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A rose by any other name would鈥� conduct electricity? The worlds of botany and consumer electronics don鈥檛 typically overlap. But a new device has merged electronics with biology, taking a step towards a world in which plants and computers are more intertwined.
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The breakthrough came earlier this year in a lab in southern Sweden. , a professor of organic electronics at Link枚ping University, led a team that built a working electronic circuit from an ordinary garden rose by filling its veins with conductive polymer.
The experiment opens the door for electronics that can plug into plants. Living tissues are known to be conductive 鈥� with living slime moulds already finding their way into gadgets 鈥� and plants are no exception. Propositions dreamed up by scientists include photosynthesis-powered fuel cells and crops that keep tabs on their own physiological properties.
But first, the Link枚ping team had to figure out whether it was even possible to weave electronics into the flesh of a plant 鈥� and they struggled to find a suitable conductive material. It had to be water-soluble, with decent electrical conductivity, and be able to travel through a plant鈥檚 vascular system and form wires. Many materials that the researchers tried turned out to be toxic for the rose, clogging up at the opening of the stem or failing to stick to the inner surface of the plant鈥檚 veins 鈥� the xylem.
Conducting life
Finally, they found one that worked. PEDOT, or poly(3,4-ethylenedioxythiophene), is a classical conducting polymer used in traditional electronics. The researchers soaked a garden rose, with its roots and leaves removed, in a solution of PEDOT. Over the course of a couple of days, the polymer was taken up by the plant鈥檚 network of xylem and then solidified inside it as a gel. When they peeled away the outer bark and tissue at the bottom of the stem, the researchers could see slender dark wires winding through the rose.
, a postdoctoral researcher who did much of the work, went to show Berggren. 鈥淲hen Eleni showed me these beautiful microscope pictures, we understood immediately: we could make circuits out of this,鈥� Berggren says. 鈥淭he performance, the shape of the wires, were just outstanding, unbelievable.鈥�
The team used the xylem wires to make a transistor 鈥� a basic building block of computing and electronics. They tacked gold electrodes and probes along the length of the plant, then connected it to an external resistor and ran a current through it.
In a second experiment, they flushed PEDOT into the rose鈥檚 leaves, forcing the polymer into its pores using a basic pressure chamber. When they ran a current across the leaf, they saw its colours changing faintly in response to the voltage.
The Link枚ping group aren鈥檛 the first to try plugging into plant life. In 2012, a team at Disney Research led by Ivan Poupyrev linked that could measure how electricity moved through the plant. Their project, nicknamed Botanicus Interacticus, allowed the scientists to track and visualise the movements of a human hand along the plant鈥檚 body. At Massachusetts Institute of Technology, chemical engineer has created 鈥淚ron Man鈥� plants with photosynthesis-boosting nanomachines buried deep inside their chloroplasts.
First steps
Although the research on the electronic rose takes several important first steps towards transforming plants into electronics, Strano cautions that this isn鈥檛 a perfect example of a living circuit. The stem and leaves were severed for the experiment: 鈥渂oth systems,鈥� he says, 鈥渁re quite dead.鈥�
But he does see promise in these new bioelectronics. Existing devices are made from petroleum-derived plastics and use rare earth metals. Devices like the one from the Link枚ping lab don鈥檛 have these problems. 鈥淭hat is a step in the right direction for sustainable technology,鈥� Strano says.
Berggren and his colleagues are interested in building botanical circuits that let them sense and record changing hormone levels in plants. They imagine future systems that might be able to nudge a plant鈥檚 physiological properties in the desired direction, serving as an alternative to genetic modification.
They also think that their biological circuitry could be useful for the paper industry, allowing them to exert more control over growing trees. It was the lab鈥檚 interest in trees that led them to experiment on garden roses, with the flower鈥檚 bark and root system making it a useful miniature model.
The electronic rose is 鈥測et another wonderful development in the field of living technologies 鈥� hybrids of wetware and hardware鈥�, says , a professor of unconventional computing at the Bristol Robotics Laboratory in the UK, who has experimented in the past with .
Adamatzky says this work opens the door to a weird new world: 鈥淚n the very distant future 鈥� neither ourselves nor our kids will see this 鈥� we can grow vegetable computers in our gardens.鈥�
Journal reference: Science Advances, DOI:
(Image credits: Top: Magda Turzanska/Science Photo Library; Second image: Eliot Gomez/Link枚ping University)
