Cyborg Roses Wired with Self-Growing Circuits
The method could one day help produce self-monitoring plants.
Scientists have created a kind of cyborg flower: living roses with tiny electronic circuits threaded through their vascular systems.
The miniscule electronic polymers are inserted into the plant, then almost magically self-assemble thanks to the rose's internal structure.
"In a sense, the plant is helping to organize the electronic devices," said study co-author Magnus Berggren, an organic electronics researcher at Linköping University in Sweden.
The strange cyberplants could one day make it possible to tell flowers when to bloom to avoid an impending frost, or when to put out hormones to prevent a drought.
Berggren and his colleagues have actually been trying to make electronic plants for about a decade. The team focused on rose bushes because they have all the elements of a tree - such as bark, leaves, petioles (stalks that connect leaves to the plant's stem) and a distinctive root system - but they are compact, hardy and available at every corner flower shop.
But every electronic ingredient the team tried seemed to have a flaw. Some spurred the plant to release toxic compounds, essentially poisoning the plant. Others clogged the xylem, or the vascular tissue, used to transport water inside a plant.
The team decided to keep trying with other materials. Lead author Eleni Stavrinidou, a postdoctoral researcher in Berggren's lab, cut the stems of roses and then placed the roses in a solution with a variant of the organic polymer poly(3,4-ethylenedioxythiophene) called PEDOT-S:H, which has good electrical conductivity when hydrated.
After the cut flowers had soaked in the solution of PEDOT-S:H for a day or two, the team peeled back the outer layers of the rose bark, revealing tiny "wires" of the organic polymer that had snaked up 2 inches (5 centimeters) into the stem, the researchers reported Nov. 20 in the journal Science Advances.
"There was a moment during the screening when Eleni [the lead author] showed us all these beautiful wires," Berggren told Live Science. "When I saw those, I immediately understood it was possible to make electronic circuits."
A few days later, the team demonstrated that the wires had electrical conductivity. Since then, the researchers have also created self-assembling series of transistors, one of the fundamental elements of a sensor network.
"If we combine the sensors with delivery devices, we could make a neuronal system to record and sense and regulate the physiology of the plant," Berggren said.
So far, the researchers have made electrical networks up to 8 inches (20 cm) long, and have used slightly different techniques to embed electrical circuits in plants with a different structure, such as celery, Berggren said.
The new embedded sensor network could one day be used to prevent flowers from blooming when a frost is on the way. It could also be used to preferentially improve a plant's productivity when weather conditions are right, Berggren said.
Of course, scientists routinely use genetic engineering to alter the water demands, flowering process and hardiness of plants. Plant genetic modification is safe, well-understood and extremely easy to do. So why go to the trouble of embedding electronics for the same purpose?
Changing some traits, such as flowering time, may be too disruptive to an ecosystem if done permanently, especially if those changes could propagate through forests and fields, Berggren. But an electronic switch would be reversible, he said. Ultimately, Berggren sees plants of the future combining both genetic engineering and electrical sensors, he said.
For food crops, scientists would have to show that organic polymers don't make it into the fruits, seeds or edible portions of the plant. And ultimately, the team hopes to use biological chemicals, such as chlorophyll, to create the electronic circuits, bypassing the potential for environmental contamination as a result, Berggren said.
"We can refine materials in plants to become semiconductors and conductors, and put them back in plants to become devices," Berggren said.
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When wired with bioelectric molecules, garden roses can conduct electricity.
Flowers aren’t just a pretty face in the crowd. They have myriad abilities hidden under colorful exteriors. “Most of the flowers we tend to recognize as striking are those that are attracting insects and birds,” said Jacques Dumais, a plant biophysicist and associate professor of organismic and evolutionary biology at Harvard University. Dumais studies how pollen grains work and what he’s learning has implications for packaging technology and medical applications. He’s not alone in looking to flowers for ideas. A motley interdisciplinary group is converging at the intersection of flowers and technology. They’re exploring everything from flower-based biofuel to robotic flowers that can sense your presence. Here are 10 that we found particularly intriguing.
Vision-Improving Nanoflowers An electronic chip based on digital camera technology could restore eyesight to people with ocular diseases. The challenge, however, has been successfully connecting the chips to healthy nerves. University of Oregon physics professor Richard Taylor is developing "nanoflowers" to bridge the gap. His artificial neurons have fractal shapes based on patterns in nature that are advantageous because of their large surface areas. Taylor described the development in a Physics World article and is working on growing the nanoflowers in the lab. "I'm happy with the label 'flower' because they really do have the shape of flowers," he said of the neurons. "Hopefully in the end we can restore vision."
Flower Robots The Taipei International Flora Exposition, a flower show that displays horticultural, technological, and environmental advancements from around the world also featured robotic flowers. Rows of these flowers, dubbed "Florabots," were created by engineers from the Taipei-based computer company ASUS. TechnologyGuide.com editor Jamison Cush saw the robotic flowers during the expo’s run from November 2010 through April 2010. He reported that the 438 Florabots contain motion and sound detection so they respond to visitors. Each one can alight, sway to music, and awaken the other Florabots nearby. You can watch a video here. The expo organizers called the Florabots "a magical demonstration of the aesthetics of science working with art" and invited visitors to use their RFID bracelets to print off unique Florabot mementos before leaving the hall with the display.
Waterproof Materials Lotus flower leaves are superhydrophobic so water droplets just bounce off. Roses can cling to droplets even while upside down, which is called “the rose petal effect.” Scientists have long studied these flower surfaces to design effective non-adhesive surfaces. Duke University assistant professor of mechanical engineering and materials science Chuan-Hua Chen and his team study lotus leaves. “You have this mystery where all these plants have two levels of roughness when they’re superhydrophobic,” said Jonathan Boreyko, a PhD candidate working with Chen. The scientists from Duke wondered why the drops didn’t get stuck and discovered that rough textures on both the microscale and nanoscale level are crucial for de-wetting the leaf. They published their findings last May in the journal Langmuir. “When you have two levels, you can have partial impalement and shake the drops out,” Boreyko said. “The other implication is when you have dew drops form, they can jump off when they merge together.” Sounds like a revolution in waterproof material is coming.
Flower Wind Trees The Dutch architectural firm NL Architects, based in Amsterdam, envisions a day when flower-like windmills dot the urban landscape. Their conceptual design for "Power Flowers" seeks to turn wind turbines into objects of desire. The architects looked at a turbine already on the market called "Eddy," which the firm calls "strong, affordable, and silent." The original Eddy is under six feet tall and about 4.6 feet wide, making it easy to mount just about anywhere. A vertical axis design enables the carbon fiber and fiberglass turbines to produce a modest 945 kilowatt-hours per year from nearly any direction. "With the emergence of smart grids, it perhaps becomes feasible to use smaller units that are less effective, but also less obtrusive," says the firm’s Power Flowers description. "Can we 'domesticate' the turbines?" To find out, the architects overlaid their design onto numerous photographs of suburbia as well as famous locations, including London and Rome.
Flower Fuel A number of crops are being grown for biofuel production, but one of the few flowering ones is the mustard relative camelina. This bright yellow non-food crop has several advantages, says Scott Johnson, president of the biofuel company Sustainable Oils. Camelina's small seeds are extremely oily and have been produced industrially for millennia. Plus it complements food production because it can be grown in rotation with crops as well as on marginal land, Johnson said. "We've proven that it's a scalable crop,” he said. "It's an annual crop that’s been initially adapted to rather tough conditions." Sustainable Oils, with support from the U.S. military, is developing aviation fuel from camelina. "When you talk about flowers, we hope that people who are used to seeing barren ground will see bright yellow fields producing biofuels," he said. His company isn’t alone: The field of biofuel developers striving for viable sources is packed.
Pollen-Like Biomedicine Harvard University plant biophysicist Jacques Dumais is trying to apply engineering principles to plant biology. He’s been taking a closer look at how grains of pollen function. Their cells contain internal hydrostatic pressure systems that allow the pollen to survive mid-air exposure to dry air en route to the female pistil. "When they’re in air, they fold onto themselves and self-seal," Dumais said. When humans with allergies breathe in pollen grains, each one starts expanding and excretes some of their content. The closed spherical capsules got Dumais thinking about the potential to make artificial ones -- but with a positive end result. "Could we design particles you inhale that are medicine?" he wondered. "Once it's inside your body, you could have a very quick transfer to the blood stream." This precise medicine delivery hasn’t been created yet, but Dumais is looking to leverage the pollen grain’s naturally smart surface.
Scented Signals Humans are drawn to floral scents, and so are some animals. But to what extent do flowers control their scents? Candace Galen is a professor of biological sciences at the University of Missouri-Columbia who is currently studying volatile organic compounds and floral fragrances. Floral fragrances are complex, containing 30 or more different compounds, she said. For an animal approaching a flower, the signal is weak at a distance but more concentrated up close. Getting a better grasp on precisely how those signals interact with olfactory sensors could have implications for combating invasive plants. "It might put out signals of its own to mask the native, or act as barriers to signals natives need to be discovered by animal pollinators," Galen said. She added that decoding flower scents could help us understand the impacts of changes to our planet.
Responsive Packaging “Flowers have had to evolve tricks to fertilize,” said Harvard’s Jacques Dumais. They need to make sure that seeds won’t just sit there and fall to the ground. His research on pollen grains has implications for artificial packaging. As soon as the grains leave the male structure, they begin losing water. To stop this dangerous drought, each grain has smart, responsive surfaces with apertures that fold in. Once the grain reaches equilibrium, the floodgates are closed for the rest of the trip. “We’ve established some basic design principles on how to fold a pollen grain,” Dumais added. He said that now he knows how the grains function, he’d love to work with bioengineers to design smart shell packaging that responds automatically to temperature changes. He points out that flower tricks have inspired other effective products -- seed pods sticking to animal fur was the basis for Velcro.
Vibrant Nanostructures Hibiscus flowers and compact discs share a commonality: They both produce the same illusion of bright colors, reflecting light from ordered grooves in their surfaces. Scientists are now discovering that there’s more of this flower trickery going on than meets the human eye. University of Cambridge scientist Beverley Glover is a biologist who studies plant color and pollinators. Several years ago, she and a team of researchers learned that floral iridescence caused by multiple layers or diffraction gratings similar to CD grooves might be more prevalent than anyone thought. They found it in hibiscus and tulip flowers. Although humans might not be able to see this level of iridescence, bees can. Glover recently created an exhibit about color in nature for the Royal Society’s Summer Science Exhibition in London. The exhibit invites visitors to design their own nanostructures to find out which colors can be seen by bees. For now the exercise is just for fun, but knowing what bees see could become an enormous agricultural advantage.
Gold Microflowers When researchers want to detect signals from molecules, they place the sample in a substrate and use technique that has been around since the 1970s called surface enhanced Raman spectroscopy or SERS. The technique has several applications, including drug discovery, forensic testing, detecting biological and chemical threats, and basic chemical testing. But SERS is limited by how much it can enhance the electromagnetic radiation emitted by molecules. Scientists at the Polish Academy of Sciences' Institute of Physical Chemistry recently figured out a way to significantly enhance signals from the substrates. Their super-substrate does this with gold aggregate spheres that are a micrometer in size. Under a microscope, the gold resembles flowers. “When ragged microflowers are deposited on the surface, they form thick, complex 3-D structures with numerous meeting areas between the petals,” Polish Academy of Sciences PhD student Katarzyna Winkler was quoted as saying in an Academy article about the development. The signals were enhanced by 10 million. The chemists say their microflower substrate is simple and cheap to fabricate, and doesn’t require robots or clean rooms.