#Steam from the sun A new material structure developed at MIT generates steam by soaking up the sun. The structure a layer of graphite flakes
and an underlying carbon foam is a porous, insulating material structure that floats on water. When sunlight hits the structure surface, it creates a hotspot in the graphite,
drawing water up through the material pores, where it evaporates as steam. The brighter the light, the more steam is generated.
The new material is able to convert 85 percent of incoming solar energy into steam a significant improvement over recent approaches to solar-powered steam generation.
What more the setup loses very little heat in the process, and can produce steam at relatively low solar intensity.
This would mean that, if scaled up, the setup would likely not require complex, costly systems to highly concentrate sunlight.
Hadi Ghasemi, a postdoc in MIT Department of Mechanical engineering, says the spongelike structure can be made from relatively inexpensive materials a particular advantage for a variety of compact,
steam-powered applications. team is important for desalination, hygiene systems, and sterilization, says Ghasemi, who led the development of the structure. specially in remote areas where the sun is the only source of energy,
if you can generate steam with solar energy, it would be very useful. Ghasemi and mechanical engineering department head Gang Chen,
along with five others at MIT, report on the details of the new steam-generating structure in the journal Nature Communications.
Recently, scientists have explored ways to improve the efficiency of solar-thermal harvesting by developing new solar receivers and by working with nanofluids.
The latter approach involves mixing water with nanoparticles that heat up quickly when exposed to sunlight, vaporizing the surrounding water molecules as steam.
Its top layer is made from graphite that the researchers exfoliated by placing the material in a microwave.
is ust like popcorn The graphite bubbles up, forming a nest of flakes. The result is a highly porous material that can better absorb
As sunlight hits the structure, it creates a hotspot in the graphite layer, generating a pressure gradient that draws water up through the carbon foam.
As water seeps into the graphite layer, the heat concentrated in the graphite turns the water into steam.
The structure works much like a sponge that, when placed in water on a hot,
sunny day, can continuously absorb and evaporate liquid. The researchers tested the structure by placing it in a chamber of water
The device worn around one s wrist works essentially like two extra fingers adjacent to the pinky and thumb.
A novel control algorithm enables it to move in sync with the wearer s fingers to grasp objects of various shapes and sizes.
Wearing the robot a user could use one hand to for instance hold the base of a bottle while twisting off its cap.
This is a completely intuitive and natural way to move your robotic fingers says Harry Asada the Ford Professor of Engineering in MIT s Department of Mechanical engineering.
Ultimately Asada says with some training people may come to perceive the robotic fingers as part of their body like a tool you have been using for a long time you feel the robot as an extension of your hand.
He and graduate student Faye Wu presented a paper on the robot this week at the Robotics:
Science and Systems conference in Berkeley Calif. Biomechanical synergythe robot which the researchers have dubbed supernumerary robotic fingers consists of actuators linked together to exert forces as strong as those of human fingers during a grasping motion.
To develop an algorithm to coordinate the robotic fingers with a human hand the researchers first looked to the physiology of hand gestures learning that a hand s five fingers are highly coordinated.
The researchers hypothesized that a similar biomechanical synergy may exist not only among the five human fingers but also among seven.
To test the hypothesis Wu wore a glove outfitted with multiple position-recording sensors and attached to her wrist via a light brace.
and robotic joint angles multiple times with various objects then analyzed the data and found that every grasp could be explained by a combination of two or three general patterns among all seven fingers.
The researchers used this information to develop a control algorithm to correlate the postures of the two robotic fingers with those of the five human fingers.
Asada explains that the algorithm essentially teaches the robot to assume a certain posture that the human expects the robot to take.
As a user works with the robot it could learn to adapt to match his
She likens this machine learning to that of voice-command systems like Apple s Siri. After you ve been using it for a while it gets used to your pronunciation so it can tune to your particular accent Wu says.
and robots interact says Matthew Mason director of the Robotics Institute at Carnegie mellon University who was involved not in the research.
when water droplets spontaneously jump away from superhydrophobic surfaces during condensation they can gain electric charge in the process.
Now the same team has demonstrated that this process can generate small amounts of electricity that might be used to power electronic devices.
The new findings by postdoc Nenad Miljkovic associate professor of mechanical engineering Evelyn Wang and two others are published in the journal Applied Physics Letters.
This approach could lead to devices to charge cellphones or other electronics using just the humidity in the air.
As a side benefit the system could also produce clean water. The device itself could be simple Miljkovic says consisting of a series of interleaved flat metal plates.
Although his initial tests involved copper plates he says any conductive metal would do including cheaper aluminum.
or other sources of ambient energy and represents an amount that could be sufficient to provide useful power for electronic devices in some remote locations.
For example Miljkovic has calculated that at 1 microwatt per square centimeter a cube measuring about 50 centimeters on a side about the size of a typical camping cooler could be sufficient to fully charge a cellphone in about 12 hours.
Because the process relies on condensation it requires a humid environment as well as a source of temperatures colder than the surrounding air such as a cave or river.
and Wang s 2013 finding in attempting to develop an improved heat-transfer surface to be used as a condenser in applications such as power plants that droplets on a superhydrophobic surface convert surface energy to kinetic energy as they merge to form larger droplets.
They later found that in that process the jumping droplets gain a small electric charge meaning that the jumping
For powering remote automated environmental sensors even a tiny amount of energy might be sufficient;
Chuanhua Duan an assistant professor of mechanical engineering at Boston University who was involved not in this research says This work provides a new approach for energy harvesting
which can be used to power microelectromechanical devices and small electronic devices. He adds Getting power from a condensation process is definitely a novel idea as condensation is used mainly for thermal management.#
and anti-icing but no one has correlated condensation with energy harvesting before. The research which also included MIT graduate student Daniel Preston and former postdoc Ryan Enright now at Lucent Ireland Ltd. was supported by MIT s Solid-state Solar-Thermal energy Conversion Center
(S3tec) funded by the U s. Department of energy; the Office of Naval Research; and the National Science Foundation n
and inventor Nikola Tesla proposed a global system of wireless transmission of electricity or wireless power.
Near the end of the last decade however a team of MIT researchers led by Professor of Physics Marin Soljacic took definitive steps toward more practical wireless charging.
First in 2007 the team wirelessly lit a 60-watt light bulb from eight feet away using two large copper coils with similarly tuned resonant frequencies that transferred energy from one to the other over the magnetic field.
Now this wireless electricity (or Witricity) technology licensed through the researchers startup Witricity Corp.#is coming to mobile devices electric vehicles and potentially a host of other applications.
Primarily this means consumers need not carry wires and power bricks. But it could also lead to benefits such as smaller batteries and less hardware
which would lower costs for manufacturers and consumers. It s probably a dream of any professor at MIT to help change the world for a better place says Soljacic a Witricity cofounder who now serves on its board of directors.
We believe wireless charging has a potential to do that. He is not alone. Last month Witricity signed a licensing agreement with Intel to integrate Witricity technology into computing devices powered by Intel.
Back in December Toyota licensed Witricity technology for a future line of electric cars. Several more publicized
and unpublicized companies have joined recently in the licensing parade for this technology including Thoratec for their implantable ventricular assisting devices
and TDK for wireless electric vehicle-charging systems. There s even talk of a helmet powered wirelessly via backpack specifically for military applications.
At present Witricity technology#charges devices#at around 6 to 12 inches with roughly 95 percent efficiency#12 watts for mobile devices and up to 6. 6 kilowatts for cars.
But with growing research and development the company is increasing distance scale and efficiency. It s also developed repeaters:#
Witricity Corp. recently unveiled a design for a smartphone and wireless charger powered by its technology.
The charger can charge two phones simultaneously and can be placed on top of a table or mounted underneath a table or desk.
Courtesy of Witricity Corp. Full Screen The Witricity technology can charge an electric car with the vehicle parked about a foot above the transmitting pad.
Courtesy of Witricity Corp. Full Screen Stronger couplingsimilar wireless charging technologies have been around for some time. For instance traditional induction charging
which uses an electromagnetic field to transfer energy between two coils is used in transformers and wireless toothbrushes.
#These work well but only over very short distances so they re nearly touching Soljacic says.
Lasers can also move energy between two points such as two satellites. But this requires an uninterrupted continuous path between the transmitter and the receiver
which is obviously not ideal for consumer products Soljacic says. Witricity s system of transmitters and receivers with magnetic coils on the other hand efficiently transfers power over longer distances says CEO Alex Gruzen 84 SM 86.
It can also charge through materials such as wood or granite allow freedom to move the devices around
and charge several devices at once. To make the system more efficient Witricity tunes the coils to find a strong electromagnetic highly resonant coupling.
or a radio antenna tuning into a single station out of hundreds.##The concept took shape in early 2000s
when Soljacic awoke at 3 a m. to the beeping of his cell phone running out of battery life.
Frustrated and standing half awake he contemplated ways to harness power from all around to charge the phone.
At the time he was working on various photonics projects lasers solar cells and optical fiber that all involved a phenomenon called resonant coupling.
#A new category of magnetic resonanceseeing use for consumer devices Soljacic and a team of five MIT researchers including physics professors Peter Fisher
One transmitting coil was connected to an AC power supply while another connected to a 60-watt light bulb.
The transmitter emanated a magnetic field oscillating at megahertz frequencies which the receiver matched ensuring a strong coupling between the units
and weak interaction with the rest of the environment including nonmetallic materials and humans. In fact they demonstrated that they could light the bulb at roughly 45 percent efficiency with all six researchers standing in between the two coils.
Gruzen uses the following analogy: A room is packed with 100 wine glasses each filled with a different level of wine to ensure a different resonant frequency.
If an opera singer belts out a note inside that room the glass with the corresponding frequency accumulates enough energy to shatter
when adding more receiver coils power transfer efficiency climbs by more than 10 percent. In that experiment they used larger transmitting coils
Wireless charging: An expectationthese days Gruzen sees wireless charging as analogous to the evolution of a similar technology Wifi that he witnessed in the early 2000s as senior vice president of global notebook business at Hewlett packard.
At the time Wifi capabilities were implemented rarely into laptops; this didn t change#until companies began bringing Wireless internet access into hotel lobbies libraries airports and other public places.
Now having established a standard for wireless charging#of consumer devices with the A4wp (Alliance for Wireless Power) known as Rezence Witricity aims to be the driving force behind wireless charging.
Soon Gruzen says it will be an expectation much like Wifi. You can have a charging surface wherever you go from a kitchen counter to your workplace to airport lounge
and hotel lobbies he says. In this future you re not worried about carrying cords. Casual access to topping off power in your devices just becomes an expected thing.
This is where we re Going with an expected rise of wireless charging one promising future application Soljacic sees is in medical devices especially implanted ventricular assist devices (or heart pumps) that support blood flow.
Currently a patient who has experienced a heart attack or weakening of the heart has wires running from the implant to a charger
which means risk for infection. In our case a patient could lie on the bed
and while he or she is sleeping our technology could charge the device from a distance Soljacic says.
We expect to have much more of these embedded electronic devices in people over the next decade or so t
#Own your own data Cellphone metadata has been in the news quite a bit lately but the National security agency isn t the only organization that collects information about people s online behavior.
Newly downloaded cellphone apps routinely ask to access your location information your address book or other apps and of course websites like Amazon or Netflix track your browsing history in the interest of making personalized recommendations.
At the same time a host of recent studies have demonstrated that it s shockingly easy to identify unnamed individuals in supposedly anonymized data sets even ones containing millions of records.
So if we want the benefits of data mining like personalized recommendations or localized services how can we protect our privacy?
In the latest issue of PLOS One MIT researchers offer one possible answer. Their prototype system openpds short for personal data store stores data from your digital devices in a single location that you specify:
It could be encrypted an server in the cloud but it could also be a computer in a locked box under your desk.
Any cellphone app online service or big data research team that wants to use your data has to query your data store
which returns only as much information as is required. Sharing code not data The example I like to use is personalized music says Yves-Alexandre de Montjoye a graduate student in media arts and sciences and first author on the new paper.
Pandora for example comes down to this thing that they call the music genome which contains a summary of your musical tastes.
To recommend a song all you need is the last 10 songs you listened to just to make sure you don t keep recommending the same one again and this music genome.
You don t need the list of all the songs you ve been listening to. With openpds de Montjoye says You share code;
you don t share data. Instead of you sending data to Pandora for Pandora to define what your musical preferences are it s Pandora sending a piece of code to you for you to define your musical preferences
and send it back to them. De Montjoye is joined on the paper by his thesis advisor Alex Sandy Pentland the Toshiba Professor of Media Arts and Sciences;
Erez Shmueli a postdoc in Pentland s group; and Samuel Wang a software engineer at Foursquare who was a graduate student in the Department of Electrical engineering
and Computer science when the research was done. After an initial deployment involving 21 people who used openpds to regulate access to their medical records the researchers are now testing the system with several telecommunications companies in Italy and Denmark.
Although openpds can in principle run on any machine of the user s choosing in the trials data is being stored in the cloud.
Meaningful permissionsone of the benefits of openpds de Montjoye says is that it requires applications to specify what information they need
and how it will be used. Today he says when you install an application it tells you this application has access to your fine-grained GPS location
or it has access to your SD card. You as a user have absolutely no way of knowing what that means.
The permissions don t tell you anything. In fact applications frequently collect much more data than they really need.
Service providers and application developers don t always know in advance what data will prove most useful
so they store as much as they can against the possibility that they may want it later.
It could for instance turn out that for some music listeners album cover art turns out to be a better predictor of
what songs they ll like than anything captured by Pandora s music genome. Openpds preserves all that potentially useful data but in a repository controlled by the end user not the application developer or service provider.
A developer who discovers that a previously unused bit of information is useful must request access to it from the user.
If the request seems unnecessarily invasive the user can simply deny it. Of course a nefarious developer could try to game the system constructing requests that elicit more information than the user intends to disclose.
A navigation application might for instance be authorized to identify the subway stop or parking garage nearest the user.
But it shouldn t need both pieces of information at once and by requesting them it could infer more detailed location information than the user wishes to reveal.
Creating safeguards against such information leaks will have to be done on a case-by-case application-by-application basis de Montjoye acknowledges
and at least initially the full implications of some query combinations may not be obvious. But even if it s not 100 percent safe it s still a huge improvement over the current state he says.
If we manage to get people to have access to most of their data and if we can get the overall state of the art to move from anonymization to interactive systems that would be such a huge win.
Openpds is one of the key enabling technologies for the digital society because it allows users to control their data
and at the same time open up its potential both at the economic level and at the level of society says Dirk Helbing a professor of sociology at ETH Zurich.
I don t see another way of making big data compatible with constitutional rights and human rights s
and water Whenever there is a major spill of oil into water the two tend to mix into a suspension of tiny droplets called an emulsion that is extremely hard to separate and that can cause severe damage to ecosystems.
The process is described in the journal Scientific Reports by MIT professor Kripa Varanasi graduate student Brian Solomon and postdoc M. Nasim Hyder.
and water that s extracted is put in large tanks to allow separation by gravity; the oil gradually floats to the top where it can be skimmed off.
That works well when the oil and water are already large globs of stuff already partly separated Varanasi says.
The difficulty significantly increases for nanoemulsions where the drop sizes are below a micron. To break down those emulsions crews use de-emulsifiers
which can themselves be environmentally damaging. In the 2010 Deepwater horizon oil spill in the Gulf of mexico for example large amounts of dispersants and de-emulsifiers were dumped into the sea.
After a while the oil just disappeared Varanasi says but people know it s hidden in the water in these fine emulsions.
and more importantly not discharging the produced water into the environment. Tiny droplets of water colored blue are suspended in oil on top of a membrane developed by the MIT team.
The membranes combine a very thin layer of nanopores with a thicker layer of micropores to limit the passage of unwanted material
in order to block them Varanasi says which in the case of nanoemulsions leads to very small pores
an ingenious process that makes large holes on one side that penetrate most of the way through the material providing little resistance to flow as well as nanoscale holes on the other surface in contact with the emulsion to be separated.
The thin layer with nanoscale pores allows for separation and the thick layer with large pores provides mechanical support.
A polymer solution is poured onto a glass plate Hyder explains; this casting plate is immersed then in a nonsolvent bath to induce precipitation to form a film.
The technique creates a bilayered polymer phase: One layer is polymer-rich and one is not.
As they precipitate out the polymer-rich phase develops the smaller pores; the polymer-lean phase makes the larger ones.
Since the solutions form a single sheet of film there is no need for bonding layers together
which can result in a weaker filter. There is no separate layer it s completely integrated
As a final stage a different polymer is added to give the material including the lining of the pores surfaces that attract
Solomon performed experiments showing the effectiveness of the membranes in separating nanoemulsions while maintaining integrity at high pressure.
Anish Tuteja an assistant professor of materials science and engineering at the University of Michigan who was involved not in this research calls it a very interesting and innovative approach to fabricating membranes that can separate out nanoemulsions.
Oil-water nanoemulsions are ubiquitous in a number of industries and these membranes could enable rapid separation of those emulsions with high purity and efficiency.
which supported the research through the MIT Energy Initiative to further test the material l
#Noninvasive brain control Optogenetics, a technology that allows scientists to control brain activity by shining light on neurons,
relies on light-sensitive proteins that can suppress or stimulate electrical signals within cells. This technique requires a light source to be implanted in the brain,
This noninvasive approach could pave the way to using optogenetics in human patients to treat epilepsy and other neurological disorders,
Led by Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, the researchers described the protein in the June 29 issue of Nature Neuroscience.
Optogenetics, a technique developed over the past 15 years, has become a common laboratory tool for shutting off or stimulating specific types of neurons in the brain,
such as an optical fiber, into the brain to control the selected neurons. Such implants can be difficult to insert,
however, and can be incompatible with many kinds of experiments, such as studies of development, during
or of neurodegenerative disorders, during which the implant can interact with brain physiology. In addition, it is difficult to perform long-term studies of chronic diseases with these implants.
To find a better alternative, Boyden, graduate student Amy Chuong, and colleagues turned to the natural world.
Many microbes and other organisms use opsins to detect light and react to their environment.
Most of the natural opsins now used for optogenetics respond best to blue or green light.
Boyden team had identified previously two light-sensitive chloride ion pumps that respond to red light, which can penetrate deeper into living tissue.
However these molecules, found in the bacteria Haloarcula marismortui and Haloarcula vallismortis, did not induce a strong enough photocurrent an electric current in response to light to be useful in controlling neuron activity.
Chuong set out to improve the photocurrent by looking for relatives of these proteins and testing their electrical activity.
The result of this screen, Jaws, retained its red-light sensitivity but had a much stronger photocurrent enough to shut down neural activity. his exemplifies how the genomic diversity of the natural world can yield powerful reagents that can be of use in biology and neuroscience,
says Boyden, who is a member of MIT Media Lab and the Mcgovern Institute for Brain Research.
the researchers were able to shut down neuronal activity in the mouse brain with a light source outside the animal head.
A key advantage to this opsin is that it could enable optogenetic studies of animals with larger brains,
says Garret Stuber, an assistant professor of psychiatry and cell biology and physiology at the University of North carolina at Chapel hill. n animals with larger brains,
people have had difficulty getting behavior effects with optogenetics, and one possible reason is that not enough of the tissue is being inhibited,
Working with researchers at the Friedrich Miescher Institute for Biomedical Research in Switzerland, the MIT team also tested Jaws ability to restore the light sensitivity of retinal cells called cones.
In people with a disease called retinitis pigmentosa, cones slowly atrophy, eventually causing blindness. Friedrich Miescher Institute scientists Botond Roska and Volker Busskamp have shown previously that some vision can be restored in mice by engineering those cone cells to express light-sensitive proteins.
Roska and Busskamp tested the Jaws protein in the mouse retina and found that it more closely resembled the eye natural opsins
making it potentially more useful for treating retinitis pigmentosa. This type of noninvasive approach to optogenetics could also represent a step toward developing optogenetic treatments for diseases such as epilepsy,
which could be controlled by shutting off misfiring neurons that cause seizures, Boyden says. ince these molecules come from species other than humans,
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