Scientists and engineers dream about big advances that could change the world, and then they try to create them. On the following pages, Scientific American reveals 10 innovations that could be game changers: an artificial alternative to DNA, oil that cleans water, pacemakers powered by our blood, and more. These are not pie-in-the-sky notions but practical breakthroughs that have been proved or prototyped and are poised to scale up greatly. Each has the potential to make what may now seem impossible possible. —The Editors
New Life-Forms, No DNA Required
Artificial organisms based on man-made molecules could thrive and evolve
DNA is passé. Synthetic biologists have invented an array of new molecules called XNAs that boast all the talents of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), as well as some special powers. XNAs could allow scientists to safely create life-forms in the laboratory that do not depend on DNA to survive and evolve.
“Life is inconceivable without a system for genetic information storage and replication, but DNA and RNA are not unique,” explains Philipp Holliger of the Medical Research Council's Laboratory of Molecular Biology in Cambridge, England. “Related polymers—at least six more—can do the same function.” That the earth's flora and fauna rely only on DNA and RNA, he says, is an “accident from the origin of life.”
XNA stands for xeno nucleic acid (xeno meaning “foreign”). Like DNA, XNA has a structure that resembles a twisted ladder. In DNA, four different nucleobases, represented by the letters A, C, G and T, form the steps. Phosphate groups and sugars form the ladders' sides, also known as the backbone. For 30 years scientists have been tweaking the sugars to create artificial nucleic acids, which serve as research tools in medicine that can bind to DNA.
To make XNAs, Holliger and his colleagues did not simply alter the sugars in DNA's backbone—they substituted entirely different molecules, such as cyclohexane and threose. Just as important, they created enzymes that work with the XNAs to form a complete genetic system.
The enzymes enable XNAs to do something no other artificial nucleic acids can do: they evolve. Inside living cells, enzymes called polymerases cut, paste and splice DNA to access the genetic information. Without that interaction, DNA would remain as inert as dusty encyclopedias on a shelf. Holliger reprogrammed natural polymerase enzymes to translate DNA into XNA and back again, establishing a novel system for storing and transmitting genetic information, which is the foundation of evolution. One of the XNAs, HNA (anhydrohexitol nucleic acid), reliably preserved changes to its genetic code and evolved to attach to a protein with increasing precision.
Once Holliger improves the functionality of XNA and its enzymes, the set of molecules could replace DNA and RNA in a living cell. Researchers might take a simple bacterium, for instance, suck out its DNA and replace it with XNA.
Alternatively, scientists could enclose XNA within protocells—the origin of a new life-form that could evolve in ways no one can predict. Whereas other synthetic biologists such as J. Craig Venter have made remarkable advances in rewriting the existing genetic code, no one has created truly synthetic life—life that does not depend on what evolution has already provided but on humankind's inventions.
Holliger emphasizes that XNA-based life-forms are a long way off, but he already recognizes a distinct advantage. If such a creature escaped into the wild, it would die without a steady supply of XNA-specific enzymes. And XNA could not weave itself into the genomes of natural organisms, because their native enzymes would not recognize it. XNA-based bacteria designed to devour oil spills or turn wastewater into electricity, for example, could not interfere with native organisms.
The fact that XNA is complementary to DNA, yet structurally unique, makes it immediately useful for medicine, biotechnology and biology research. Holliger imagines XNAs that could be injected into the human body to detect early, subtle signs of disease that current technologies miss.
Steven Benner, a fellow at the Foundation for Applied Molecular Evolution in Gainesville, Fla., has also advanced the effort by expanding the genetic alphabet with two new nucleobases, Z and P. A larger alphabet could form a wider array of genes and, eventually, proteins. “The goal is to create chemically controlled systems that behave like biological systems, without being biological systems,” Benner says. “We believe whatever you can draw on a page, you can make.” — Ferris Jabr
Foam That Restores Breathing
Injectable oxygen microbubbles could give asthma and choking victims precious minutes
Only a few minutes after someone stops breathing—whether it is from a piece of meat stuck in the throat, a severe asthma attack or a lung injury—the brain starts to shut down. Cardiac arrest and death are imminent. Emergency responders and hospital workers have one primary recourse: insert a breathing tube through a patient's mouth. That procedure can be risky and time-consuming.
A new injectable solution could keep such people alive for 15 minutes or more, buying crucial time to get victims to a hospital or to do some surgical gymnastics in an operating room. The solution contains oxygen microbubbles, which the blood can absorb within seconds. The bubbles are too small to cause an air embolism—a gas pocket that stops blood flow, thus causing a stroke or heart attack.
To create this lifesaving foam, John Kheir, a cardiologist at Boston Children's Hospital, and his colleagues adapted existing medical nanotechnology. Microparticles with lipid membranes already deliver drugs, as well as dyes for ultrasound imaging. Kheir's team propelled phospholipids through an oxygenated chamber and used sound waves to spur the ingredients to self-assemble into microparticles. The researchers then used a centrifuge to superconcentrate them into solution. Each four-micron-wide microbubble contains pure oxygen, surrounded by a lipid film that is just a few nanometers thick.
Because the bubbles contain oxygen at a pressure that is higher than in the bloodstream, the gas diffuses into red blood cells on contact. Once a bubble is depleted, the shell collapses to a disk that is less than a micron wide, easily passing through the circulatory system.
In a test, researchers blocked the airways of anesthetized rabbits for 15 minutes. Those injected with the solution were much less likely to go into cardiac arrest or have other organ damage than those who got saline solution—despite not taking a single breath.
The approach is “a fairly innovative idea compared to what we have now,” says Raymond Koehler of Johns Hopkins University, who is not involved in the work, because most emergency oxygen procedures require the pulmonary system to function at least at a minimal level.
One drawback is that because the blood absorbs the oxygen so quickly, a constant infusion is necessary, which involves a lot of saline to help the foam move smoothly into the bloodstream. The amount of solution that a patient would receive after 15 minutes could lead to edema, a fluid overload that can cause heart failure. Kheir's team is trying to improve the formulation so that it requires less saline.
Another concern is that without normal respiration, carbon dioxide builds up in the body, which can be toxic. As Koehler notes, however, the body can handle a little excess carbon dioxide better than it can handle a total lack of oxygen. If the microbubbles prove successful in further animal (and subsequent human) trials, the solution could help emergency crews or operating room technicians buy crucial minutes before they can implement other lifesaving treatments. In those situations, Koehler says, “you want to have a backup plan.” — Katherine Harmon
Water Purified with Oil
A simple chemical trick could clean wastewater much less expensively
Anurag Bajpayee started out looking for a better way to preserve human cells in deep freeze. Such cryopreservation must carefully avoid frostbite—the formation of ice crystals that rupture and kill cells. In 2008, while conducting experiments at Massachusetts General Hospital, Bajpayee inserted the antifreeze glycerol into the cells, along with soybean oil, which helped to concentrate the glycerol. During his Ph.D. qualifying exam the next year, at the Massachusetts Institute of Technology—typically a tense affair—a curious conversation broke out with his interviewers when he described the soybean oil's effect. Why not use the soybean oil, they proposed, to remove impurities from water? “I think it's one of the very few qualifying exams that resulted in a patent application,” Bajpayee says.
Bajpayee soon created a simple process that uses an unusual class of oils to take contaminants out of water. The process could be a boon to cities, industries and agricultural operations—all of which create vast amounts of dirty water—by providing ways to clean that water that could be much less energy-intensive or expensive, or both.
Soybean oil is among a small number of oils that seem to serve as so-called directional solvents. That is, they dissolve water without dissolving other molecules that are in the water, such as salts. Soybean oil can absorb water when heated to as little as 40 degrees Celsius, leaving behind contaminant molecules, which are then skimmed away. Simply cooling the mixture allows the cleansed water to flow back out to be captured. The solvent thus remains undisturbed, ready to clean more water.
The key is the carbon backbone of the oil, a fatty acid. Most of it repels water, but at one end is a molecule, known as a carboxylic acid group, that readily forms a hydrogen bond with water.
“It surprised me that it would actually work,” says organic chemist Jean-Claude Bradley of Drexel University, who also noted that the phenomenon could have been discovered a century ago. “It's the coolest thing I've seen in chemistry for a long time.”
Bajpayee's experiments showed, however, that purifying a single cup of water would require enough soybean oil to fill a swimming pool. So he looked for another directional solvent that would be more efficient and settled on decanoic acid, which occurs naturally in milk and which bonds even more readily to water. This fatty acid could turn seawater into fresh, but it appears to work best for even saltier brines, such as the residue of mining or the chemical-laden water that flows back up oil and gas wells, including fracking wells. “If you thought that seawater was salty, this is eight times saltier,” Bajpayee notes of the more than nine billion liters of contaminated water produced by the nation's oil and gas wells every day.
Encouraged, Bajpayee is already testing decanoic acid against six different oil and gas brines that were taken from different parts of the U.S. Conventional technologies for treating such wastewater include reverse osmosis, which requires special membranes that can clog and foul easily; distillation, which consumes copious amounts of energy; and, most commonly, dumping the water back down a disposal well. Bajpayee will also need to figure out a way to speedily process wastewater continuously rather than treating batches of it in beakers and test tubes.
To make a real impact in oil and gas drilling, “we'll have to beat the cost of the cheapest alternative, which right now is dumping,” Bajpayee admits, although more and more communities do not want wastewater sent underground and lost that way. In the meantime, more research will tell if decanoic oil or some other directional solvent could cleanse dirty wastewater or desalinate seawater more inexpensively than current processes—giving water treatment a new direction. — David Biello
Early Treatment for Alzheimer's
A drug trial of 300 Colombians could reveal a way to prevent the disease from ever starting
Alzheimer's disease remains virtually untreatable. More than 100 experimental drugs have failed to halt the condition that robs people of their memories, their relationships and, ultimately, their identity. Now scientists will be testing a new strategy for preventing this horrific condition from starting in the first place. Just as healthy people take statins to lower their cholesterol and avoid heart disease, people at risk for Alzheimer's could conceivably pop pills to keep the disease at bay.
Researchers will be investigating a drug that flushes away an intrusive protein called amyloid, suspected as a primary contributor to Alzheimer's. Until recently, amyloid clumps could only be seen by dissecting the brain after death. Yet advanced positron-emission tomography scans of living people's brains, a recent innovation, show that by the time symptoms appear, amyloid has been silently accumulating for up to 20 years. Perhaps by then the brain is irreversibly damaged, making any drug useless. No one knows for sure, however, whether amyloid causes Alzheimer's or is merely a by-product of the disease. The new study may provide an answer to this mystery.
Set to start early in 2013 if all approvals are granted, the investigation will involve 300 members of distantly related families in Colombia whose rare and particularly devastating form of Alzheimer's strikes in the prime of life. By their 50s and 60s, many are as helpless as infants. Normally it is impossible to predict who will develop Alzheimer's, but in this extended family, a single genetic mutation, detectable by a blood test, spells doom.
Eric Reiman, executive director of the Banner Alzheimer's Institute in Phoenix, his colleague Pierre Tariot and their Colombian collaborator Francisco Lopera realized that the family provided a unique opportunity to test the benefits of early intervention. They plan to give an experimental drug, crenezumab, to 100 family members who are on the cusp of developing Alzheimer's symptoms and a placebo to 100 others. A third group not destined to get the disease will also receive the placebo.
Participants will receive biweekly injections for at least five years. Every few months they will undergo extensive testing: magnetic resonance imaging to track brain shrinkage; spinal taps to measure tau protein, which is associated with brain cell death; and memory and thinking tests designed to pick up subtle cognitive lapses, such as forgetting a list of words that were memorized only minutes or hours earlier, a marker of emerging Alzheimer's.
The study will also enlist up to three dozen patients in the U.S. The Americans, who will receive the same treatment, will be a less homogeneous bunch, possessing various mutations in any of three genes linked to early-onset Alzheimer's. Investigators hope to learn whether it is possible to extrapolate from the Colombian family to others who are destined to develop dementia in middle age.
The $100-million study is funded by the drug's maker, Genentech, as well as by philanthropists and the National Institutes of Health. Even if the drug succeeds, there is no guarantee that the results will translate to the much more common form of Alzheimer's that afflicts the elderly. Yet the researchers hope this trial will establish for Alzheimer's what cholesterol and high blood pressure are for cardiovascular disease—intermediate signposts that aid research, diagnosis and treatment.
The data they collect could mean that instead of having to wait years to see whether an experimental drug helps patients, researchers could quickly gauge results from subtle biological shifts such as smaller brain size or changes in tau or amyloid deposits. “We need to develop faster ways to test the range of promising therapies and find ones that work as soon as possible,” Reiman says. —Emily Laber-Warren
Genome Sequencing for Fetuses
A noninvasive procedure could reveal thousands of disorders not discernible now
Researchers have recently shown that they can construct a complete genetic picture of a fetus—the full genome—simply by taking a blood sample from the mother. The procedure could revolutionize genetic screening by revealing single-gene disorders such as cystic fibrosis, Tay-Sachs disease or fragile X syndrome long before a fetus is born—giving doctors time to begin possible prenatal therapies and giving families time to prepare for their child's needs.
One percent of the population lives with a single-gene disorder. Since 2011 doctors have been able to determine from a mother's blood sample if her fetus has an abnormal chromosome, which could indicate conditions such as Down syndrome. That level of information cannot reveal most of the roughly 3,500 single-gene disorders, however. Physicians can withdraw a placental tissue or an amniotic fluid sample to check for those conditions, but these invasive tests carry a risk of miscarriage women may not be willing to take.
The new noninvasive approach would give mothers unprecedented detail about their child without endangering their pregnancy. It could also reach more women worldwide because the procedure does not require a trained obstetrician. Some researchers envision do-it-yourself kits that mothers would send to a lab.
The procedure stems from a discovery made in 1997, when chemical pathologist Dennis Lo, then at the University of Oxford, and his colleagues detected the presence of fetal DNA in a pregnant woman's blood plasma. That meant it was possible to separate the two DNA types and use the fetal portion to construct a full genome. Researchers started looking for haplotypes—clusters of adjacent gene sequences. Different search methods could distinguish the variety of haplotypes in a plasma sample and indicate which came from the mother or fetus. The haplotypes could then be reassembled into a full genome.
The approach was easier said than done; it would require sophisticated technology that has only recently become practical. In the past year geneticist Jay Shendure of the University of Washington de-veloped a technique that entailed sequencing a full paternal and maternal genome from a father's saliva and a mother's blood, then using those data to distinguish between maternal and fetal haplotypes in the mother's plasma. In the process, Shendure can discern mutations that arise spontaneously in the fetus, which could help in spotting rare conditions.
Scientists led by Stanford University bioengineer Stephen Quake have reconstructed the fetal genome using only a maternal blood sample. They first seek haplotypes that the fetus inherits from the mother, which will likely be the most common in the plasma because mother and child share them. Quake then uses genetic markers from the mother to identify the rest of her genome. Haplotypes that do not appear in the mother's genome are unique to the fetus and may have come from the father or a mutation.
Despite progress, challenges remain—notably, lowering the cost and raising the accuracy of sequencing. The larger challenge is how to interpret the genome. “Our ability to detect genomic changes has outpaced our ability to correlate many of those changes with human diseases and characteristics,” says Brenda Finucane, president of the National Society of Genetic Counselors. Many doctors believe it is premature to embrace screening before clear guidelines are set for its use.
Critics also fear that the procedure could lead to abortions, as parents discover that their fetus has an incurable condition. Yet doctors such as Diana Bianchi of Tufts University believe the benefits could outweigh fears—particularly if screening enables prenatal treatments that can alter debilitating diseases. — Daisy Yuhas
The Ultimate Sustainability Index
A new rating system exploits corporate pressure to clean up all stages of the supply chain
How “sustainable” is a can of soda or a bottle of shampoo? An increasing number of consumers want to base their buying decisions on the answer, but finding a comprehensive measure for the negative impact that the making of a product might have on the planet is difficult. Scores of “sustainability indexes” scrutinize discrete stages of the supply chain or different effects—such as landfill waste generated or carbon dioxide emitted—and use different metrics supported by different groups. The problem is not a lack of information; it is too much of it.
Judging products would be much easier if there were one set of metrics to evaluate environmental and social costs. That is the idea behind the Sustainability Consortium, a collection of 10 leading universities, large nonprofit organizations and 80 international companies—including Walmart, Coca-Cola and Disney—that have agreed to devise a standard index covering the entire supply chain. The group recently unveiled the measures its members will use to evaluate a first set of 100 products, ranging from breakfast cereals to laundry detergents to televisions.
Advocates such as Jeff Rice, Walmart's director of sustainability, argue that sustainable practices across the supply chain not only can clean up the environment but also can cut costs by, for instance, reducing the amount of waste that needs to be hauled away. Walmart is building the metrics into “scorecards” that it has begun distributing to the roughly 400 buyers who procure the retailer's products. Buyers will develop plans with suppliers to reduce environmental impacts, and whether suppliers act will be discussed in the buyers' performance reviews.
Consortium member Dell is already asking contractors that produce its LCD screens to figure out how to reduce the emission of perfluorocarbons (powerful greenhouse gases) created when the screens are manufactured. The consortium's data “gave us a guide of where to target our efforts,” says Scott O'Connell, director of environmental affairs at Dell.
The consortium believes its index will ultimately supersede other ratings schemes. Consumers can already walk into a grocery store, whip out their mobile phones, scan a bar code on a bottle of shampoo and pull up a sustainability ranking compiled by GoodGuide. But the guide is built only on publicly available information. The consortium's ratings will factor in closely held data on emissions, waste, labor practices, water usage and other sensitive factors that will become available only as large corporate players exert pressure on suppliers to disclose them. The data should make the index more comprehensive than others. Companies the size of Walmart, Best Buy and Dell control hundreds of billions of dollars in annual spending by suppliers. “That in and of itself is going to make sustainability more mainstream than anything else ever has,” Rice says.
It will be several years before consumers can access the index's data. Consortium leaders expect to make it available but have not yet determined how consumers would be able to access it. In the meantime, the index could spur innovation. Researchers at the University of California, Berkeley, for one, produced a white paper for the consortium reviewing the advantages of using bio-based materials in laptops instead of plastics. And scientists at the University of Arkansas are studying the best ways to evaluate impacts of various crop practices on water scarcity. — Adam Piore
Mining the Mobile Life
A wealth of data from smartphones is waiting to change our lives, if only we let it
The dream—or nightmare—of near-flawless surveillance is on us, and it is starting to change our lives in ways few of us could have imagined. Companies that parse location data emitted by our cell phones can now accurately predict where each of us will be at any point during the day. They can also figure out from phone records who our friends, family and co-workers are, when we are likely to get the flu, and what the demographics of any major metropolitan street corner will be at any moment.
The key to this explosion of data is smartphone penetration, which surpassed 50 percent in the U.S. this year. Nearly every one of those devices, by default, sends a steady stream of location data back to centralized servers because few users bother to opt out of such data collection or are even aware that they can. Scientists and commercial researchers are figuring out how to plow through the billions of coordinates, enough to chart the movements of millions of people.
This reality mining, a classic “big data” challenge, is in its infancy. Companies are just beginning to sell the data to marketers, and cell phone carriers are releasing to researchers only limited data sets that are “anonymized” to preserve the privacy of individuals. The three biggest players—Google, Apple and Skyhook in Boston, one of the original location service providers—are all treading lightly in handling this information, for fear that intrusive uses might provoke a consumer backlash.
The technology could provide widespread benefits such as fewer annoying ads and the containment of disease outbreaks. Yet to the few consumers who are aware of it, “this is very scary stuff—it's Promethean fire,” says Alex “Sandy” Pentland, who coined the term “reality mining” when he and his students pioneered the analysis of smartphone location data in the mid-2000s.
Currently firms such as Skyhook and PlaceIQ in New York City that repackage data for marketers are careful to make location traces on individual devices unavailable. Google says that it deletes almost all location data after about a week. Apple made the mistake of storing such data on the iPhone itself; the company has since rectified this faux pas, but it is still less than forthcoming about how it stores such information centrally and what it plans to do with it.
If the privacy concerns holding back greater use of the data can be addressed, reality mining could become essential to how we navigate our everyday lives, not to mention enormously useful for corporations and governments. For example, work in Haiti allowed relief agencies to send texts to cell phone users whose location histories indicated that they might have been exposed to cholera.
For reality mining to really take off, consumers would have to authorize use of even more of their data. That is one reason why Pentland pushed discussions that led to the proposal of the Consumer Privacy Bill of Rights in the U.S. and an update to the European Union's Data Protection Directive. If users feel like they control their data, they are more likely to let companies, governments and individuals selectively access the information to provide services. “There's no part of society that's not going to use these data,” says Ted Morgan, CEO of Skyhook. “It fundamentally changes how you view human behavior.”
Insights into consumer behavior could expand as a result. Researchers have already found that the people most likely to click on a smartphone ad—and therefore who offer the highest payoff to advertisers—are those who are sitting in a movie theater before a film has begun, anyone at home on a Sunday morning and fishers waiting for a bite. (PlaceIQ can guess that individuals are fishing because their coordinates put them in the middle of a lake and they happen to match a particular demographic profile.)
Pentland believes that once enough data are available, reality mining will enhance public health, transportation and the electric grid, just for starters. “I like this notion of society's nervous system,” Pentland says. “Finally, humanity can sense what humanity is doing.” — Christopher Mims
The glucose in our blood could drive medical implants
Pacemakers, insulin pumps and other medical devices of the future may run without batteries, powered instead by the same energy that fuels the body: sugar. Researchers first dreamed of glucose-powered implants in the 1960s, but the advent of lithium batteries in the late 1970s provided a simpler, more powerful fix.* Batteries have always had a major drawback, however: they must be surgically replaced—every five to 15 years for pacemakers. Rechargeables connect to electronics outside the body with wires that pierce the skin and leave a person open to infection.
Several advances have prompted researchers to look again at glucose, which is plentiful in blood and the interstitial fluid that bathes our cells. More efficient circuitry in implants, for example, has reduced power requirements. And glucose biofuel cells are becoming much more efficient and body-friendly.
In most biofuel cells, enzymes at the anode strip electrons from glucose molecules. The electrons provide current as they flow to the cathode, where they react with oxygen, forming only small amounts of water. Unlike batteries, however, fuel cells need to be immersed in a constant supply of fuel—which blood or interstitial fluid can readily provide.
Excitement started to build in 2003, when researchers at the University of Texas at Austin built a tiny biofuel cell that generated power from a grape. Since then, a handful of groups have demonstrated practical devices. Past models demanded acidic conditions not found in the body, but researchers at Joseph Fourier University in Grenoble, France, packed biocompatible enzymes on a graphite base, which produced a milder chemistry. Their disk-shaped cell is half the diameter of a dime and slightly thinner. It is wrapped in material used for dialysis bags, which allows small molecules of glucose in but keeps enzymes from getting out. In a 2010 lab rat experiment, the device drew glucose from interstitial fluid and produced a stable power output of 1.8 microwatts for 11 days.
This year researchers at the Massachusetts Institute of Technology took another step toward commercialization. Engineer Rahul Sarpeshkar built a fuel cell as an integrated circuit on a silicon chip, using “the same easy-to-manufacture process as semiconductors,” he says. His team wants to use cerebrospinal fluid to power brain-machine interfaces. The fluid, which cushions the brain and spinal cord, contains plenty of glucose yet few immune system cells that could work to reject the implant.
Sarpeshkar has crafted platinum electrodes, which do not irritate tissue or corrode, notes Sven Kerzenmacher, a chemical engineer at the University of Freiburg in Germany, who is also using the material in his designs. Still, the body can mount opposition to such an incursion; Kerzenmacher says biocompatibility is the biggest hurdle. His prototype fuel cell works well in buffer solutions in the lab, he says, but in body-fluid tests, amino acids in blood or serum caused the device to lose power.
While a Clarkson University group has implanted a biofuel cell in a snail, the Grenoble group is still the only one to successfully operate a glucose fuel cell inside a vertebrate. The M.I.T. design has not been tested in cerebrospinal fluid but in a buffer that approximates body-fluid chemistry. Yet Sarpeshkar is optimistic that biofuel cells could enter the market in 10 years. His silicon device produces a reliable power output of 3.4 microwatts per square centimeter. Current pacemakers need eight to 10 microwatts, a feasible goal. Cochlear implants require a few milliwatts, and artificial organs would require even more.
As sugar-powered implants advance, they are opening up the possibility of tiny medical devices. Perhaps nanoscale robots that run on glucose and dispense targeted drugs will one day swim from science fiction to reality. — Marissa Fessenden
Ultrathin, flexible sensors could adorn packaging, accessories, even our bodies
Engineers have built circuitry on flexible plastics, but electronics may soon reach a far more pliable realm: circuits that we can wear on our bodies, like tattoos, to monitor our vital signs. The circuits could also be woven into clothing to power our smartphones and into food packaging to alert us about contamination.
Rather than looking for flexible substances that can conduct electricity, John Rogers, a materials scientist at the University of Illinois at Urbana-Champaign, got the idea to take common silicon circuitry and make it bendable. He and engineers at mc10, a firm in Cambridge, Mass., sanded silicon microchips, usually millimeters thick, down to 10 or 20 microns using well-established manufacturing processes. They also devised ultrathin wires to connect those chips to one another and to traditional input-output ports—wires that can bend, fold and stretch up to twice their original dimension.
Kevin Dowling, vice president of research and development at mc10, likens this configuration to “islands [the chips] that are anchored and oceans of interconnects” between them that can stretch or bend. “If you take a Slinky made of spring steel, that steel itself doesn't stretch very much,” Dowling explains. “But a Slinky can stretch 40 to 50 times its original length without exceeding the plastic limits of the steel. In the same way, we can create metal or silicon interconnects.”
Rogers, who co-founded mc10 and whose laboratory is the company's de facto R&D operation, says that in the next five to 10 years stretchable electronics will show up in forms no thicker than a Band-Aid. These sensors could monitor a person's body and transmit the results wirelessly. Already mc10 has a contract with Reebok for an apparel-based health monitor. The company also has a contract with the U.S. Army to determine whether it can produce flexible solar cells that can be integrated into soldiers' clothing and backpacks. In April, NASCAR driver Paulie Harraka tested a transparent skin patch during a race. The patch measured Harraka's level of hydration, an important consideration in a cockpit that can roast drivers for hours. Other engineers are also pursuing flexible biomedical tattoos, including Nanshu Lu of the University of Texas at Austin and a team at Korea University in Seoul.
Band-Aid-like sensors could stay on the body for up to a week, acting as “biostamps” or medical tattoos that could measure heart rate and perspiration. The circuitry is so thin and transparent that it looks like a small, see-through film on the skin.
The circuitry could one day be embedded inside the heart or the brain. Rogers imagines that hearts with arrhythmias could be sheathed in an artificial sac that would electronically sense and correct the organ's flawed rhythm. Such a sheath could deliver variable electrical stimulation to any location on the heart, thereby creating a much more nuanced shaping of the heart's beating than a pacemaker. Rogers also envisions “artificial skin over a burn site to provide artificial vasculature and, at the same time, drug delivery and stimulation to accelerate healing of that wound.”
If mc10's technology scales up, one product could be a roll of stickers, each one a sensor. A person could bug a room with tiny stickers designed to pick up sound. Anything that a silicon chip can sense—strain, vibration, electric fields—could be measured by little paper-thin sensors. Worn on the body or in clothing, such devices could be powered by weak electromagnetic fields and could then use those same fields to report back via people's smartphones.
Wide application will depend on manufacturing innovations from electronics makers that license mc10's technology. As with other transformative electronics innovations—think of the LEDs that now light up everything from household bulbs to grocery stores—it is ultimately up to the thousands of consumer device makers to figure out how best to apply this foundational technology. —Christopher Mims
Drones at Home
Tiny, unmanned aircraft are ready to warn you about traffic or spy on you in your backyard
Airborne eyes that peer down from the sky are already changing how science gets done and how wars are fought, and a commercial fleet of them is destined to radically change how we live our lives.
Scientists such as Lian Pin Koh of the Swiss Federal Institute of Technology and Serge Wich of Liverpool John Moores University in England are helping to create that intriguing and possibly unnerving future. After spending two and a half years and $250,000 tracking orangutans in Sumatra on foot, Koh and Wich devised a quicker, cheaper method. They bought a battery-powered model airplane and added an inexpensive open-source autopilot and high-resolution camera. For less than $2,000, they created a Conservation Drone—an autonomous plane with a 4.5-foot wingspan that uses GPS signals to fly preprogrammed routes and bring back remarkably detailed pictures and data about orangutan nests and new areas of deforestation. “We're still surprised how easy it was to assemble from off-the-shelf components,” Koh says.
The first tests in early 2012 were so successful that other conservationists have been clamoring for their own planes. Working with a Swiss startup company, Koh and Wich have now built more than 20 drones.
The military already depends on big drones such as the Predator to fight enemies and on small autonomous planes and helicopters to scout paths for convoys or ferret out ambushes. Officers use them to find illegal activity along the U.S.-Mexico border. But civilian enthusiasts are getting into the act, too; they have customized drones to nab polluters, inspect drilling rigs, and take stunning pictures for movies and real estate listings. “Drones are going to change the world in profound ways,” says Matthew Waite, a journalist-turned-professor at the University of Nebraska–Lincoln who is exploring the use of drones for journalism.
This revolution is being propelled by rapid advances in technology. With powerful smartphone chips and open-source hardware platforms such as Arduino, do-it-yourselfers and communities such as DIY Drones have begun to build inexpensive but sophisticated autopilots that transform radio-controlled aircraft into autonomous ones. Companies that build drones for the military are pitching their wares to police departments and government agencies. The U.S. Department of the Interior has already obtained 60 Raven planes, weighing 4.8 pounds apiece, from aviation pioneer AeroVironment, to observe roosting sandhill cranes and measure stream temperatures and sediment flows, among other tasks. Future possibilities seem endless: with sophisticated cameras and sensors, small drones could tell when crops need water, chart oil spills and report on traffic jams. “We're just at the tip of the iceberg of what's possible,” says Mike Hutt, manager of the U.S. Geological Survey's National Unmanned Aircraft Systems Project Office.
The full iceberg will not come into view for several years, however, because the Federal Aviation Administration has banned commercial uses of drones, fearing the confusion and accidents that could occur if thousands of unmanned craft take to already crowded skies. The FAA basically allows flying by hobbyists, government agencies and researchers and usually limits the altitude to a few hundred feet. But the FAA Modernization and Reform Act of 2012, signed by President Barack Obama in February, requires the agency to develop rules permitting more civilian uses. The FAA is working with companies on the key technology: systems that allow drones to sense and avoid other flying objects. Final rules are expected by 2015, opening the door to an explosion of commercial applications.
The current pause before that explosion is a boon, Waite suggests. “Drones raise humongous questions about safety and ethics and law and privacy,” he says. “But now we have a rare opportunity to think about how we are going to use a technology before we actually use it.”
— John Carey
For more World Changing Ideas, including robot lifeguards, see ScientificAmerican.com/dec2012/world-changing-ideas