DARPA Wants Soldiers To Control Machines With Their Minds


Future machines, including weapons, won’t need handheld controls.

The Department of Defense’s research and development wing, DARPA, is working on technology to read and write to the human brain.

The focus isn’t on mind control but rather machine control, allowing the human brain to directly send instructions to machines.

The goal of the process is to streamline thought control of machines to the point where humans could control them with a simple helmet or head-mounted device, making operating such systems easier. 

The brain makes physical events happen by turning thoughts into action, sending instructions through the nervous system to organs, limbs, and other parts of the body.

It effortlessly sends out a constant stream of commands to do everything from drive a car to make breakfast. To operate today’s machines, humans being need a middleman of sorts, a physical control system manipulated by hands, fingers, and feet. 

What if human beings could cut out the middleman, operating a machine simply by thinking at it? So DARPA is funding the Next Generation Nonsurgical Neurotechnology (N3) initiative. N3’s goal is to create a control system for machines—including weapons—that can directly interact with the human brain.

According to IEEE Spectrum, DARPA is experimenting with “magnetic fields, electric fields, acoustic fields (ultrasound) and light” as a means of controlling machines. 

The implications of such a technology are huge. Instead of designing complicated controls and control systems for every machine or weapon devised, engineers could instead just create a thought-operated control system.

Wearable technology becomes easier to operate as it doesn’t require a separate control system. This could also apply to notifications and data: as IEEE Spectrum points out, network administrators could feel intrusions into computer networks. DAPRA is, of course, an arm of the Pentagon, and a neurotechnological interface would almost certainly find its way into weapons. 

DARPA has awarded development contracts to six groups for amounts of up to $19.48 million each. Each group has one year to prove their ability to read and write to brain tissue with an 18-month animal testing period to follow. 

The next and final step of the N3 project will involve human trials. 

Source: IEEE Spectrum

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What’s Coming: DARPA is Eyeing a High-Tech Contact Lens Straight Out of ‘Mission: Impossible’


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The Defense Advanced Research Projects Agency (DARPA) is reportedly interested in a new wirelessly-connected contact lens recently unveiled in France, the latest in the agency’s ongoing search for small-scale technology to augment U.S. service members’ visual capabilities in the field.

Researchers at leading French engineering IMT Atlantique in mid-April announced “the first autonomous contact lens incorporating a flexible micro-battery,” a lightweight lens capable of not only providing augmented vision assistance to users but relaying visual information wirelessly — not unlike, say, the lens Jeremy Renner uses in Mission: Impossible – Ghost Protocol to scan a batch of nuclear codes: (Watch)

More importantly, the new lens can perform its functions without a bulky external power supply, capable of “continuously supply[ing] a light source such as a light-emitting diode (LED) for several hours,” according to the IMT Atlantique announcement.

“Storing energy on small scales is a real challenge,” said Thierry Djenizian, head of the Flexible Electronics Department at the Centre Microélectronique de Provence Georges Charpak and co-head of the p

The lens was primarily designed for medical and automotive applications, but according to French business magazine L’Usine Nouvelle (‘The New Factory’), the lens has garnered interest from both DARPA and Microsoft, which was recently contracted by the the U.S. Army to furnish soldiers with with its HoloLens augmented reality headset.

DARPA’s been on the hunt for a high-tech eyepiece more than a decade, and the agency has funded several similar projects in recent years.

In January 2012, DARPA announced that U.S.-based tech firm Innovega was developing “iOptiks” contact lenses designed to enhance normal vision by projecting digital images onto a standard pair of eyeglasses like a miniaturized heads-up display, “allow[ing] a wearer to view virtual and augmented reality images without the need for bulky apparatus,” as the agency put it.

Three years later, researchers at Switzerland’s École Polytechnique Fédérale de Lausanne (EPFL) unveiled a DARPA-funded contact lens that “magnifies objects at the wink of an eye,” The Guardian reported, although researchers concluded that the technology was better suited for age-related visual deterioration rather than battlefield applications.

“[DARPA researchers] were really interested in supervision, but the reality is more tame than that,” researcher Eric Tremblay told the American Association for the Advancement of Science at the time.

These past projects, like most other blue sky research projects pursued by the DARPA, have likely informed the Pentagon’s research and development of augmented reality tech that U.S. military planners have increasingly pursued in recent years. And the technology is only poised to improve: as Wired recently reported, big tech companies like Google, Sony, and Samsung are all pushing the envelope when it comes to consumer-marketxed augmented vision tech.

But when “smart” contact lenses will actually hit Pentagon armories, like most futuristic DARPA efforts, remains to be seen. In the meantime, it looks like U.S. service members in search of enhanced vision will have to stick to their “birth control glasses.”

This article by Jared Keller originally appeared at Task & Purpose. Follow Task & Purpose onTwitter. This article first appeared in 2019.

Making Solar Cells Obsolete with GIT’s Optical ‘Rectenna’ Technology ~ 40% to 90% Conversion Effciency: YouTube Video


Optical Rectenna download

Georgia Tech Professor of Mechanical Engineering, Dr. Bara Cola, shares how his childhood dreams of playing professional football turned into an exciting research career and important nanoengineering innovations. Dr. Cola’s breakthrough optical rectenna technology can be viewed here https://smartech.gatech.edu/handle/18….”

Watch the YouTube Video:

 

e9cf3-nanorectannaA new kind of nanoscale rectenna (half antenna and half rectifier) can convert solar and infrared into electricity, plus be tuned to nearly any other frequency as a detector.

Right now efficiency is only one percent, but professor Baratunde Cola and colleagues at the Georgia Institute of Technology (Georgia Tech, Atlanta) convincingly argue that they can achieve 40 percent broad spectrum efficiency (double that of silicon and more even than multi-junction gallium arsenide) at a one-tenth of the cost of conventional solar cells (and with an upper limit of 90 percent efficiency for single wavelength conversion).

It is well suited for mass production, according to Cola. It works by growing fields of carbon nanotubes vertically, the length of which roughly matches the wavelength of the energy source (one micron for solar), capping the carbon nanotubes with an insulating dielectric (aluminum oxide on the tethered end of the nanotube bundles), then growing a low-work function metal (calcium/aluminum) on the dielectric and voila–a rectenna with a two electron-volt potential that collects sunlight and converts it to direct current (DC).

“Our process uses three simple steps: grow a large array of nanotube bundles vertically; coat one end with dielectric; then deposit another layer of metal,” Cola told EE Times. “In effect we are using one end of the nanotube as a part of a super-fast metal-insulator-metal tunnel diode, making mass production potentially very inexpensive up to 10-times cheaper than crystalline silicon cells.”

Read the full Article Here: Solar Cells Will be Made Obsolete by 3D rectennas aiming at 40-to-90% efficiency

 

DARPA Program Seeks to Use Commercial Drones


Image: A FLA quadcopter self-navigates around boxes during initial flight data collection using only onboard sensors/software. DARPA’s FLA program aims to develop and test algorithms that could reduce the amount of processing power, communications, and human intervention needed for unmanned aerial vehicles (UAVs) to accomplish low-level tasks, such as navigation around obstacles in a cluttered environment
Image: A FLA quadcopter self-navigates around boxes during initial flight data collection using only onboard sensors/software. DARPA’s FLA program aims to develop and test algorithms that could reduce the amount of processing power, communications, and human intervention needed for unmanned aerial vehicles (UAVs) to accomplish low-level tasks, such as navigation around obstacles in a cluttered environment

Inside the Otis Air National Guard Base—in Cape Cod, Mass.—the commercial DJI Flamewheel drone zipped down a row lined with cardboard boxes and tarps. At the end of the row, it smacked against the aircraft hangar’s floor, bounced, and tumbled to a stop.

The Defense Advanced Research Project Agency (DARPA) is playing with commercial drones. Well, not so much playing as experimenting.

 

Recently, DARPA’s Fast Lightweight Autonomy (FLA) program completed their first-flight data collection. In it, the program’s three performer teams demonstrated the commercial drone’s capability of reaching manned speeds up to 20 m/s, or 45 mph, and successfully navigating obstacles at slower speeds without human aid.

 

“Very lightweight UAVs (Unmanned Aerial Vehicles) exist today that are agile and can fly faster than 20 m/s, but they can’t carry sensors and computation to fly autonomously in cluttered environments,”said the program’s manager Mark Micire. “And large UAVs exist that can fly high and fast with heavy computing payloads and sensors on board. What makes the FLA program so challenging is finding the sweetspot of a small size, weight and power air vehicle with limited onboard computing power to perform a complex mission completely autonomously.”

The drone—outfitted with E600 motors, 12 in. propellers, and a 3DR Pixhawk autopilot—carried a variety of high-definition cameras and sensors, such as LIDAR, sonar, and inertial measuring instruments.

The three performances teams included Draper, which teamed with Massachusetts Institute of Technology; Univ. of Pennsylvania; and Scientific Systems Company, Inc., which teamed with AeroVironment.

According to Defense News, DARPA was offering $5.5 million in research funding for the program.

“We’re excited that we were able to validate the airspeed goal during the first-flight data collection,” said Micire. “The fact that some teams also demonstrated basic autonomous flight ahead of schedule was an added bonus. The challenge for the teams now is to advance the algorithms and onboard computational efficiency to extend the UAV’s perception range and compensate for the vehicles’ mass to make extremely tight turns and abrupt maneuvers at high speeds.”

Once fully developed, these drone systems will aid the military in surveillance operations, either patrolling hazardous urban environments or responding to disasters. As trials continue, the testing environment will grow more complex, with more obstacles added.

DARPA: New Nano-Material Could Change How We Work and Play


newmaterialworkplayx250Serendipity has as much a place in sci­ence as in love.

That’s what North­eastern Univ. physi­cists Swastik Kar and Srinivas Sridhar found during their four-year project to modify graphene, a stronger-than-steel infin­i­tes­i­mally thin lat­tice of tightly packed carbon atoms. Pri­marily funded by the Army Research Lab­o­ra­tory and Defense Advanced Research Projects Agency, or DARPA, the researchers were charged with imbuing the decade-old mate­rial with thermal sen­si­tivity for use in infrared imaging devices such as night-vision gog­gles for the military.

What they unearthed, pub­lished in Science Advances, was so much more: an entirely new mate­rial spun out of boron, nitrogen, carbon and oxygen that shows evi­dence of mag­netic, optical and elec­trical properties, as well as DARPA’s sought-after thermal ones. Its poten­tial appli­ca­tions run the gamut: from 20-megapixel arrays for cell­phone cam­eras to photo detec­tors to atom­i­cally thin tran­sis­tors that when mul­ti­plied by the bil­lions could fuel computers.

“We had to start from scratch and build every­thing,” says Kar, an assis­tant pro­fessor of physics in the Col­lege of Sci­ence. “We were on a journey, cre­ating a new path, a new direc­tion of research.”

newmaterialworkplayx250

An artistic ren¬dering of novel mag¬netism in 2D-BNCO sheets, the new mate¬rial Swastik Kar and Srinivas Sridhar cre¬ated. Image: Northeastern Univ.

The pair was familiar with “alloys,” con­trolled com­bi­na­tions of ele­ments that resulted in mate­rials with prop­er­ties that sur­passed graphene’s—for example, the addi­tion of boron and nitrogen to graphene’s carbon to con­note the con­duc­tivity nec­es­sary to pro­duce an elec­trical insu­lator. But no one had ever thought of choosing oxygen to add to the mix.

What led the North­eastern researchers to do so?

“Well, we didn’t choose oxygen,” says Kar, smiling broadly. “Oxygen chose us.”

Oxygen, of course, is every­where. Indeed, Kar and Sridhar spent a lot of time trying to get rid of the oxygen seeping into their brew, wor­ried that it would con­t­a­m­i­nate the “pure” mate­rial they were seeking to develop.

“That’s where the Aha! moment hap­pened for us,” says Kar. “We real­ized we could not ignore the role that oxygen plays in the way these ele­ments mix together.”

“So instead of trying to remove oxygen, we thought: Let’s con­trol its intro­duc­tion,” adds Sridhar, the Arts and Sci­ences Dis­tin­guished Pro­fessor of Physics and director of Northeastern’s Elec­tronic Mate­rials Research Institute.

Oxygen, it turned out, was behaving in the reac­tion chamber in a way the sci­en­tists had never antic­i­pated: It was deter­mining how the other elements—the boron, carbon and nitrogen—combined in a solid, crystal form, while also inserting itself into the lat­tice. The trace amounts of oxygen were, metaphor­i­cally, “etching away” some of the patches of carbon, explains Kar, making room for the boron and nitrogen to fill the gaps.

“It was as if the oxygen was con­trol­ling the geo­metric struc­ture,” says Sridhar.

They named the new mate­rial, sen­sibly, 2D-BNCO, rep­re­senting the four ele­ments in the mix and the two-dimensionality of the super-thin light­weight mate­rial, and set about char­ac­ter­izing and man­u­fac­turing it, to ensure it was both repro­ducible and scal­able. That meant inves­ti­gating the myriad per­mu­ta­tions of the four ingre­di­ents, holding three con­stant while varying the mea­sure­ment of the remaining one, and vice versa, mul­tiple times over.

After each trial, they ana­lyzed the struc­ture and the func­tional prop­er­ties of the product—elec­trical, optical—using elec­tron micro­scopes and spec­tro­scopic tools, and col­lab­o­rated with com­pu­ta­tional physi­cists, who cre­ated models of the struc­tures to see if the con­fig­u­ra­tions would be fea­sible in the real world.

Next they will examine the new material’s mechan­ical prop­er­ties and begin to exper­i­men­tally val­i­date the mag­netic ones con­ferred, sur­pris­ingly, by the inter­min­gling of these four non­mag­netic ele­ments. “You begin to see very quickly how com­pli­cated that process is,” says Kar.

Helping with that com­plexity were col­lab­o­ra­tors from around the globe. In addi­tion to North­eastern asso­ciate research sci­en­tists, post­doc­toral fel­lows, and grad­uate stu­dents, con­trib­u­tors included researchers in gov­ern­ment, industry, and acad­emia from the U.S., Mexico and India.

“There is still a long way to go but there are clear indi­ca­tions that we can tune the elec­trical prop­er­ties of these mate­rials,” says Sridhar. “And if we find the right com­bi­na­tion, we will very likely get to that point where we reach the thermal sen­si­tivity that DARPA was ini­tially looking for as well as many as-yet unfore­seen applications.”

Source: Northeastern Univ.

Theorists predict new state of quantum matter may have big impact on electronics


Printing Graphene Chips(Nanowerk News) Constantly losing energy is something we deal with in everything we do. If you stop pedaling a bike, it gradually slows; if you let off the gas, your car also slows. As these vehicles move, they also generate heat from friction. Electronics encounter a similar effect as groups of electrons carry information from one point to another. As electrons move, they dissipate heat, reducing the distance a signal can travel. DARPA-sponsored researchers under the Mesodynamic Architectures (Meso) program, however, may have found a potential way around this fundamental problem.
Meso program researchers at Stanford University recently predicted stanene will support lossless conduction at room temperature. Stanene is the name given by the researchers to 2-D sheets of tin that are only 1-atom thick. In a paper appearing in Physical Review Letters (“Large-Gap Quantum Spin Hall Insulators in Tin Films”) the team predicts stanene would be the first topological insulator to demonstrate zero heat dissipation properties at room temperature, conducting charges around its edges without any loss. Experiments are underway to create the material in laboratory conditions. If successful, the team will use stanene to enhance devices they are building under the Meso program.
the flow of electricity along the outside edges of a new topological insulator, stanene
This image depicts the flow of electricity along the outside edges of a new topological insulator, stanene. Theorists in DARPA’s Mesodynamic Architectures (Meso) program predict stanene would have perfect energy propagation properties at room temperature. (Image: SLAC National Accelerator Laboratory)
“We recently realized there is another state of electronic matter: a topological insulator. Materials in a topologically insulating state are like paying for the gasoline to accelerate your car to highway speeds, but then cruising as far as you want on that highway without using up any more gas,” said Jeffrey Rogers, DARPA program manager. “Experiments should tell us what penalty electrons would pay for connecting to stanene in a practical application. However, the physics of stanene point to zero dissipation of heat—meaning electrons take an entropy hit once and then travel unimpeded the rest of the distance.”
Researchers at Stanford reported the first topological insulators in 2006 under a previous DARPA effort known as the Focus Center Research Program. The current Meso program developed the theory for stanene as part of research into more efficient ways to move information inside microchips. Other materials’ capabilities have come close, but only at temperatures that require extreme sub-zero temperatures created with bulky methods such as liquid helium.
“Stanene is a bold, yet compelling prediction,” said Rogers. “If the experiments underway confirm the theory, the application of a new lossless conductor becomes a very exciting prospect in the world of electronics. A host of applications—almost any time information is moved electronically from one place to another—could benefit.”
Source: DARPA

Read more: http://www.nanowerk.com/nanotechnology_news/newsid=33742.php#ixzz2nlj7rvXP

Nanotechnology triples solar efficiency


By | December 11, 2012, 7:49 PM PST

Nanotechnology traps light for significantly greater solar efficiency.

Nanotechnology traps light for significantly greater solar efficiency.

Princeton University recently announced a new nanotechnology that has demonstrated the ability to triple the efficiency of solar cells by eliminating two of the primary reasons why light is reflected or lost. This breakthrough was achieved by applying a “nano-mesh” to plastics, which would make way for inexpensive, flexible devices, or even greatly improve the efficiency of standard photovoltaic panels, the researchers say.

The nano-mesh is designed to dampen reflection and trap light to be converted into electrical energy (existing technologies cannot fully capture light that enters the cell). Only 4 percent of light is reflected, and as much as 96 percent is absorbed, a press release noted. Its overall efficiency in converting light to energy is 52 percent higher than conventional cells in direct sunlight and up to 175 percent greater on cloudy days with less sun.

For reference, North Carolina’s Semprius Inc., a Siemens backed venture, revealed a prototype of what it called the world’s best solar efficiency at 33.9 percent earlier this year. Princeton didn’t reveal its overal efficiency.

Princeton’s findings were first reported in the November 2nd edition of the journal Optics Express, and exceeded the scientists’ expectations, according to project lead Dr. Stephen Chou. The research was funded by the Defense Advanced Research Projects Agency, the Office of Naval Research and the National Science Foundation. Chou said that the technology would become even more efficient with more experimentation.

Outside of the lab, U.S. PV maker ecoSolargy has already used nanotechnology to boost solar efficiency by an estimated 35 percent over a 20-year period by filling tiny holes that can accumulate dirt, dust, or water. Other approaches that are being taken to improve solar efficiency have been inspired by nature.

A team of researchers at the University of Wisconsin-Madison recently created a design that emulates how sunflowers move to maximize light exposure through an adaptation called heliotropism. One could imagine that any combination of these technologies would constitute another leap forward for solar power.

(Illustration by Dimitri Karetnikov/Chou Lab)QDOTS imagesCAKXSY1K 8

 

 

 

Making Nano-Fibers Affordable


QDOTS imagesCAKXSY1K 8Nanofibers — strands of material only a couple hundred nanometers in diameter — have a huge range of possible applications: scaffolds for bioengineered organs, ultrafine air and water filters, and lightweight Kevlar body armor, to name just a few. But so far, the expense of producing them has consigned them to a few high-end, niche applications.
Luis Velásquez-García, a principal research scientist at MIT’s Microsystems Technology Laboratories, and his group hope to change that. At the International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications in December, Velásquez-García, his student Philip Ponce de Leon, and Frances Hill, a postdoc in his group, will describe a new system for spinning nanofibers that should offer significant productivity increases while drastically reducing power consumption.
Using manufacturing techniques common in the microchip industry, the MTL researchers built a one-square-centimeter array of conical tips, which they immersed in a fluid containing a dissolved plastic. They then applied a voltage to the array, producing an electrostatic field that is strongest at the tips of the cones. In a technique known as electrospinning, the cones eject the dissolved plastic as a stream that solidifies into a fiber only 220 nanometers across.

In their experiments, the researchers used a five-by-five array of cones, which already yields a sevenfold increase in productivity per square centimeter over even the best existing methods. But, Velásquez-García says, it should be relatively simple to pack more cones onto a chip, boosting productivity even more. Indeed, he says, in prior work on a similar technique called electrospray, his lab was able to cram almost a thousand emitters into a single square centimeter. And multiple arrays could be combined in a panel to further increase yields.

Surfaces, from scratch
Because the new paper was prepared for an energy conference, it focuses on energy applications. But nanofibers could be useful for any device that needs to maximize the ratio of surface area to volume, Velásquez-García says. Capacitors — circuit components that store electricity — are one example, because capacitance scales with surface area. The electrodes used in fuel cells are another, because the greater the electrodes’ surface area, the more efficiently they catalyze the reactions that drive the cell. But almost any chemical process can benefit from increasing catalysts’ surface area, and increasing the surface area of artificial-organ scaffolds gives cells more points at which to adhere.

Watch the Video Here: http://youtu.be/eWGPW1tS38U

Another promising application of nanofibers is in meshes so fine that they allow only nanoscale particles to pass through. The example in the new paper again comes from energy research: the membranes that separate the halves of a fuel cell. But similar meshes could be used to filter water. Such applications, Velásquez-García says, depend crucially on consistency in the fiber diameter, another respect in which the new technique offers advantages over its predecessors.

Existing electrospinning techniques generally rely on tiny nozzles, through which the dissolved polymer is forced. Variations in operating conditions and in the shape of the nozzles can cause large variation in the fiber diameter, and the nozzles’ hydraulics mean that they can’t be packed as tightly together. A few manufacturers have developed fiber-spinning devices that use electrostatic fields, but their emitters are made using much cruder processes than the chip-manufacturing techniques that the MTL researchers exploited. As a consequence, not only are the arrays of tips much less dense, but the devices consume more power.
“The electrostatic field is enhanced if the tip diameter is smaller,” Velásquez-García says. “If you have tips of, say, millimeter diameter, then if you apply enough voltage, you can trigger the ionization of the liquid and spin fibers. But if you can make them sharper, then you need a lot less voltage to achieve the same result.”

Wicked wicker
The use of microfabrication technologies not only allowed the MTL researchers to pack their cones more tightly and sharpen their tips, but it also gave them much more precise control of the structure of the cones’ surfaces. Indeed, the sides of the cones have a nubby texture that helps the cones wick up the fluid in which the polymer is dissolved. In ongoing experiments, the researchers have also covered the cones with what Velásquez-García describes as a “wool” of carbon nanotubes, which should work better with some types of materials.

Indeed, Velásquez-García says, his group’s results depend not only on the design of the emitters themselves, but on a precise balance between the structure of the cones and their textured coating, the strength of the electrostatic field, and the composition of the fluid bath in which the cones are immersed.
“Fabricating exactly identical emitters in parallel with high precision and a lot of throughput — this is their main contribution, in my opinion,” says Antonio Luque Estepa, an associate professor of electrical engineering at the University of Seville who specializes in electrospray deposition and electrospinning.

“Fabricating one is easy. But 100 or 1,000 of them, that’s not so easy. Many times there are problems with interactions between one output and the output next to it.”

The microfabrication technique that Velásquez-García’s group employs, Luque adds, “does not limit the number of outputs that they can integrate on one chip.” Although the extent to which the group can increase emitter density remains to be seen, Luque says, he’s confident that “they can make a tenfold increase over what is available right now.”

The MIT researchers’ work was funded in part by the U.S. Defense Advanced Research Projects Agency.

MIT News: Making ‘nanospinning’ practical


Spinning nanofibers Nanofibers have a dizzying range of possible applications, but they’ve been prohibitively expensive to make. MIT researchers hope to change that.

Nanofibers — strands of material only a couple hundred nanometers in diameter — have a huge range of possible applications: scaffolds for bioengineered organs, ultrafine air and water filters, and lightweight Kevlar body armor, to name just a few. But so far, the expense of producing them has consigned them to a few high-end, niche applications.

Luis Velásquez-García, a principal research scientist at MIT’s Microsystems Technology Laboratories, and his group hope to change that. At the International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications in December, Velásquez-García, his student Philip Ponce de Leon, and Frances Hill, a postdoc in his group, will describe a new system for spinning nanofibers that should offer significant productivity increases while drastically reducing power consumption.

Using manufacturing techniques common in the microchip industry, the MTL researchers built a one-square-centimeter array of conical tips, which they immersed in a fluid containing a dissolved plastic. They then applied a voltage to the array, producing an electrostatic field that is strongest at the tips of the cones. In a technique known as electrospinning, the cones eject the dissolved plastic as a stream that solidifies into a fiber only 220 nanometers across.

In their experiments, the researchers used a five-by-five array of cones, which already yields a sevenfold increase in productivity per square centimeter over even the best existing methods. But, Velásquez-García says, it should be relatively simple to pack more cones onto a chip, boosting productivity even more. Indeed, he says, in prior work on a similar technique called electrospray, his lab was able to cram almost a thousand emitters into a single square centimeter. And multiple arrays could be combined in a panel to further increase yields.

Surfaces, from scratch

Because the new paper was prepared for an energy conference, it focuses on energy applications. But nanofibers could be useful for any device that needs to maximize the ratio of surface area to volume, Velásquez-García says. Capacitors — circuit components that store electricity — are one example, because capacitance scales with surface area. The electrodes used in fuel cells are another, because the greater the electrodes’ surface area, the more efficiently they catalyze the reactions that drive the cell. But almost any chemical process can benefit from increasing catalysts’ surface area, and increasing the surface area of artificial-organ scaffolds gives cells more points at which to adhere.

Watch YouTube Video from MIT on Nanofibers here:

Another promising application of nanofibers is in meshes so fine that they allow only nanoscale particles to pass through. The example in the new paper again comes from energy research: the membranes that separate the halves of a fuel cell. But similar meshes could be used to filter water. Such applications, Velásquez-García says, depend crucially on consistency in the fiber diameter, another respect in which the new technique offers advantages over its predecessors.

Existing electrospinning techniques generally rely on tiny nozzles, through which the dissolved polymer is forced. Variations in operating conditions and in the shape of the nozzles can cause large variation in the fiber diameter, and the nozzles’ hydraulics mean that they can’t be packed as tightly together. A few manufacturers have developed fiber-spinning devices that use electrostatic fields, but their emitters are made using much cruder processes than the chip-manufacturing techniques that the MTL researchers exploited. As a consequence, not only are the arrays of tips much less dense, but the devices consume more power.

“The electrostatic field is enhanced if the tip diameter is smaller,” Velásquez-García says. “If you have tips of, say, millimeter diameter, then if you apply enough voltage, you can trigger the ionization of the liquid and spin fibers. But if you can make them sharper, then you need a lot less voltage to achieve the same result.”

Wicked wicker

The use of microfabrication technologies not only allowed the MTL researchers to pack their cones more tightly and sharpen their tips, but it also gave them much more precise control of the structure of the cones’ surfaces. Indeed, the sides of the cones have a nubby texture that helps the cones wick up the fluid in which the polymer is dissolved. In ongoing experiments, the researchers have also covered the cones with what Velásquez-García describes as a “wool” of carbon nanotubes, which should work better with some types of materials.

Indeed, Velásquez-García says, his group’s results depend not only on the design of the emitters themselves, but on a precise balance between the structure of the cones and their textured coating, the strength of the electrostatic field, and the composition of the fluid bath in which the cones are immersed.

“Fabricating exactly identical emitters in parallel with high precision and a lot of throughput — this is their main contribution, in my opinion,” says Antonio Luque Estepa, an associate professor of electrical engineering at the University of Seville who specializes in electrospray deposition and electrospinning. “Fabricating one is easy. But 100 or 1,000 of them, that’s not so easy. Many times there are problems with interactions between one output and the output next to it.”

The microfabrication technique that Velásquez-García’s group employs, Luque adds, “does not limit the number of outputs that they can integrate on one chip.” Although the extent to which the group can increase emitter density remains to be seen, Luque says, he’s confident that “they can make a tenfold increase over what is available right now.”

The MIT researchers’ work was funded in part by the U.S. Defense Advanced Research Projects Agency.