanotechnology to electrify arrays of the pyramid-shaped quantum dots so they produce entangled photons. “We exploit intrinsic nanoscale properties of the whole “pyramidal” structure, in particular, an engineered self-assembled vertical quantum wire, which selectively injects current into the vicinity of a quantum dot,” explains Dr Pelucchi.|
|“The reported results are an important step towards the realization of integrated quantum photonic circuits designed for quantum information processing tasks, where thousands or more sources would function in unison.”|
|“It is exciting to see how research at Tyndall continues to break new ground, particularly in relation to this development in quantum computing. The significant breakthrough by Dr Pelucchi advances our understanding of how to harness the opportunity and power of quantum computing and undoubtedly accelerates progress in this field internationally. Photonics innovations by the IPIC team at Tyndall are being commercialized across a number sectors and as a result, we are directly driving global innovation through our investment, talent and research in this area,” said Dr Kieran Drain, CEO at Tyndall National Institute.|
|Source: Tyndall National Institute|
14 Oct 2016
Recently, researchers at the National Renewable Energy Laboratory wanted to know, how well does NREL’s hydrogen infrastructure support fueling multiple fuel cell electric vehicles (FCEVs) for a day trip to the Rocky Mountains?
The answer-great! NREL staff took FCEVs on a trip to demonstrate real-world performance and range in high-altitude conditions. To start the trip, drivers filled three cars at NREL’s hydrogen fueling station. The cars made a 175-mile loop crossing two 11,000+ foot mountain passes on the way. Back at NREL, the cars were filled up with hydrogen in ~5 minutes and ready to go again. Learn more at http://www.nrel.gov/hydrogen.
Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”
Read More on Nano Enabled Fuel Cell Technologies for many more Energy Applications: Genesis Nanotechnology Fuel Cell Articles & Videos
07 Oct 2016
** Special to the Washington Post
The batteries that power our high-tech lifestyle are built using materials extracted in dirty, often life-threatening conditions.
If you have a cell phone, laptop, a hybrid car, or an electric vehicle, you may want to sit down. This may hurt.
You have probably heard of blood diamonds and conflict minerals. Maybe you’ve even read up a bit on how big consumer tech companies are trying (and, in some cases, being forced by governments) to sort out where the materials that go into their gadgets come from. But stories about “supply chains,” “globalization,” and “poor working conditions” can seem a world away, or just plain academic.
In a sweeping, heartbreaking series, the Washington Post is making sure it hits home.
Take the example of Yu Yuan, a farmer who lives near a graphite factory in northeastern China. In a video, he swipes at shimmering grime accumulated in his window sill and points at a barren cornfield.
The crops turn black with graphite dust he says, and don’t grow properly. He and his wife worry about the air they’re breathing and their water is undrinkable, polluted by chemicals dumped from the graphite plant. “There is nothing here once the factory is done damaging this place,” he says.
Workers in Lubumbashi, Democratic Republic of the Congo, tend to an oven that processes slag from the region’s cobalt and copper-rich ores.
Over two pieces so far, the Post has traced the path of first cobalt and then graphite as they make their way from mines to factories and ultimately into our hands as the cathodes and anodes, respectively, for lithium-ion batteries.
Each story is a remarkable blend of globe-spanning investigative journalism, business reporting, and an appeal to us to confront the consequences of owning the devices that power our high-tech lifestyles.
While graphite is mined and processed mostly in China, a huge amount of cobalt comes from mines in the Democratic Republic of the Congo, where “artisanal” miners sometimes dig through the floor of their own houses in search of ore. Mines collapse frequently. Injuries and death are commonplace.
Once extracted, the materials end up in Asia, where companies you’ve probably never heard of turn them into battery parts. The largest battery makers in the world, including Samsung SDI, LG Chem, and Panasonic, then purchase the components and turn them into batteries that go into phones, computers, and cars. (article continued below)
A “New Way” to Power Our World?
Read (Watch the YouTube Video Below) About a New Energy Storage Company ~ Making Energy Dense, Flexible Form, Rapid Charge/ Re-Charge Super Capacitors and Batteries for Medical Devices, Drone Batteries, Power Banks, Motorcycle and EV Batteries, developed from a Rice University Technology using ‘Nanoporous Nickle’ and ‘Si Nano Wires.
(article continued) Lithium batteries are prized for being light and having a high energy density compared to other battery chemistries. The modern smartphone would be difficult to imagine without a lithium battery as its power supply. They help power hybrid cars, and the small but fast-growing fleet of all-electric vehicles wouldn’t exist without them.
Interest in electric cars, in particular, is fueled by claims that the vehicles are clean and good for the environment. That may be true in the countries where they are mostly sold. But when we consider the bigger picture, the reality is something else altogether.
Read More: MIT Review – August 2016
Startups with novel chemistries tend to falter before they reach full production.
Earlier this year, Ellen Williams, the director of ARPA-E, the U.S. Department of Energy’s advanced research program for alternative energy, made headlines when she told the Guardiannewspaper that “We have reached some holy grails in batteries.”
Despite very promising results from the 75-odd energy-storage research projects that ARPA-E funds, however, the grail of compact, low-cost energy storage remains elusive.
A number of startups are closer to producing devices that are economical, safe, compact, and energy-dense enough to store energy at a cost of less than $100 a kilowatt-hour. Energy storage at that price would have a galvanic effect, overcoming the problem of powering a 24/7 grid with renewable energy that’s available only when the wind blows or the sun shines, and making electric vehicles lighter and less expensive.
But those batteries are not being commercialized at anywhere near the pace needed to hasten the shift from fossil fuels to renewables. Even Tesla CEO Elon Musk, hardly one to underplay the promise of new technology, has been forced to admit that, for now, the electric-car maker is engaged in a gradual slog of enhancements to its existing lithium-ion batteries, not a big leap forward.
In fact, many researchers believe energy storage will have to take an entirely new chemistry and new physical form, beyond the lithium-ion batteries that over the last decade have shoved aside competing technologies in consumer electronics, electric vehicles, and grid-scale storage systems. In May the DOE held a symposium entitled “Beyond Lithium-Ion.” The fact that it was the ninth annual edition of the event underscored the technological challenges of making that step.
Qichao Hu, the founder of SolidEnergy Systems, has developed a lithium-metal battery (which has a metallic anode, rather than the graphite material used for the anode in traditional lithium-ion batteries) that offers dramatically improved energy density over today’s devices (see“Better Lithium Batteries to Get a Test Flight”). The decade-long process of developing the new system highlighted one of the main hurdles in battery advancement: “In terms of moving from an idea to a product,” says Hu, “it’s hard for batteries, because when you improve one aspect, you compromise other aspects.”
Added to this is the fact that energy storage research has a multiplicity problem: there are so many technologies, from foam batteries to flow batteries to exotic chemistries, that no one clear winner is attracting most of the funding and research activity.
According to a recent analysis of more than $4 billion in investments in energy storage by Lux Research, startups developing “next-generation” batteries—i.e., beyond lithium-ion—averaged just $40 million in funding over eight years. Tesla’s investment in its Gigafactory, which will produce lithium-ion batteries, will total around $5 billion. That huge investment gap is hard to overcome.
“It will cost you $500 million to set up a small manufacturing line and do all the minutiae of research you need to do to make the product,” says Gerd Ceder, a professor of materials science at the University of California, Berkeley, who heads a research group investigating novel battery chemistries. Automakers, he points out, may test new battery systems for years before making a purchase decision. It’s hard to invest $500 million in manufacturing when your company has $5 million in funding a year.
Even if new battery makers manage to bring novel technologies to market, they face a dangerous period of ramping up production and finding buyers. Both Leyden Energy and A123 Systems failed after developing promising new systems, as their cash needs climbed and demand failed to meet expectations. Two other startups, Seeo and Sakti3, were acquired before they reached mass production and significant revenues, for prices below what their early-stage investors probably expected.
Meanwhile, the Big Three battery producers, Samsung, LG, and Panasonic, are less interested in new chemistries and radical departures in battery technology than they are in gradual improvements to their existing products. And innovative battery startups face one major problem they don’t like to mention: lithium-ion batteries, first developed in the late 1970s, keep getting better.
Read more: Why We Still Don’t Have Better Batteries The Washington Post
Genesis Nanotechnology, Inc.
Follow and ‘Like’ Us on Facebook: https://www.facebook.com/GenesisNanoTech/
Follow Us On Twitter: https://twitter.com/GenesisNanoTech
“Join the Conversation” on Our LinkedIn ‘Nano Network’ Group:https://www.linkedin.com/groups/3935461
Connect To Our Website: http://genesisnanotech.com/
Watch Our YouTube Video: https://youtu.be/Y1618kgUSXI
Follow Our ‘Top Ten’ Blog: “Great Things from Small Things”: https://genesisnanotech.wordpress.com/
Contact with Your Comments – We Love Hearing from You!
Credit: American Chemical Society
Batteries in smart phones and other portable electronics often die at inopportune times. Carrying a spare battery is one solution. As an alternative, researchers have tried to create fibers to incorporate in clothing that would power these devices. However, many of these fibers can’t withstand clothing manufacturing, especially weaving and cutting.
Now, in the journal ACS Nano, scientists report the first fibers suitable for weaving into tailorable textiles that can capture and release solar energy.
To collect solar power, Wenjie Mai, Xing Fan and colleagues created two different types of fibers. One contained titanium or a manganese-coated polymer along with zinc oxide, a dye and an electrolyte. These fibers were then interlaced with copper-coated polymer wires to create the solar cell section of the textile. To store power, the researchers developed a second type of fiber. This one was made of titanium, titanium nitride, a thin carbon shell to prevent oxidation and an electrolyte. These fibers were woven with cotton yarn.
When combined, the new materials formed a flexible textile that the team could cut and tailor into a “smart garment” that was fully charged by sunlight. The researchers say the clothing could potentially power small electronics including tablets and phones.(Article Continues Below – After Tenka Energy Story)
Read About (Watch the YouTube Video)
Tenka Energy, LLC is developing and commercializing the Next Generation of Super-Capacitors andBatteries, providing the High-Energy-Density,in Flexible-Thin-Form with Rapid Charge/ Recharge Cycles with Extended Life that is required and in high demand from a“power starved world”. The opportunity is based on a Nanoporous-Nickel Flexible Thin-form technology that is easily scaled, from Rice University. Applications: Powered Smart Cards, Wearable Electronics, Drone Batteries, Medical Devices, Motorcycle and EV Batteries – just to name a few!
(Article Continued) Explore further: New fabric uses sun and wind to power devices
More information: Zhisheng Chai et al. Tailorable and Wearable Textile Devices for Solar Energy Harvesting and Simultaneous Storage, ACS Nano(2016). DOI: 10.1021/acsnano.6b05293
The pursuit of harmonic combination of technology and fashion intrinsically points to the development of smart garments. Herein, we present an all-solid tailorable energy textile possessing integrated function of simultaneous solar energy harvesting and storage, and we call it tailorable textile device. Our technique makes it possible to tailor the multifunctional textile into any designed shape without impairing its performance and produce stylish smart energy garments for wearable self-powering system with enhanced user experience and more room for fashion design.
The “threads” (fiber electrodes) featuring tailorability and knittability can be large-scale fabricated and then woven into energy textiles. The fiber supercapacitor with merits of tailorability, ultrafast charging capability, and ultrahigh bending-resistance is used as the energy storage module, while an all-solid dye-sensitized solar cell textile is used as the solar energy harvesting module. Our textile sample can be fully charged to 1.2 V in 17 s by self-harvesting solar energy and fully discharged in 78 s at a discharge current density of 0.1 mA.
Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”
07 Oct 2016
Equipment at a brewery. Credit: FTGallo / Wikipedia.
University of Colorado Boulder engineers have developed an innovative bio-manufacturing process that uses a biological organism cultivated in brewery wastewater to create the carbon-based materials needed to make energy storage cells.
This unique pairing of breweries and batteries could set up a win-win opportunity by reducing expensive wastewater treatment costs for beer makers while providing manufacturers with a more cost-effective means of creating renewable, naturally-derived fuel cell technologies.
“Breweries use about seven barrels of water for every barrel of beer produced,” said Tyler Huggins, a graduate student in CU Boulder’s Department of Civil, Environmental and Architectural Engineering and lead author of the new study. “And they can’t just dump it into the sewer because it requires extra filtration.”
The process of converting biological materials, or biomass, such as timber into carbon-based battery electrodes is currently used in some energy industry sectors. But, naturally-occurring biomass is inherently limited by its short supply, impact during extraction and intrinsic chemical makeup, rendering it expensive and difficult to optimize.
However, the CU Boulder researchers utilize the unsurpassed efficiency of biological systems to produce sophisticated structures and unique chemistries by cultivating a fast-growing fungus, Neurospora crassa, in the sugar-rich wastewater produced by a similarly fast-growing Colorado industry: breweries.
“The wastewater is ideal for our fungus to flourish in, so we are happy to take it,” said Huggins.
By cultivating their feedstock in wastewater, the researchers were able to better dictate the fungus’s chemical and physical processes from the start. They thereby created one of the most efficient naturally-derived lithium-ion battery electrodes known to date while cleaning the wastewater in the process.
The findings were published recently in the American Chemical Society journal Applied Materials & Interfaces.
If the process were applied on a large scale, breweries could potentially reduce their municipal wastewater costs significantly while manufacturers would gain access to a cost-effective incubating medium for advanced battery technology components.
“The novelty of our process is changing the manufacturing process from top-down to bottom-up,” said Zhiyong Jason Ren, an associate professor in CU Boulder’s Department of Civil, Environmental and Architectural Engineering and a co-author of the new study. “We’re biodesigning the materials right from the start.”
Huggins and study co-author Justin Whiteley, also of CU Boulder, have filed a patent on the process and created Emergy, a Boulder-based company aimed at commercializing the technology.
“We see large potential for scaling because there’s nothing required in this process that isn’t already available,” said Huggins.
The researchers have partnered with Avery Brewing in Boulder in order to explore a larger pilot program for the technology. Huggins and Whiteley recently competed in the finals of a U.S. Department of Energy-sponsored startup incubator competition at the Argonne National Laboratory in Chicago, Illinois.
“This research speaks to the spirit of entrepreneurship at CU Boulder,” said Ren, who plans to continue experimenting with the mechanisms and properties of the fungus growth within the wastewater. “It’s great to see students succeeding and creating what has the potential to be a transformative technology. Energy storage represents a big opportunity for the state of Colorado and beyond.”
Explore further: Researchers use wastewater treatment to capture CO2, produce energy
More information: Tyler M. Huggins et al. Controlled Growth of Nanostructured Biotemplates with Cobalt and Nitrogen Codoping as a Binderless Lithium-Ion Battery Anode, ACS Applied Materials & Interfaces (2016). DOI: 10.1021/acsami.6b09300
07 Oct 2016
Oil and gas operations in the United States produce about 21 billion barrels of wastewater per year. The saltiness of the water and the organic contaminants it contains have traditionally made treatment difficult and expensive.
Engineers at the University of Colorado Boulder have invented a simpler process that can simultaneously remove both salts and organic contaminants from the wastewater, all while producing additional energy. The new technique, which relies on a microbe-powered battery, was recently published in thejournal Environmental Science Water Research & Technology as the cover story.
“The beauty of the technology is that it tackles two different problems in one single system,” said Zhiyong Jason Ren, a CU-Boulder associate professor of environmental and sustainability engineering and senior author of the paper. “The problems become mutually beneficial in our system—they complement each other—and the process produces energy rather than just consumes it.”
The new treatment technology, called microbial capacitive desalination, is like a battery in its basic form, said Casey Forrestal, a CU-Boulder postdoctoral researcher who is the lead author of the paper and working to commercialize the technology. “Instead of the traditional battery, which uses chemicals to generate the electrical current, we use microbes to generate an electrical current that can then be used for desalination.”
This microbial electro-chemical approach takes advantage of the fact that the contaminants found in the wastewater contain energy-rich hydrocarbons, the same compounds that make up oil andnatural gas. The microbes used in the treatment process eat the hydrocarbons and release their embedded energy. The energy is then used to create a positively charged electrode on one side of the cell and a negatively charged electrode on the other, essentially setting up a battery.
Because salt dissolves into positively and negatively charged ions in water, the cell is then able to remove the salt in the wastewater by attracting the charged ions onto the high-surface-area electrodes, where they adhere.
Not only does the system allow the salt to be removed from the wastewater, but it also creates additional energy that could be used on site to run equipment, the researchers said.
“Right now oil and gas companies have to spend energy to treat the wastewater,” Ren said. “We are able to treat it without energy consumption; rather we extract energy out of it.”
Some oil and gas wastewater is currently being treated and reused in the field, but that treatment process typically requires multiple steps—sometimes up to a dozen—and an input of energy that may come from diesel generators.
Because of the difficulty and expense, wastewater is often disposed of by injecting it deep underground. The need to dispose of wastewater has increased in recent years as the practice of hydraulic fracturing, or “fracking,” has boomed. Fracking refers to the process of injecting a slurry of water, sand and chemicals into wells to increase the amount of oil and natural gas produced by the well.
Injection wells that handle wastewater from fracking operations can cause earthquakes in the region, according to past research by CU-Boulder scientists and others.
The demand for water for fracking operations also has caused concern among people worried about scarce water resources, especially in arid regions of the country. Finding water to buy for fracking operations in the West, for example, has become increasingly challenging and expensive for oil and gas companies.
Ren and Forrestal’s microbial capacitive desalination cell offers the possibility that water could be more economically treated on site and reused for fracking.
To try to turn the technology into a commercial reality, Ren and Forrestal have co-founded a startup company called BioElectric Inc. In order to determine if the technology offers a viable solution for oil and gas companies, the pair first has to show they can scale up the work they’ve been doing in the lab to a size that would be useful in the field.
The cost to scale up the technology also needs to be competitive with what oil and gas companies are paying now to buy water to use for fracking, Forrestal said. There also is some movement in state legislatures to require oil and gas companies to reuse wastewater, which could make BioElectric’s product more appealing even at a higher price, the researchers said.
MIT spinout makes treating, recycling highly contaminated oilfield water more economical
Explore further: New contaminants found in oil and gas wastewater
More information: “Microbial capacitive desalination for integrated organic matter and salt removal and energy production from unconventional natural gas produced water.” Environ. Sci.: Water Res. Technol., 2015,1, 47-55 DOI: 10.1039/C4EW00050A
Genesis Nanotechnology ~ “Great Things from Small Things”
YouTube Video: Genesis Nanotechnology Nano Enabled Water Treatment; Quantum Dots from Coal & More
24 Sep 2016
“I try to guide my research by … asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’” says Rohit Karnik, an associate professor in MIT’s Department of Mechanical Engineering. Photo: Ken Richardson
Engineer’s designs may help purify water, diagnose disease in remote regions of world.
In Rohit Karnik’s lab, researchers are searching for tiny solutions to some of the world’s biggest challenges.
In one of his many projects, Karnik, an associate professor in MIT’s Department of Mechanical Engineering, is developing a new microfluidic technology that can quickly and simply sorts cells from small samples of blood. The surface of a microfluidic channel is patterned to direct certain cells to roll toward a reservoir for further analysis, while allowing the rest of the blood sample to pass through. With this design, Karnik envisions developing portable, disposable devices that doctors may use, even in remote regions of the world, to quickly diagnose conditions ranging from malaria to sepsis.
Karnik’s group is also tackling issues of water purification. The researchers are designing filters from single layers of graphene, which are atom-thin sheets of carbon known for their exceptional strength. Karnik has devised a way to control the size and concentration of pores in graphene, and is tailoring single layers to filter out miniscule and otherwise evasive contaminants. The group has also successfully filtered salts using the technique and hopes to develop efficient graphene filters for water purification and other applications.
In looking for water-purifying solutions, Karnik’s group also identified a surprisingly low-tech option: the simple tree branch. Karnik found that the pores within a pine branch that normally help to transport water up the plant are ideal for filtering bacteria from water. The group has shown that a peeled pine branch can filter out up to 99.00 percent of E. coli from contaminated water. Karnik’s group is building up on this work to explore the potential for simple and affordable wood-based water purification systems. (continued below)
These Are the World’s Most ‘Sustainable’ Cities [From the World Economic Forum]
What does it mean to be a ‘sustainable city’, and which cities around the world are best at it? A new index sets out to find the most successful from a list of 100 cities.
The ranking from Arcadis, a design and consultancy firm, and the Centre for Economic and Business Research, assesses the sustainability of cities based on three dimensions. The ranking also highlights the pressure cities are under – from population growth to natural disasters.
“Balancing the immediate needs of today without compromising the needs of tomorrow is at the heart of being a sustainable city,” the authors write.
(continued from above) “I try to guide my research by long-term sustainability, in a specific sense, by asking myself the question, ‘What can we do today that will have a lasting impact and be conducive to a sustainable human civilization?’ Karnik says. “I try to align myself with that goal.”
From stargazer to tinkerer
Karnik was born and raised in Pune, India, which was then a relatively quiet city 100 miles east of Mumbai. Karnik describes himself while growing up as shy, yet curious about the way the world worked. He would often set up simple experiments in his backyard, seeing, for instance, how transplanting ants from one colony to another would change the ants’ behavior. (The short answer: They fought, sometimes to the death.) He developed an interest in astronomy early on and often explored the night sky with a small telescope, from the roof of his family’s home.
“I used to take my telescope up to the terrace in the middle of the night, which required three different trips up six or seven flights of stairs,” Karnik says. “I’d set the alarm for 3 a.m., go up, and do quite a bit of stargazing.”
That telescope would soon serve another use, as Karnik eventually found that, by inverting it and adding another lens, he could repurpose the telescope as a microscope.
“I built a little setup so I could look at different things, and I used to collect stuff from around the house, like onion peels or fungus growing on trees, to look at their cells,” Karnik says.
When it came time to decide on a path of study, Karnik was inspired by his uncle, a mechanical engineer who built custom machines “that did all kinds of things, from making concrete bricks, to winding up springs,” Karnik says. “What I saw in mechanical engineering was the ability to building something that integrates across different disciplines.”
Seeking balance and insight
As an entering student at the Indian Institute of Technology Bombay, Karnik chose to study mechanical engineering over electrical engineering, which was the more popular choice among students at the time. For his thesis, he looked for new ways to model three-dimensional cracks in materials such as steel beams.
Casting around for a direction after graduating, Karnik landed on the fast-growing field of nanotechnology. Arun Majumdar, an IIT alum and professor at the University of California at Berkeley, was studying energy conversion and biosensing in nanoscale systems. Karnik joined the professor’s lab as a graduate student, moving to California in 2002. For his graduate work, Karnik helped to develop a microfluidic platform to rapidly mix the contents of and test reactions occurring within droplets. He followed this work up with a PhD thesis in which he explored how fluid, flowing through tiny, nanometer-sized channels, can be controlled to sense and direct ions and molecules.
Toward the end of his graduate work, Karnik interviewed for and ultimately accepted a faculty position at MIT. However, he was still completing his PhD thesis at Berkeley and had less than 4 years of experience beyond his bachelor’s degree. To help ease the transition, MIT offered Karnik an interim postdoc position in the lab of Robert Langer, the David H. Koch Institute Professor and a member of the Koch Institute for Integrative Cancer Research.
“It was an insightful experience,” Karnik remembers. “For a mechanical engineer who’s never been outside mechanical engineering, I basically had little experience how to do things in biology. It opened up possibilities for working with the biomedical community.”
When Karnik finally assumed his position as assistant professor of mechanical engineering in 2007, he experienced a tidal wave of deadlines, demands, and responsibilities — a common initiation for first-time faculty.
“By its nature the job is overwhelming,” Karnik says. “The trick is how to maintain balance and sanity and do the things you like, without being distracted by the busyness around you, in some sense.”
He says several things have helped him to handle and even do away with stress: walks, which he takes each day to work and around campus, as well as yoga and meditation.
“If you can see things the way they are, by clearing away the filters your mind puts in place, you can get a clear perspective, and there are a lot of insights that come through,” Karnik says.
24 Sep 2016
In a discovery that could have profound implications for future energy policy, Columbia scientists have demonstrated it is possible to manufacture solar cells that are far more efficient than existing silicon energy cells by using a new kind of material, a development that could help reduce fossil fuel consumption.
The team, led by Xiaoyang Zhu, a professor of Chemistry at Columbia University, focused its efforts on a new class of solar cell ingredients known as Hybrid Organic Inorganic Perovskites (HOIPs).
Their results, reported in the prestigious journal Science, also explain why these new materials are so much more efficient than traditional solar cells—solving a mystery that will likely prompt scientists and engineers to begin inventing new solar materials with similar properties in the years ahead.
“The need for renewable energy has motivated extensive research into solar cell technologies that are economically competitive with burning fossil fuel,” Zhu says.
“Among the materials being explored for next generation solar cells, HOIPs have emerged a superstar. Until now no one has been able to explain why they work so well, and how much better we might make them. We now know it’s possible to make HOIP-based solar cells even more efficient than anyone thought possible.”
Solar cells are what turn sunlight into electricity. Also known as photovoltaic cells, these semiconductors are most frequently made from thin layers of silicon that transmit energy across its structure, turning it into DC current.
Silicon panels, which currently dominate the market for solar panels, must have a purity of 99.999 percent and are notoriously fragile and expensive to manufacture. Even a microscopic defect—such as misplaced, missing or extra ions—in this crystalline structure can exert a powerful pull on the charges the cells generate when they absorb sunlight, dissipating those charges before they can be transformed into electrical current.
In 2009, Japanese scientists demonstrated it was possible to build solar cells out of HOIPs, and that these cells could harvest energy from sunlight even when the crystals had a significant number of defects. Because they don’t need to be pristine, HOIPs can be produced on a large scale and at low cost. The Columbia team has been investigating HOIPs since 2014. Their findings could help boost the use of solar power, a priority in the age of global warming.
Over the last seven years, scientists have managed to increase the efficiency with which HOIPs can convert solar energy into electricity, to 22 percent from 4 percent. By contrast, it took researchers more than six decades to create silicon cells and bring them to their current level, and even now silicon cells can convert no more than about 25 percent of the sun’s energy into electrical current.
This discovery, Zhu said, meant that “scientists have only just begun to tap the potential of HOIPs to convert the sun’s energy into electricity.”
Theorists long ago demonstrated that the maximum efficiency silicon solar cells might ever reach— the percentage of energy in sunlight that might be converted to electricity we can use—is roughly 33 percent. It takes hundreds of nanoseconds for energized electrons to move from the part of a solar cell that infuses them with the sun’s energy, to the part of the cell that harvests the energy and converts it into electricity that can ultimately be fed into a power grid. During this migration across the solar cell, the energized electrons quickly dissipate their excess energy.
But those calculations assume a specific rate of energy loss.
The Columbia team discovered that the rate of energy loss is slowed down by over three-orders of magnitude in HOIPs – making it possible for the harvesting of excess electronic energy to increase the efficiency of solar cells.
“We’re talking about potentially doubling the efficiency of solar cells,” says Prakriti P. Joshi, a Ph.D. student in Zhu’s lab who is a coauthor on the paper. “That’s really exciting because it opens up a big, big field in engineering.” Adds Zhu, “This shows we can push the efficiencies of solar cells much higher than many people thought possible.”
After demonstrating this, the team then turned to the next question: what is it about the molecular structure of HOIPs that gives them their unique properties? How do electrons avoid defects? They discovered that the same mechanism that slows down the cooling of electron energy also protects the electrons from bumping into defects.
This “protection” makes the HOIPs turn a blind eye to the ubiquitous defects in a material developed from room-temperature and solution processing, thus allowing an imperfect material to behave like a perfect semiconductor.
HOIPs contain lead, and are also water soluble, meaning the solar cells could begin to dissolve and leach lead into the environment around them if not carefully protected from the elements.
With the explanation of the mysterious mechanisms that give HOIPs their remarkable efficiencies, Zhu knew, material scientists would likely be able to mimic them with more environmentally-friendly materials.
“Now we can go back and design materials which are environmentally benign and really solve this problem everybody is worried about,” Zhu says. “This principle will allow people to start to design new materials for solar energy.”
Explore further: New plastic solar cell minimizes loss of photon energy
More information: H. Zhu et al. Screening in crystalline liquids protects energetic carriers in hybrid perovskites, Science (2016). DOI: 10.1126/science.aaf9570
Journal reference: Science
Provided by: Columbia University