Representing the battery breakthrough that is ready to commercialize and promises much more battery capacity for our smartphones and electric vehicles and extremely fast charging. So, the price of electric vehicles will be very close and even lower than conventional gasoline-powered vehicles very soon to provide a clean and quiet future.
IMAGE: NOVEL NANOLASER LEVERAGES THE SAME COLOR-CHANGING MECHANISM THAT A CHAMELEON USES TO CAMOUFLAGE ITS SKIN.
As a chameleon shifts its color from turquoise to pink to orange to green, nature’s design principles are at play. Complex nano-mechanics are quietly and effortlessly working to camouflage the lizard’s skin to match its environment.
Bonus: The Electric Vehicle Disruption – The End of Oil by 2030
SolarEdge Technologies is unveiling its residential electric vehicle charging station at Intersolar Europe. Following the recent debut of its EV-charging single-phase inverter, SolarEdge will now also provide a standalone EV charger that offers greater system design flexibility, specifically for sites where the inverter and EV charger cannot be installed at the same location.
The new EV charger will be integrated into SolarEdge’s smart energy suite to support increased energy independence. With the EV charger offering management in SolarEdge’s monitoring platform, EV charging can be easily controlled and programmed. 
“This EV charger reflects our ongoing commitment to develop smart energy solutions to improve the ways we produce and consume energy,” said Lior Handelsman, VP of marketing and product strategy of SolarEdge, and founder. “With the EV and PV markets having significant overlap, SolarEdge believes that combining the two solutions will accelerate the adoption of both technologies and give individuals more control over their energy usage, thus reducing their carbon footprint.”
Green and renewable energy markets are bringing power to millions with virtually no adverse environmental impacts, but before we can count on renewables for widespread reliability, one critical innovation must arrive: storage.
PetersenDean Inc. employees install solar panels on the roof of a home in Lafayette, California, U.S., Photographer: David Paul Morris/Bloomberg
On Tuesday, May 15, 2018. California became the first state in the U.S. to require solar panels on almost all new homes. Most new units built after Jan. 1, 2020, will be required to include solar systems as part of the standards adopted by the California Energy Commission.
While hydroelectric and some other renewable sources can generate power around the clock, solar and wind energy are irregular and not necessarily consistent sources for 24/7 projections.
Storms and darkness disrupt solar farms, while dozens of meteorological phenomena can impact wind farms. Because these sources have natural peaks, they cannot be made to align with consumer power demand without effective storage. Solar and wind may be able to meet demand during the day or a short period, but when energy is high and demand is low, the power generated must either be used or wasted if it cannot be stored in some type of battery.
According to projections from GTM Research and the Energy Storage Association, the energy storage market is expected to grow 17x from 2017 and 2023. This projection accounts for private and commercial deployment of storage capacity, including impacts from government policies like California’s solar panel mandate.
During the same interval, the energy storage market is expected to grow 14x in dollar value.
The exact type of storage deployments in these projections varies. Recent innovations have included advancements in traditional battery technology as well as battery alternatives like liquid air storage.
In New York, one project included a megawatt scaled lithium-ion battery storage system to replace lead acid schemes. The liquid air storage, however, uses excess energy to cool air in pressurized chambers until it is liquid. Rather than storing electrical or chemical energy like a battery, the process stores potential energy.
When demand arises, the liquefied air is allowed to rapidly heat and expand, turning turbines to generate electricity.
Meanwhile, Tesla has added nearly a third of the annual global energy storage deployments since 2015. Leading the charge with low-cost lithium-ion batteries, Telsla and other innovators are bringing global capacity up quickly.
These energy storage devices are versatile, capable of storing energy from any source–fossil fuel or renewable– and in any place–private homes or industrial operations.
With battery costs continuing to decrease and battery alternatives coming into the fore, projections of storage capacity are indeed quite possible. Assuming the electric industry can indeed upgrade its current infrastructure, new grid connections means that energy will be able to be shared more than ever, perhaps even traveling far distances during peak or be stored for non-peak use anywhere on the grid.
When storage costs and capacity align with market incentives, we may just see a renewable energy revolution, one that makes distributed generation mainstream for all consumers.
** Contributed from Forbes Energy
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04.
Energy Storage
Industry veterans from Tesla, Aquion and A123 are trying to create cost-effective energy storage to last for weeks and months.
A crew of battle-tested cleantech veterans raised serious cash to solve the thorniest problem in clean energy.
As wind and solar power supply more and more of the grid’s electricity, seasonal swings in production become a bigger obstacle. A low- or no-carbon electricity system needs a way to dispatch clean energy on demand, even when wind and solar aren’t producing at their peaks.
Four-hour lithium-ion batteries can help on a given day, but energy storage for weeks or months has yet to arrive at scale.
Into the arena steps Form Energy, a new startup whose founders hope for commercialization not in a couple of years, but in the next decade.
More surprising, they’ve secured $9 million in Series A funding from investors who are happy to wait that long. The funders include both a major oil company and an international consortium dedicated to stopping climate change.
“Renewables have already gotten cheap,” said co-founder Ted Wiley, who worked at saltwater battery company Aquion prior to its bankruptcy. “They are cheaper than thermal generation. In order to foster a change, they need to be just as dependable and just as reliable as the alternative. Only long-duration storage can make that happen.”
It’s hard to overstate just how difficult it will be to deliver.
The members of Form will have to make up the playbook as they go along. The founders, though, have a clear-eyed view of the immense risks. They’ve systematically identified materials that they think can work, and they have a strategy for proving them out.
Wiley and Mateo Jaramillo, who built the energy storage business at Tesla, detailed their plans in an exclusive interview with Greentech Media, describing the pathway to weeks- and months-long energy storage and how it would reorient the entirety of the grid.
The team
Form Energy tackles its improbable mission with a team of founders who have already made their mark on the storage industry, and learned from its most notable failures.
There’s Jaramillo, the former theology student who built the world’s most recognizable stationary storage brand at Tesla before stepping away in late 2016. Soon after, he started work on the unsolved long-duration storage problem with a venture he called Verse Energy.
Separately, MIT professor Yet-Ming Chiang set his sights on the same problem with a new venture, Baseload Renewables. His battery patents made their mark on the industry and launched A123 and 24M. More recently, he’d been working with the Department of Energy’s Joint Center on Energy Storage Research on an aqueous sulfur formula for cost-effective long-duration flow batteries.
He brought on Wiley, who had helped found Aquion and served as vice president of product and corporate strategy before he stepped away in 2015. Measured in real deployments, Aquion led the pack of long-duration storage companies until it suddenly went bankrupt in March 2017.
Chiang and Wiley focused on storing electricity for days to weeks; Jaramillo was looking at weeks to months. MIT’s “tough tech” incubator The Engine put in $2 million in seed funding, while Jaramillo had secured a term sheet of his own. In an unusual move, they elected to join forces rather than compete.
Rounding out the team are Marco Ferrara, the lead storage modeler at IHI who holds two Ph.D.s; and Billy Woodford, an MIT-trained battery scientist and former student of Chiang’s.
The product
Form doesn’t think of itself as a battery company.
It wants to build what Jaramillo calls a “bidirectional power plant,” one which produces renewable energy and delivers it precisely when it is needed. This would create a new class of energy resource: “deterministic renewables.”
By making renewable energy dispatchable throughout the year, this resource could replace the mid-range and baseload power plants that currently burn fossil fuels to supply the grid.
Without such a tool, transitioning to high levels of renewables creates problems.
Countries could overbuild their renewable generation to ensure that the lowest production days still meet demand, but that imposes huge costs and redundancies. One famous 100 percent renewables scenario notoriously relied on a 15x increase in U.S. hydropower capacity to balance the grid in the winter.
The founders are remaining coy about the details of the technology itself.
Jaramillo and Wiley confirmed that both products in development use electrochemical energy storage. The one Chiang started developing uses aqueous sulfur, chosen for its abundance and cheap price relative to its storage ability. Jaramillo has not specified what he chose for seasonal storage.
What I did confirm is that they have been studying all the known materials that can store electricity, and crossing off the ones that definitely won’t work for long duration based on factors like abundance and fundamental cost per embodied energy.
“Because we’ve done the work looking at all the options in the electrochemical set, you can positively prove that almost all of them will not work,” Jaramillo said. “We haven’t been able to prove that these won’t work.”
The company has small-scale prototypes in the lab, but needs to prove that they can scale up to a power plant that’s not wildly expensive. It’s one thing to store energy for months, it’s another to do so at a cost that’s radically lower than currently available products.
“We can’t sit here and tell you exactly what the business model is, but we know that we’re engaged with the right folks to figure out what it is, assuming the technical work is successful,” Jaramillo said.
Given the diversity of power markets around the world, there likely won’t be one single business model.
The bidirectional power plant may bid in just like gas plants do today, but the dynamics of charging up on renewable energy could alter the way it engages with traditional power markets. Then again, power markets themselves could look very different by that time.
If the team can characterize a business case for the technology, the next step will be developing a full-scale pilot. If that works, full deployment comes next.
But don’t bank on that happening in a jiffy.
“It’s a decade-long project,” Jaramillo said. “The first half of that is spent on developing things and the second half is hopefully spent deploying things.”
The backer says
The Form founders had to find financial backers who were comfortable chasing a market that doesn’t exist with a product that won’t arrive for up to a decade.
That would have made for a dubious proposition for cleantech VCs a couple of years ago, but the funding landscape has shifted.
The Engine, an offshoot of MIT, started in 2016 to commercialize “tough tech” with long-term capital.
“We’re here for the long shots, the unimaginable, and the unbelievable,” its website proclaims. That group funded Baseload Renewables with $2 million before it merged into Form.
Breakthrough Energy Ventures, the entity Bill Gates launched to provide “patient, risk-tolerant capital” for clean energy game-changers, joined for the Series A.
San Francisco venture capital firm Prelude Ventures joined as well. It previously bet on next-gen battery companies like the secretive QuantumScape and Natron Energy.
The round also included infrastructure firm Macquarie Capital, which has shown an interest in owning clean energy assets for the long haul.
Saudi Aramco, one of the largest oil and gas supermajors in the world, is another backer.
Saudi Arabia happens to produce more sulfur than most other countries, as a byproduct of its petrochemical industry.
While the kingdom relies on oil revenues currently, the leadership has committed to investing billions of dollars in clean energy as a way to scope out a more sustainable energy economy.
“It’s very much consistent with all of the oil supermajors taking a hard look at what the future is,” Jaramillo said. “That entire sector is starting to look beyond petrochemicals.”
Indeed, oil majors have emerged as a leading source of cleantech investment in recent months.
BP re-entered the solar industry with a $200 million investment in developer Lightsource. Total made the largest battery acquisition in history when it bought Saft in 2016; it also has a controlling stake in SunPower. Shell has ramped up investments in distributed energy, including the underappreciated thermal energy storage subsegment.
The $9 million won’t put much steel in the ground, but it’s enough to fund the preliminary work refining the technology.
“We would like to come out of this round with a clear understanding of the market need and a clear understanding of exactly how our technology meets the market need,” Wiley said.
The many paths to failure
Throughout the conversation, Jaramillo and Wiley avoided the splashy rhetoric one often hears from new startups intent on saving the world.
Instead, they acknowledge that the project could fail for a multitude of reasons. Here are just a few possibilities:
• The technologies don’t achieve radically lower cost.
• They can’t last for the 20- to 25-year lifetime expected of infrastructural assets.
• Power markets don’t allow this type of asset to be compensated.
• Financiers don’t consider the product bankable.
• Societies build a lot more transmission lines.
• Carbon capture technology removes the greenhouse gases from conventional generation.
• Small modular nuclear plants get permitting, providing zero-carbon energy on demand.
• The elusive hydrogen economy materializes.
Those last few scenarios face problems of their own. Transmission lines cost billions of dollars and provoke fierce local opposition.
Carbon capture technology hasn’t worked economically yet, although many are trying.
Small modular reactors face years of scrutiny before they can even get permission to operate in the U.S.
The costliness of hydrogen has thwarted wide-scale adoption.
One thing the Form Energy founders are not worried about is that lithium-ion makes an end run around their technology on price. That tripped up the initial wave of flow batteries, Wiley noted.
“By the time they were technically mature enough to be deployed, lithium-ion had declined in price to be at or below the price that they could deploy at,” he said.
Those early flow batteries, though, weren’t delivering much longer duration than commercially available lithium-ion. When the storage has to last for weeks or months, the cost of lithium-ion components alone makes it prohibitive.
“Our view is, just from a chemical standpoint, [lithium-ion] is not capable of declining another order of magnitude, but there does seem to be a need for storage that is an order of magnitude cheaper and an order of magnitude longer in duration than is currently being deployed,” Wiley explained.
They also plan to avoid a scenario that helped bring down many a storage startup, Aquion and A123 included: investing lots of capital in a factory before the market had arrived.
Form Energy isn’t building small commoditized products; it’s constructing a power plant.
“When we say we’re building infrastructure, we mean that this is intended to be infrastructure,” Wiley said.
So far, at least, there isn’t much competition to speak of in the super-long duration battery market.
That could start to change. Now that brand-name investors have gotten involved, others are sure to take notice. The Department of Energy launched its own long-duration storage funding opportunity in May, targeting the 10- to 100-hour range.
It may be years before Form’s investigations produce results, if they ever do.
But the company has already succeeded in expanding the realm of what’s plausible and fundable in the energy storage industry.
* From Greentech Media J. Spector
A biomimetic nanosystem can deliver therapeutic proteins to selectively target cancerous tumors, according to a team of Penn State researchers. Using a protein toxin called gelonin from a plant found in the Himalayan mountains, the researchers caged the proteins in self-assembled metal-organic framework (MOF) nanoparticles to protect them from the body’s immune system. To enhance the longevity of the drug in the bloodstream and to selectively target the tumor, the team cloaked the MOF in a coating made from cells from the tumor itself.
Blood is a hostile environment for drug delivery. The body’s immune system attacks alien molecules or else flushes them out of the body through the spleen or liver. But cells, including cancer cells, release small particles called extracellular vesicles that communicate with other cells in the body and send a “don’t eat me” signal to the immune system.
“We designed a strategy to take advantage of the extracellular vesicles derived from tumor cells,” said Siyang Zheng, associate professor of biomedical and electrical engineering at Penn State. “We remove 99 percent of the contents of these extracellular vesicles and then use the membrane to wrap our metal-organic framework nanoparticles. If we can get our extracellular vesicles from the patient, through biopsy or surgery, then the nanoparticles will seek out the tumor through a process called homotypic targeting.”
Gong Cheng, lead author on a new paper describing the team’s work and a former post-doctoral scholar in Zheng’s group now at Harvard, said, “MOF is a class of crystalline materials assembled by metal nodes and organic linkers. In our design, self-assembly of MOF nanoparticles and encapsulation of proteins are achieved simultaneously through a one-pot approach in aqueous environment. The enriched metal affinity sites on MOF surfaces act like the buttonhook, so the extracellular vesicle membrane can be easily buckled on the MOF nanoparticles. Our biomimetic strategy makes the synthetic nanoparticles look like extracellular vesicles, but they have the desired cargo inside.”
The nanoparticle system circulates in the bloodstream until it finds the tumor and locks on to the cell membrane. The cancer cell ingests the nanoparticle in a process called endocytosis. Once inside the cell, the higher acidity of the cancer cell’s intracellular transport vesicles causes the metal-organic framework nanoparticles to break apart and release the toxic protein into cytosol and kill the cell.
“Our metal-organic framework has very high loading capacity, so we don’t need to use a lot of the particles and that keeps the general toxicity low,” Zheng said.
The researchers studied the effectiveness of the nanosystem and its toxicity in a small animal model and reported their findings in a cover article in the Journal of the American Chemical Society.
The researchers believe their nanosystem provides a tool for the targeted delivery of other proteins that require cloaking from the immune system. Penn State has applied for patent protection for the technology.
Story Source:
Materials provided by Penn State. Original written by Walt Mills. Note: Content may be edited for style and length.
A team of material researchers has succeeded in producing a composite material that is particularly suited for electrodes in lithium batteries. The nanocomposite material might help to significantly increase the storage capacity and lifetime of batteries as well as their charging speed.
Lithium-ion batteries are the ultimate benchmark when it comes to mobile phones, tablet devices, and electric cars. Their storage capacity and power density are far superior to other rechargeable battery systems. Despite all the progress that has been made, however, smartphone batteries only last a day and electric cars need hours to be recharged. Scientists are therefore working on ways to improve the power densities and charging rates of all-round batteries. “An important factor is the anode material,” explains Dina Fattakhova-Rohlfing from the Institute of Energy and Climate Research (IEK-1).
“In principle, anodes based on tin dioxide can achieve much higher specific capacities, and therefore store more energy, than the carbon anodes currently being used. They have the ability to absorb more lithium ions,” says Fattakhova-Rohlfing. “Pure tin oxide, however, exhibits very weak cycle stability — the storage capability of the batteries steadily decreases and they can only be recharged a few times. The volume of the anode changes with each charging and discharging cycle, which leads to it crumbling.”
One way of addressing this problem is hybrid materials or nanocomposites — composite materials that contain nanoparticles. The scientists developed a material comprising tin oxide nanoparticles enriched with antimony, on a base layer of graphene. The graphene basis aids the structural stability and conductivity of the material. The tin oxide particles are less than three nanometres in size — in other words less than three millionths of a millimetre — and are directly “grown” on the graphene. The small size of the particle and its good contact with the graphene layer also improves its tolerance to volume changes — the lithium cell becomes more stable and lasts longer. 
Three times more energy in one hour
“Enriching the nanoparticles with antimony ensures the material is extremely conductive,” explains Fattakhova-Rohlfing. “This makes the anode much quicker, meaning that it can store one-and-a-half times more energy in just one minute than would be possible with conventional graphite anodes. It can even store three times more energy for the usual charging time of one hour.”
“Such high energy densities were only previously achieved with low charging rates,” says Fattakhova-Rohlfing. “Faster charging cycles always led to a quick reduction in capacity.” The antimony-doped anodes developed by the scientists, however, retain 77 % of their original capacity even after 1,000 cycles.
“The nanocomposite anodes can be produced in an easy and cost-effective way. And the applied concepts can also be used for the design of other anode materials for lithium-ion batteries,” explains Fattakhova-Rohlfing. “We hope that our development will pave the way for lithium-ion batteries with a significantly increased energy density and very short charging time.”
Story Source:
Materials provided by Forschungszentrum Juelich. Note: Content may be edited for style and length.
Journal Reference:
MIT researchers developed a transmitter that frequency hops data bits ultrafast to prevent signal jamming on wireless devices. The transmitter’s design (pictured) features bulk acoustic wave resonators (side boxes) that rapidly switch between radio frequency channels, sending data bits with each hop. A channel generator (top box) each microsecond selects the random channels to send bits. Two transmitters work in alternating paths (center boxes), so one receives channel selection, while the other sends data, to ensure ultrafast speeds. Courtesy of the researchers
Today, more than 8 billion devices are connected around the world, forming an “internet of things” that includes medical devices, wearables, vehicles, and smart household and city technologies. By 2020, experts estimate that number will rise to more than 20 billion devices, all uploading and sharing data online.
But those devices are vulnerable to hacker attacks that locate, intercept, and overwrite the data, jamming signals and generally wreaking havoc. One method to protect the data is called “frequency hopping,” which sends each data packet, containing thousands of individual bits, on a random, unique radio frequency (RF) channel, so hackers can’t pin down any given packet. Hopping large packets, however, is just slow enough that hackers can still pull off an attack.
Now MIT researchers have developed a novel transmitter that frequency hops each individual 1 or 0 bit of a data packet, every microsecond, which is fast enough to thwart even the quickest hackers.
The transmitter leverages frequency-agile devices called bulk acoustic wave (BAW) resonators and rapidly switches between a wide range of RF channels, sending information for a data bit with each hop. In addition, the researchers incorporated a channel generator that, each microsecond, selects the random channel to send each bit. On top of that, the researchers developed a wireless protocol — different from the protocol used today — to support the ultrafast frequency hopping.
“With the current existing [transmitter] architecture, you wouldn’t be able to hop data bits at that speed with low power,” says Rabia Tugce Yazicigil, a postdoc in the Department of Electrical Engineering and Computer Science and first author on a paper describing the transmitter, which is being presented at the IEEE Radio Frequency Integrated Circuits Symposium. “By developing this protocol and radio frequency architecture together, we offer physical-layer security for connectivity of everything.” Initially, this could mean securing smart meters that read home utilities, control heating, or monitor the grid.
“More seriously, perhaps, the transmitter could help secure medical devices, such as insulin pumps and pacemakers, that could be attacked if a hacker wants to harm someone,” Yazicigil says. “When people start corrupting the messages [of these devices] it starts affecting people’s lives.”
Co-authors on the paper are Anantha P. Chandrakasan, dean of MIT’s School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science (EECS); former MIT postdoc Phillip Nadeau; former MIT undergraduate student Daniel Richman; EECS graduate student Chiraag Juvekar; and visiting research student Kapil Vaidya.
Ultrafast frequency hopping
One particularly sneaky attack on wireless devices is called selective jamming, where a hacker intercepts and corrupts data packets transmitting from a single device but leaves all other nearby devices unscathed. Such targeted attacks are difficult to identify, as they’re often mistaken for poor a wireless link and are difficult to combat with current packet-level frequency-hopping transmitters.
With frequency hopping, a transmitter sends data on various channels, based on a predetermined sequence shared with the receiver. Packet-level frequency hopping sends one data packet at a time, on a single 1-megahertz channel, across a range of 80 channels. A packet takes around 612 microseconds for BLE-type transmitters to send on that channel. But attackers can locate the channel during the first 1 microsecond and then jam the packet.
“Because the packet stays in the channel for long time, and the attacker only needs a microsecond to identify the frequency, the attacker has enough time to overwrite the data in the remainder of packet,” Yazicigil says.
To build their ultrafast frequency-hopping method, the researchers first replaced a crystal oscillator — which vibrates to create an electrical signal — with an oscillator based on a BAW resonator. However, the BAW resonators only cover about 4 to 5 megahertz of frequency channels, falling far short of the 80-megahertz range available in the 2.4-gigahertz band designated for wireless communication. Continuing recent work on BAW resonators — in a 2017 paper co-authored by Chandrakasan, Nadeau, and Yazicigil — the researchers incorporated components that divide an input frequency into multiple frequencies. An additional mixer component combines the divided frequencies with the BAW’s radio frequencies to create a host of new radio frequencies that can span about 80 channels.
Randomizing everything
The next step was randomizing how the data is sent. In traditional modulation schemes, when a transmitter sends data on a channel, that channel will display an offset — a slight deviation in frequency. With BLE modulations, that offset is always a fixed 250 kilohertz for a 1 bit and a fixed -250 kilohertz for a 0 bit. A receiver simply notes the channel’s 250-kilohertz or -250-kilohertz offset as each bit is sent and decodes the corresponding bits.
But that means, if hackers can pinpoint the carrier frequency, they too have access to that information. If hackers can see a 250-kilohertz offset on, say, channel 14, they’ll know that’s an incoming 1 and begin messing with the rest of the data packet.
To combat that, the researchers employed a system that each microsecond generates a pair of separate channels across the 80-channel spectrum. Based on a preshared secret key with the transmitter, the receiver does some calculations to designate one channel to carry a 1 bit and the other to carry a 0 bit. But the channel carrying the desired bit will always display more energy. The receiver then compares the energy in those two channels, notes which one has a higher energy, and decodes for the bit sent on that channel.
For example, by using the preshared key, the receiver will calculate that 1 will be sent on channel 14 and a 0 will be sent on channel 31 for one hop. But the transmitter only wants the receiver to decode a 1. The transmitter will send a 1 on channel 14, and send nothing on channel 31. The receiver sees channel 14 has a higher energy and, knowing that’s a 1-bit channel, decodes a 1. In the next microsecond, the transmitter selects two more random channels for the next bit and repeats the process.
Because the channel selection is quick and random, and there is no fixed frequency offset, a hacker can never tell which bit is going to which channel. “For an attacker, that means they can’t do any better than random guessing, making selective jamming infeasible,” Yazicigil says.
As a final innovation, the researchers integrated two transmitter paths into a time-interleaved architecture. This allows the inactive transmitter to receive the selected next channel, while the active transmitter sends data on the current channel. Then, the workload alternates. Doing so ensures a 1-microsecond frequency-hop rate and, in turn, preserves the 1-megabyte-per-second data rate similar to BLE-type transmitters.
“Most of the current vulnerability [to signal jamming] stems from the fact that transmitters hop slowly and dwell on a channel for several consecutive bits. Bit-level frequency hopping makes it very hard to detect and selectively jam the wireless link,” says Peter Kinget, a professor of electrical engineering and chair of the department at Columbia University. “This innovation was only possible by working across the various layers in the communication stack requiring new circuits, architectures, and protocols. It has the potential to address key security challenges in IoT devices across industries.”
The work was supported by Hong Kong Innovation and Technology Fund, the National Science Foundation, and Texas Instruments. The chip fabrication was supported by TSMC University Shuttle Program.
MIT researchers are developing RFID stickers that sense their environment, enabling low-cost monitoring of chemicals and other signals in the environment Image: Chelsea Turner, MIT
These days, many retailers and manufacturers are tracking their products using RFID, or radio-frequency identification tags. Often, these tags come in the form of paper-based labels outfitted with a simple antenna and memory chip. When slapped on a milk carton or jacket collar, RFID tags act as smart signatures, transmitting information to a radio-frequency reader about the identity, state, or location of a given product.
In addition to keeping tabs on products throughout a supply chain, RFID tags are used to trace everything from casino chips and cattle to amusement park visitors and marathon runners.
The Auto-ID Lab at MIT has long been at the forefront of developing RFID technology. Now engineers in this group are flipping the technology toward a new function: sensing. They have developed a new ultra-high-frequency, or UHF, RFID tag-sensor configuration that senses spikes in glucose and wirelessly transmits this information. In the future, the team plans to tailor the tag to sense chemicals and gases in the environment, such as carbon monoxide.
“People are looking toward more applications like sensing to get more value out of the existing RFID infrastructure,” says Sai Nithin Reddy Kantareddy, a graduate student in MIT’s Department of Mechanical Engineering. “Imagine creating thousands of these inexpensive RFID tag sensors which you can just slap onto the walls of an infrastructure or the surrounding objects to detect common gases like carbon monoxide or ammonia, without needing an additional battery. You could deploy these cheaply, over a huge network.”
Kantareddy developed the sensor with Rahul Bhattacharya, a research scientist in the group, and Sanjay Sarma, the Fred Fort Flowers and Daniel Fort Flowers Professor of Mechanical Engineering and vice president of open learning at MIT. The researchers presented their design at the IEEE International Conference on RFID, and their results appear online this week.
“RFID is the cheapest, lowest-power RF communication protocol out there,” Sarma says. “When generic RFID chips can be deployed to sense the real world through tricks in the tag, true pervasive sensing can become reality.”
Confounding waves
Currently, RFID tags are available in a number of configurations, including battery-assisted and “passive” varieties. Both types of tags contain a small antenna which communicates with a remote reader by backscattering the RF signal, sending it a simple code or set of data that is stored in the tag’s small integrated chip. Battery-assisted tags include a small battery that powers this chip. Passive RFID tags are designed to harvest energy from the reader itself, which naturally emits just enough radio waves within FCC limits to power the tag’s memory chip and receive a reflected signal.
Recently, researchers have been experimenting with ways to turn passive RFID tags into sensors that can operate over long stretches of time without the need for batteries or replacements. These efforts have typically focused on manipulating a tag’s antenna, engineering it in such a way that its electrical properties change in response to certain stimuli in the environment. As a result, an antenna should reflect radio waves back to a reader at a characteristically different frequency or signal-strength, indicating that a certain stimuli has been detected.
For instance, Sarma’s group previously designed an RFID tag-antenna that changes the way it transmits radio waves in response to moisture content in the soil. The team also fabricated an antenna to sense signs of anemia in blood flowing across an RFID tag.
But Kantareddy says there are drawbacks to such antenna-centric designs, the main one being “multipath interference,” a confounding effect in which radio waves, even from a single source such as an RFID reader or antenna, can reflect off multiple surfaces.
“Depending on the environment, radio waves are reflecting off walls and objects before they reflect off the tag, which interferes and creates noise,” Kantareddy says. “With antenna-based sensors, there’s more chance you’ll get false positives or negatives, meaning a sensor will tell you it sensed something even if it didn’t, because it’s affected by the interference of the radio fields. So it makes antenna-based sensing a little less reliable.”
Chipping away
Sarma’s group took a new approach: Instead of manipulating a tag’s antenna, they tried tailoring its memory chip. They purchased off-the-shelf integrated chips that are designed to switch between two different power modes: an RF energy-based mode, similar to fully passive RFIDs; and a local energy-assisted mode, such as from an external battery or capacitor, similar to semipassive RFID tags.
The team worked each chip into an RFID tag with a standard radio-frequency antenna. In a key step, the researchers built a simple circuit around the memory chip, enabling the chip to switch to a local energy-assisted mode only when it senses a certain stimuli. When in this assisted mode (commercially called battery-assisted passive mode, or BAP), the chip emits a new protocol code, distinct from the normal code it transmits when in a passive mode. A reader can then interpret this new code as a signal that a stimuli of interest has been detected.
Kantareddy says this chip-based design can create more reliable RFID sensors than antenna-based designs because it essentially separates a tag’s sensing and communication capabilities. In antenna-based sensors, both the chip that stores data and the antenna that transmits data are dependent on the radio waves reflected in the environment. With this new design, a chip does not have to depend on confounding radio waves in order to sense something.
“We hope reliability in the data will increase,” Kantareddy says. “There’s a new protocol code along with the increased signal strength whenever you’re sensing, and there’s less chance for you to confuse when a tag is sensing versus not sensing.”
“This approach is interesting because it also solves the problem of information overload that can be associated with large numbers of tags in the environment,” Bhattacharyya says. “Instead of constantly having to parse through streams of information from short-range passive tags, an RFID reader can be placed far enough away so that only events of significance are communicated and need to be processed.”
“Plug-and-play” sensors
As a demonstration, the researchers developed an RFID glucose sensor. They set up commercially available glucose-sensing electrodes, filled with the electrolyte glucose oxidase. When the electrolyte interacts with glucose, the electrode produces an electric charge, acting as a local energy source, or battery.
The researchers attached these electrodes to an RFID tag’s memory chip and circuit. When they added glucose to each electrode, the resulting charge caused the chip to switch from its passive RF power mode, to the local charge-assisted power mode. The more glucose they added, the longer the chip stayed in this secondary power mode.
Kantareddy says that a reader, sensing this new power mode, can interpret this as a signal that glucose is present. The reader can potentially determine the amount of glucose by measuring the time during which the chip stays in the battery-assisted mode: The longer it remains in this mode, the more glucose there must be.
While the team’s sensor was able to detect glucose, its performance was below that of commercially available glucose sensors. The goal, Kantareddy says, was not necessarily to develop an RFID glucose sensor, but to show that the group’s design could be manipulated to sense something more reliably than antenna-based sensors.
“With our design, the data is more trustable,” Kantareddy says.
The design is also more efficient. A tag can run passively on RF energy reflected from a nearby reader until a stimuli of interest comes around. The stimulus itself produces a charge, which powers a tag’s chip to send an alarm code to the reader. The very act of sensing, therefore, produces additional power to power the integrated chip.
“Since you’re getting energy from RF and your electrodes, this increases your communication range,” Kantareddy says. “With this design, your reader can be 10 meters away, rather than 1 or 2. This can decrease the number and cost of readers that, say, a facility requires.”
Going forward, he plans to develop an RFID carbon monoxide sensor by combining his design with different types of electrodes engineered to produce a charge in the presence of the gas.
“With antenna-based designs, you have to design specific antennas for specific applications,” Kantareddy says. “With ours, you can just plug and play with these commercially available electrodes, which makes this whole idea scalable. Then you can deploy hundreds or thousands, in your house or in a facility where you could monitor boilers, gas containers, or pipes.”
This research was supported, in part, by the GS1 organization.
Genesis Nanotechnologyo and l o 
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