Undergraduates can pursue programs in Computer Science (A.B. and as a secondary field), Engineering Sciences (A.B. and S.B., both of which are ABET accredited), and Applied Mathematics (A.B. and as a secondary field).
At the graduate level, the Division offers S.M., M.E., and Ph.D. options covering interdisciplinary research areas including: Applied Mathematics, Applied Physics, Bioengineering, Chemical Engineering, Computer Science, Electrical Engineering, Environmental Sciences and Engineering, Mechanical Engineering. In addition graduate students may pursue collaborative options: Engineering and Physical Biology (with the Faculty of Arts and Sciences); Science, Technology and Management (joint with the Harvard Business School); Medical Engineering and Medical Physics; (Harvard/MIT Division of Health Sciences and Technology); and Systems Biology (with Harvard Medical School).
Faculty number approximately seventy (73 FTEs) who account for nearly $40M in annual research funds (2007/8 figure). These faculty members have particularly close ties (and there are multiple joint appointments) with the departments of Physics, Earth and Planetary Science, and Chemistry and Chemical Biology. The facilities provide 400,000 square feet (37,000 m2) of interconnected labs, classrooms, clusters, and offices in six buildings.
Areas of particular research focus at SEAS include Applied Mathematics, Applied Physics, Bioengineering, Computer Science, Electrical Engineering, Environmental Sciences and Engineering, and Mechanical Engineering.
Harvard School of Engineering and Applied Sciences (SEAS) research articles from Innovation Toronto
- Creating a new vision for multifunctional materials – November 29, 2015
- Dive of the RoboBee – October 22, 2015
- Super-slick material makes steel better, stronger, cleaner – October 21, 2015
- Home Battery: Green storage for green energy grows cleaner – September 26, 2015
- Greening the electric grid with gas turbines – September 22, 2015<
- Printing lightweight, flexible, and functional materials – September 22, 2015
- Perfect colors, captured with one ultra-thin lens – February 22, 2015
- Boston’s natural gas infrastructure releases high levels of heat-trapping methane – January 24, 2015
- Hands on: Crafting ultrathin atoms-thick color coatings on paper – December 25, 2014
- Airway muscle-on-a-chip mimics asthma – September 29, 2014
- For electronics beyond silicon, a new contender emerges – September 18, 2014
- Cheap and compact medical testing – August 19, 2014
- A self-organizing thousand-robot swarm – August 15, 2014
- Carbon-fiber epoxy honeycombs mimic the material performance of balsa wood – June 26, 2014
- Researchers use light to coax stem cells to repair teeth – May 29, 2014
- ‘Heart disease-on-a-chip’ – May 12, 2014
- Brighter inks, without pigment and they never fade | structural color
- An Essential Step toward Printing Living Tissues | Printing Living Tissue
- Robotic construction crew needs no foreman
- Electrical generators driven by changes in humidity from sun-warmed ponds and harbors
- Organic mega flow battery promises breakthrough for renewable energy
- Programming smart molecules: Could Make Chemical Reactions Intelligent
- Synaptic transistor learns while it computes
- Entering a New Dimension: 4D Printing
- Cross-Disciplinary Team From Harvard and Dana-Farber Brings Novel Therapeutic Cancer Vaccine to Human Clinical Trials
- A Big Step on the Road to Soft Machines
- ‘Groovy’ hologram creates strange state of light at visible and invisible wavelengths
- Seeing depth through a single lens – Breakthrough Inexpensive 3D
- New coating turns ordinary glass into superglass
- Lifelike cooling for sunbaked windows
- Printing Tiny Batteries
- This Robotic Bee Just Took Flight, To Pollinate Crops And (Maybe) Spy On You
- Robotic insects make first controlled flight
- Robot hands gain a gentler touch
- Rethinking wind power
- Counting the twists in a helical light beam
- Bioinspired fibers change color when stretched
- Prefabricated healing kit: Injectable sponge delivers drugs, cells, and structure
- Tough gel stretches to 21 times its length, recoils, and heals itself
- Flat lens offers a perfect image
- New coating evicts biofilms for good
- Artificial jellyfish created from rat heart tissue and silicone
- In New Mass-Production Technique, Robotic Insects Spring to Life
- Carnivorous Plant Inspires Coating That Resists Just About Any Liquids
- Mobile phones in developing nations could charge up using dirt
Radio is made from atomic-scale defects in diamond
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have made the world’s smallest radio receiver – built out of an assembly of atomic-scale defects in pink diamonds.
This tiny radio — whose building blocks are the size of two atoms — can withstand extremely harsh environments and is biocompatible, meaning it could work anywhere from a probe on Venus to a pacemaker in a human heart.
The radio uses tiny imperfections in diamonds called nitrogen-vacancy (NV) centers. To make NV centers, researchers replace one carbon atom in a tiny diamond crystal with a nitrogen atom and remove a neighboring atom — creating a system that is essentially a nitrogen atom with a hole next to it. NV centers can be used to emit single photons or detect very weak magnetic fields. They have photoluminescent properties, meaning they can convert information into light, making them powerful and promising systems for quantum computing, phontonics and sensing.
Radios have five basic components — a power source, a receiver, a transducer to convert the high-frequency electromagnetic signal in the air to a low-frequency current, speaker or headphones to convert the current to sound and a tuner.
In the Harvard device, electrons in diamond NV centers are powered, or pumped, by green light emitted from a laser. These electrons are sensitive to electromagnetic fields, including the waves used in FM radio. When NV center receives radio waves it converts them and emits the audio signal as red light. A common photodiode converts that light into a current, which is then converted to sound through a simple speaker or headphone.
An electromagnet creates a strong magnetic field around the diamond, which can be used to change the radio station, tuning the receiving frequency of the NV centers.
Shao and Loncar used billions of NV centers in order to boost the signal, but the radio works with a single NV center, emitting one photon at a time, rather than a stream of light.
The radio is extremely resilient, thanks to the inherent strength of diamond. The team successfully played music at 350 degrees Celsius — about 660 Fahrenheit.
“Diamonds have these unique properties,” said Loncar. “This radio would be able to operate in space, in harsh environments and even the human body, as diamonds are biocompatible.”
The planet is warming at an unprecedented rate, and reducing emissions of greenhouse gases alone is not enough to remove the risk.
Last year’s historic Paris climate agreement set the goal of keeping global temperatures no higher than 1.5 degrees Celsius above preindustrial levels. Emission reductions will be central to achieving that goal, but supplemental efforts can further reduce risks.
One drastic idea is solar geoengineering — injecting light-reflecting sulfate aerosols into the stratosphere to cool the planet. Researchers know that large amounts of aerosols can significantly cool the planet; the effect has been observed after large volcanic eruptions. But these sulfate aerosols also carry significant risks. The biggest known risk is that they produce sulfuric acid in the stratosphere, which damages ozone. Since the ozone layer absorbs ultraviolet light from the sun, its depletion can lead to increased rates of skin cancer, eye damage, and other adverse consequences.
Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have identified an aerosol for solar geoengineering that may be able to cool the planet while simultaneously repairing ozone damage.
The research is published in the Proceedings of the National Academy of Sciences.
“In solar geoengineering research, introducing sulfuric acid into the atmosphere has been the only idea that had any serious traction until now,” said David Keith, the Gordon McKay Professor of Applied Physics at SEAS and professor of public policy at the Harvard Kennedy School, the first author of the paper. “This research is a turning point and an important step in analyzing and reducing certain risks of solar geoengineering.”
This research fundamentally rethinks what kinds of particles should be used for solar geoengineering, said Frank Keutsch, the Stonington Professor of Engineering and Atmospheric Science at SEAS and professor of chemistry and chemical biology, a co-author of the paper.
Previous research focused on ways to limit the ozone-damaging reactions produced by nonreactive aerosols. But Keutsch and Keith, along with co-authors Debra Weisenstein and John Dykema, took a completely different approach, targeting aerosols that are highly reactive.
“Anytime you introduce even initially unreactive surfaces into the stratosphere, you get reactions that ultimately result in ozone destruction, as they are coated with sulfuric acid,” said Keutsch. “Instead of trying to minimize the reactivity of the aerosol, we wanted a material that is highly reactive but in a way that would avoid ozone destruction.”
In order to keep aerosols from harming the ozone, the particles would need to neutralize sulfuric, nitric, and hydrochloric acid on their surface. To find such a particle, Keutsch turned to his handy periodic table. After eliminating the toxic elements, the finicky and rare metals, the team was left with the alkali and alkaline Earth metals, which included sodium and calcium carbonate.
“Essentially, we ended up with an antacid for the stratosphere,” said Keutsch.
Through extensive modeling of stratospheric chemistry, the team found that calcite, a constituent of limestone, could counter ozone loss by neutralizing emissions-borne acids in the atmosphere, while also reflecting light and cooling the planet.
“Calcite is one of the most common compounds found in the Earth’s crust,” said Keith. ”The amounts that would be used in a solar geoengineering application are small compared to what’s found in surface dust.”
The researchers have already begun testing calcite in lab experiments that mimic stratospheric conditions. Keith and Keutsch caution that introducing anything into the atmosphere may have unanticipated consequences.
“Stratospheric chemistry is complicated and we don’t understand everything about it,” Keith said. “There are ways that this approach could increase global ozone but at the same time, because of the climate dynamics in the polar regions, increase the ozone hole.”
The researchers emphasize that even if all the attendant risks could be reduced to acceptable levels, solar geoengineering is not a solution to climate change.
“Geoengineering is like taking painkillers,” said Keutsch. “When things are really bad, painkillers can help but they don’t address the cause of a disease and they may cause more harm than good. We really don’t know the effects of geoengineering, but that is why we’re doing this research.”
The research is supported by the Fund for Innovative Climate and Engineering Research and the Star Family Challenge for Promising Scientific Research.
Keith and Keutsch are among several faculty who will be part of the Harvard’s Solar Geoengineering Research Program, a University-wide, interdisciplinary research effort that will be launched in the spring. Housed within the Harvard University Center for the Environment, it will be one of the largest and most visible solar geoengineering research initiatives.
Learn more: Mitigating the risk of geoengineering
Harvard physicists pass spin information through a superconductor
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have made a discovery that could lay the foundation for quantum superconducting devices. Their breakthrough solves one the main challenges to quantum computing: how to transmit spin information through superconducting materials.
Every electronic device — from a supercomputer to a dishwasher — works by controlling the flow of charged electrons. But electrons can carry so much more information than just charge; electrons also spin, like a gyroscope on axis.
Harnessing electron spin is really exciting for quantum information processing because not only can an electron spin up or down — one or zero — but it can also spin any direction between the two poles. Because it follows the rules of quantum mechanics, an electron can occupy all of those positions at once. Imagine the power of a computer that could calculate all of those positions simultaneously.
A whole field of applied physics, called spintronics, focuses on how to harness and measure electron spin and build spin equivalents of electronic gates and circuits.
By using superconducting materials through which electrons can move without any loss of energy, physicists hope to build quantum devices that would require significantly less power.
But there’s a problem.
According to a fundamental property of superconductivity, superconductors can’t transmit spin. Any electron pairs that pass through a superconductor will have the combined spin of zero.
In work published recently in Nature Physics, the Harvard researchers found a way to transmit spin information through superconducting materials.
“We now have a way to control the spin of the transmitted electrons in simple superconducting devices,” said Amir Yacoby, Professor of Physics and of Applied Physics at SEAS and senior author of the paper.
It’s easy to think of superconductors as particle super highways but a better analogy would be a super carpool lane as only paired electrons can move through a superconductor without resistance.
These pairs are called Cooper Pairs and they interact in a very particular way. If the way they move in relation to each other (physicists call this momentum) is symmetric, then the pair’s spin has to be asymmetric — for example, one negative and one positive for a combined spin of zero. When they travel through a conventional superconductor, Cooper Pairs’ momentum has to be zero and their orbit perfectly symmetrical.
But if you can change the momentum to asymmetric — leaning toward one direction — then the spin can be symmetric. To do that, you need the help of some exotic (aka weird) physics.
Superconducting materials can imbue non-superconducting materials with their conductive powers simply by being in close proximity. Using this principle, the researchers built a superconducting sandwich, with superconductors on the outside and mercury telluride in the middle. The atoms in mercury telluride are so heavy and the electrons move so quickly, that the rules of relativity start to apply.
“Because the atoms are so heavy, you have electrons that occupy high-speed orbits,” said Hechen Ren, coauthor of the study and graduate student at SEAS. “When an electron is moving this fast, its electric field turns into a magnetic field which then couples with the spin of the electron. This magnetic field acts on the spin and gives one spin a higher energy than another.”
So, when the Cooper Pairs hit this material, their spin begins to rotate.
“The Cooper Pairs jump into the mercury telluride and they see this strong spin orbit effect and start to couple differently,” said Ren. “The homogenous breed of zero momentum and zero combined spin is still there but now there is also a breed of pairs that gains momentum, breaking the symmetry of the orbit. The most important part of that is that the spin is now free to be something other than zero.”
The team could measure the spin at various points as the electron waves moved through the material. By using an external magnet, the researchers could tune the total spin of the pairs.
“This discovery opens up new possibilities for storing quantum information. Using the underlying physics behind this discovery provides also new possibilities for exploring the underlying nature of superconductivity in novel quantum materials,” said Yacoby.
Learn more: A new spin on superconductivity
Wyss Institute team unveils a low-cost, portable method to manufacture biomolecules for a wide range of vaccines, other therapies as well as diagnostics
Even amidst all the celebrated advances of modern medicine, basic life-saving interventions are still not reaching massive numbers of people who live in our planet’s most remote and non-industrialized locations. The World Health Organization states that one half of the global population lives in rural areas. And according to UNICEF, last year nearly 20 million infants globally did not receive what we would consider to be basic vaccinations required for a child’s health.
These daunting statistics are largely due to the logistical challenge of transporting vaccines and other biomolecules used in diagnostics and therapy, which conventionally require a “cold chain” of refrigeration from the time of synthesis to the time of administration. In remote areas lacking power or established transport routes, modern medicine often cannot reach those who may need it urgently.
A team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering has been working toward a paradigm-shifting goal: a molecular manufacturing method that can produce a broad range of biomolecules, including vaccines, antimicrobial peptides and antibody conjugates, anywhere in the world, without power or refrigeration.
Now, in a new paper published September 22 in Cell journal, the team has unveiled what they set out to deliver, a “just add water” portable method that affordably, rapidly, and precisely generates compounds that could be administered as therapies or used in experiments and diagnostics.
“The ability to synthesize and administer biomolecular compounds, anywhere, could undoubtedly shift the reach of medicine and science across the world,” said Wyss Core Faculty member James Collins, Ph.D., senior author on the study, who is also Professor of Medical Engineering & Science and Professor of Biological Engineering at the Massachusetts Institute of Technology (MIT)’s Department of Biological Engineering. “Our goal is make biomolecular manufacturing accessible wherever it could improve lives.”
The approach, called “portable biomolecular manufacturing” by Collins’ team, which also included Neel Joshi, Ph.D., a Wyss Core Faculty member and Associate Professor of Chemical and Biological Engineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS), hinges on the idea that freeze-dried pellets containing “molecular machinery” can be mixed and matched to achieve a wide variety of end-products. By simply adding water, this molecular machinery can be set in motion.
To activate the biomolecular manufacturing process, freeze-dried components need simply be rehydrated (as seen in this mock demonstration). Credit: Wyss Institute at Harvard University
Compounds manufactured using the method could be administered in several ways to a patient, including injection, oral doses or topical applications. As described in the study, a vaccine against diphtheria was synthesized using the method and shown to successfully induce an antibody response against the pathogen in mice.
Subsequently, the team envisions that the method could be employed to create batches of tetanus or flu shots routinely manufactured in remote clinics. Vaccines against emerging infectious disease outbreaks could quickly be mobilized in the field to contain spiraling epidemics. Episodes of food poisoning could be dosed orally with the production of neutralizing antibodies produced on the spot. Flesh wounds susceptible to infection could be applied with topical antimicrobial peptides generated on demand. In these manners, the team’s approach could be leveraged to design a vast number of different lifesaving measures.
The approach is built upon work described in a seminal 2014 paper also published in Cell, when the team demonstrated that transcription and translation machinery could function in vitro, without being inside living cells, inside freeze-dried slips of ordinary paper embedded with synthetic gene networks.
The Wyss Institute team envisions that the compounds created using the portable manufacturing method could be administered to patients in a variety of ways, including injection (as seen in this mock demonstration), oral delivery, and topical application. Credit: Wyss Institute at Harvard University
Building off that work, the novel manufacturing method employs two types of freeze-dried pellets containing different kinds of components. The first kind of pellet contains the cell-free “machinery” that will synthesize the end product. The second kind contains DNA instructions that will tell the “machinery” what compound to manufacture. When the two types of pellets are combined and rehydrated with water, the biomolecular manufacturing process is triggered. The second type of pellet can be customized to produce a wide range of final products.
Since they are freeze-dried, the pellets are extremely stable and safe for long-term storage at room temperature for up to and potentially beyond one year.
“This approach could — with very little training — put therapeutics and diagnostic tools in the hands of clinicians working in remote areas without power,” said Keith Pardee, Ph.D., a co-first author on the study who was a Wyss Research Scientist and is now an Assistant Professor in the Leslie Dan Faculty of Pharmacy at the University of Toronto. “Currently, distribution of life-saving doses of protein-based preventative and interventional medicines are often restricted by access to an uninterrupted chain of cold refrigeration, which many areas of the world lack.”
The cost of the approach, at roughly three cents per microliter, could also give access to biomolecular manufacturing to researchers and educators who lack access to wet labs and other sophisticated equipment, impacting basic science beyond the immediately apparent promise in clinical applications.
“Synthetic biology has been harnessed to increase efficiency of manufacturing of biological products for medical and energy applications in the past, however, this new breakthrough utterly changes the application landscape,” said Wyss Core Faculty member Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at Harvard’s SEAS. “It’s really exciting because this new biomolecular manufacturing technology potentially offers a way to solve the cold chain problem that still restricts delivery of vaccines and other important medical treatments to patients in the most far-flung corners of the world who need them the most.”
Powered by a chemical reaction controlled by microfluidics, 3D-printed ‘octobot’ has no electronics
A team of Harvard University researchers with expertise in 3D printing, mechanical engineering, and microfluidics has demonstrated the first autonomous, untethered, entirely soft robot. This small, 3D-printed robot — nicknamed the octobot — could pave the way for a new generation of completely soft, autonomous machines.
Soft robotics could revolutionize how humans interact with machines. But researchers have struggled to build entirely compliant robots. Electric power and control systems — such as batteries and circuit boards — are rigid and until now soft-bodied robots have been either tethered to an off-board system or rigged with hard components.
Robert Wood, the Charles River Professor of Engineering and Applied Sciences and Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) led the research. Lewis and Wood are also core faculty members of the Wyss Institute for Biologically Inspired Engineering at Harvard University.
“One long-standing vision for the field of soft robotics has been to create robots that are entirely soft, but the struggle has always been in replacing rigid components like batteries and electronic controls with analogous soft systems and then putting it all together,” said Wood. “This research demonstrates that we can easily manufacture the key components of a simple, entirely soft robot, which lays the foundation for more complex designs.”
The research is described in the journal Nature.
“Through our hybrid assembly approach, we were able to 3D print each of the functional components required within the soft robot body, including the fuel storage, power and actuation, in a rapid manner,” said Lewis. “The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality.”
Octopuses have long been a source of inspiration in soft robotics. These curious creatures can perform incredible feats of strength and dexterity with no internal skeleton.
Harvard’s octobot is pneumatic-based — powered by gas under pressure. A reaction inside the bot transforms a small amount of liquid fuel (hydrogen peroxide) into a large amount of gas, which flows into the octobot’s arms and inflates them like a balloon.
“Fuel sources for soft robots have always relied on some type of rigid components,” said Michael Wehner, a postdoctoral fellow in the Wood lab and co-first author of the paper. “The wonderful thing about hydrogen peroxide is that a simple reaction between the chemical and a catalyst — in this case platinum — allows us to replace rigid power sources.”
To control the reaction, the team used a microfluidic logic circuit based on pioneering work by co-author and chemist George Whitesides, the Woodford L. and Ann A. Flowers University Professor and core faculty member of the Wyss. The circuit, a soft analog of a simple electronic oscillator, controls when hydrogen peroxide decomposes to gas in the octobot.
“The entire system is simple to fabricate, by combining three fabrication methods — soft lithography, molding and 3D printing — we can quickly manufacture these devices,” said Ryan Truby, a graduate student in the Lewis lab and co-first author of the paper.
The simplicity of the assembly process paves the way for more complex designs. Next, the Harvard team hopes to design an octobot that can crawl, swim and interact with its environment.
“This research is a proof of concept,” Truby said. “We hope that our approach for creating autonomous soft robots inspires roboticists, material scientists and researchers focused on advanced manufacturing,”
Learn more: The first autonomous, entirely soft robot
Researchers identify western US counties with the highest risk of exposure to pollution from wildfires
Wildfires threaten more than land and homes. The smoke they produce contains fine particles (PM2.5) that can poison the air for hundreds of miles. Air pollution from the 2016 Fort McMurray fire in northern Alberta, Canada sent people in Michigan to the hospital with respiratory illnesses.
As wildfires increase in frequency and severity due to climate change, more and more communities are at risk of prolonged exposure to harmful levels of smoke.
Harvard University researchers, in collaboration with colleagues at Yale University, have created a watch list of hundreds of counties in the western United States at the highest risk of exposure to dangerous levels of pollution from wildfires in the coming decades.
Among those counties, heavily populated counties such as San Francisco County, CA, King County, WA, Alameda County, CA, and Contra Costa County, CA are estimated to face the highest level of risk of wildfire smoke exposure in the coming decades.
The research is described in the journal Climatic Change.
“It hasn’t been well understood which populations will be most affected by the threat of air pollution from wildfires induced by climate change,” said Loretta J. Mickley, Senior Research Fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and coauthor of the paper. “If we can better predict, down to a county level, who will be most affected, the U.S. Forest Service can prioritize efforts to reduce wildfire risk, such as setting prescribed fires to clear out dry underbrush.”
To identify the highest-risk areas, the team used a fire prediction model and advanced atmospheric modeling to separate pollution caused by wildfires from other pollution sources and track the likely movement of smoke. The team coined a new term, ‘smoke wave,’ to describe two or more consecutive days of unhealthy levels of PM2.5 from fires.
The study found that across the western U.S., climate change will likely cause smoke waves to be longer, more intense, and more frequent. Of the 561 counties studied, 312 are expected to have more intense smoke waves in the next 30 years.
The team found that between 2004 and 2009, about 57 million people in the western U.S. experienced a smoke wave. Between 2046 and 2051, the team estimated more than 82 million people will likely to be affected by smoke waves, mostly in Northern California, Western Oregon and the Great Plains, where fire fuel is plentiful.
The team estimated that about 13 million more children and seniors — who are at higher risk for respiratory illness — will be affected by smoke waves compared with the present day.
“In the coming decades, we will be seeing the significant human health consequences from these extreme events in a changing climate,” said Jia Coco Liu, a recent Ph.D. graduate at the Yale School of Forestry and Environmental Studies and first author of the paper.
But it’s not just the future that worries health officials.
“Climate change is a public health crisis and it’s happening right now,” said Francesca Dominici, Professor of Biostatistics and Senior Associate Dean for Research at the Harvard T.H. Chan School of Public Health and coauthor of the paper. “Asthmatic kids are going to the hospital today in California because of the smoke from wildfires. If we can figure out who is most at risk, we can start thinking about smoke evacuations and early alert systems for hospitals and local primary care physicians.”
Soft materials are great at damping energy — that’s why rubber tires are so good at absorbing the shock of bumps and potholes. But if researchers are going to build autonomous soft systems, like soft robots, they’ll need a way to transmit energy through soft materials.
Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with colleagues at the California Institute of Technology, have developed a way to send mechanical signals through soft materials.
The research is described in the Proceedings of the National Academy of Sciences.
“Soft autonomous systems have received a lot of attention because, just like the human body or other biological systems, they can be adaptive and perform delicate movements. However, the highly dissipative nature of soft materials limits or altogether prevents certain functions,” said Jordan Raney, postdoctoral fellow at SEAS and first author of the paper. “By storing energy in the architecture itself we can make up for the energy losses due to dissipation, allowing the propagation of mechanical signals across long distances.”
The system uses the centuries-old concept of bistable beams — structures stable in two distinct state — to store and release elastic energy along the path of a wave. The system consists of a chain of bistable elastomeric beams connected by elastomeric linear springs. When those beams are deformed, they snap and store energy in the form of elastic deformation. As the signal moves down the elastomer, it snaps the beams back into place, releasing the stored energy and sending the signal downstream like a line of dominos. The bistable system prevents the signal from dissipating downstream.
“This design solves two fundamental problems in transmitting information through materials,” said Katia Bertoldi, the John L. Loeb Associate Professor of the Natural Sciences at SEAS and senior author of the paper. “It not only overcomes dissipation, but it also eliminates dispersive effects, so that the signal propagates without distortion. As such, we maintain signal strength and clarity from start to end.”
The beam geometry requires precise fabrication techniques. If the angle or thickness of one beam is off by one degree or millimeter, the whole system fails.
The team used advanced 3D printing techniques to fabricate the system.
“We’re developing new materials and printing methods that enable the fabrication of soft materials with programmable bistable elements,” said Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering and coauthor of the paper.
The team designed and printed a soft logic gate using this system. The gate, which looks like a tuning fork, can be controlled to act as either as an AND or as an OR gate.
“It’s amazing what you can do using simple beams — a building block that’s been around hundreds of years,” said Bertoldi. “You can do new stuff with a very old, well studied and very simple component.”
Learn more: Transmitting energy in soft materials
New molecules promise cheaper, more efficient OLED displays
Harvard University researchers have designed more than 1,000 new blue-light emitting molecules for organic light-emitting diodes (OLEDs) that could dramatically improve displays for televisions, phones, tablets and more.
OLED screens use organic molecules that emit light when an electric current is applied. Unlike ubiquitous liquid crystal displays (LCDs), OLED screens don’t require a backlight, meaning the display can be as thin and flexible as a sheet of plastic. Individual pixels can be switched on or entirely off, dramatically improving the screen’s color contrast and energy consumption. OLEDs are already replacing LCDs in high-end consumer devices but a lack of stable and efficient blue materials has made them less competitive in large displays such as televisions.
The interdisciplinary team of Harvard researchers, in collaboration with MIT and Samsung, developed a large-scale, computer-driven screening process, called the Molecular Space Shuttle, that incorporates theoretical and experimental chemistry, machine learning and cheminformatics to quickly identify new OLED molecules that perform as well as, or better than, industry standards.
“People once believed that this family of organic light-emitting molecules was restricted to a small region of molecular space,” said Alán Aspuru-Guzik, Professor of Chemistry and Chemical Biology, who led the research. “But by developing a sophisticated molecular builder, using state-of-the art machine learning, and drawing on the expertise of experimentalists, we discovered a large set of high-performing blue OLED materials.”
The research is described in the current issue of Nature Materials.
The biggest challenge in manufacturing affordable OLEDs is emission of the color blue.
Like LCDs, OLEDs rely on green, red and blue subpixels to produce every color on screen. But it has been difficult to find organic molecules that efficiently emit blue light. To improve efficiency, OLED producers have created organometallic molecules with expensive transition metals like iridium to enhance the molecule through phosphorescence. This solution is expensive and it has yet to achieve a stable blue color.
Aspuru-Guzik and his team sought to replace these organometallic systems with entirely organic molecules.
The team began by building libraries of more than 1.6 million candidate molecules. Then, to narrow the field, a team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), led by Ryan Adams, Assistant Professor of Computer Science, developed new machine learning algorithms to predict which molecules were likely to have good outcomes, and prioritize those to be virtually tested. This effectively reduced the computational cost of the search by at least a factor of ten.
“This was a natural collaboration between chemistry and machine learning,” said David Duvenaud, a postdoctoral fellow in the Adams lab and coauthor of the paper. “Since the early stages of our chemical design process starts with millions of possible candidates, there’s no way for a human to evaluate and prioritize all of them. So, we used neural networks to quickly prioritize the candidates based on all the molecules already evaluated.”
“Machine learning tools are really coming of age and starting to see applications in a lot of scientific domains,” said Adams. “This collaboration was a wonderful opportunity to push the state of the art in computer science, while also developing completely new materials with many practical applications. It was incredibly rewarding to see these designs go from machine learning predictions to devices that you can hold in your hand.”
“We were able to model these molecules in a way that was really predictive,” said Rafael Gómez-Bombarelli, a postdoctoral fellow in the Aspuru-Guzik lab and first author of the paper. “We could predict the color and the brightness of the molecules from a simple quantum chemical calculation and about 12 hours of computing per molecule. We were charting chemical space and finding the frontier of what a molecule can do by running virtual experiments.”
“Molecules are like athletes,” Aspuru-Guzik said. “It’s easy to find a runner, it’s easy to find a swimmer, it’s easy to find a cyclist but it’s hard to find all three. Our molecules have to be triathletes. They have to be blue, stable and bright.”
But finding these super molecules takes more than computing power — it takes human intuition, said Tim Hirzel, a senior software engineer in the Department of Chemistry and Chemical Biology and coauthor of the paper.
To help bridge the gap between theoretical modeling and experimental practice, Hirzel and the team built a web application for collaborators to explore the results of more than half a million quantum chemistry simulations.
Every month, Gómez-Bombarelli and coauthor Jorge Aguilera-Iparraguirre, also a postdoctoral fellow in the Aspuru-Guzik lab, selected the most promising molecules and used their software to create “baseball cards,” profiles containing important information about each molecule. This process identified 2500 molecules worth a closer look. The team’s experimental collaborators at Samsung and MIT then voted on which molecules were most promising for application. The team nicknamed the voting tool “molecular Tinder” after the popular online dating app.
“We facilitated the social aspect of the science in a very deliberate way,” said Hirzel.
“The computer models do a lot but the spark of genius is still coming from people,” said Gómez-Bombarelli.
“The success of this effort stems from its multidisciplinary nature,” said Aspuru-Guzik. “Our collaborators at MIT and Samsung provided critical feedback regarding the requirements for the molecular structures.”
“The high throughput screening technique pioneered by the Harvard team significantly reduced the need for synthesis, experimental characterization, and optimization,” said Marc Baldo, Professor of Electrical Engineering and Computer Science at MIT and coauthor of the paper. “It shows the industry how to advance OLED technology faster and more efficiently.”
After this accelerated design cycle, the team was left with hundreds of molecules that perform as well as, if not better than, state-of-the-art metal-free OLEDs.
Applications of this type of molecular screening also extend far beyond OLEDs.
“This research is an intermediate stop in a trajectory towards more and more advanced organic molecules that could be used in flow batteries, solar cells, organic lasers, and more,” said Aspuru-Guzik. “The future of accelerated molecular design is really, really exciting.”
Learn more: Towards a better screen
Soft actuator could be ‘holy grail’ for soft robotics
Soft robots do a lot of things well but they’re not exactly known for their speed. The artificial muscles that move soft robots, called actuators, tend to rely on hydraulics or pneumatics, which are slow to respond and difficult to store.
Dielectric elastomers, soft materials that have good insulating properties, could offer an alternative to pneumatic actuators but they currently require complex and inefficient circuitry to deliver high voltage as well as rigid components to maintain their form— both of which defeat the purpose of a soft robot.
Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a dielectric elastomer with a broad range of motion that requires relatively low voltage and no rigid components.
They published their work recently in Advanced Materials.
“We think this has the potential to be the holy grail of soft robotics,” said Mishu Duduta, a graduate student at SEAS and first author of the paper. “Electricity is easy to store and deliver but until now, the electric fields required to power actuators in soft robots has been too high. This research solves a lot of the challenges in soft actuation by reducing actuation voltage and increasing energy density, while eliminating rigid components.”
Research opens a ‘new universe’ of organic molecules that can store energy in flow batteries
Harvard researchers have identified a whole new class of high-performing organic molecules, inspired by vitamin B2, that can safely store electricity from intermittent energy sources like solar and wind power in large batteries.
The development builds on previous work in which the team developed a high-capacity flow battery that stored energy in organic molecules called quinones and a food additive called ferrocyanide. That advance was a game-changer, delivering the first high-performance, non-flammable, non-toxic, non-corrosive, and low-cost chemicals that could enable large-scale, inexpensive electricity storage.
While the versatile quinones show great promise for flow batteries, Harvard researchers continued to explore other organic molecules in pursuit of even better performance. But finding that same versatility in other organic systems has been challenging.
“Now, after considering about a million different quinones, we have developed a new class of battery electrolyte material that expands the possibilities of what we can do,” said Kaixiang Lin, a Ph.D. student at Harvard and first author of the paper. “Its simple synthesis means it should be manufacturable on a large scale at a very low cost, which is an important goal of this project.”