Researchers have figured out how to grow the key components of electronic circuits inside a living plant. Should the breakthrough prove scalable, it could be a major stepping stone in the world of organic technology.
The team from Linköping University (Sweden), under the guidance of Professor Magnus Berggren, successfully used the vascular system of living roses to build key components for wire-, digital logic-, and display-based technologies. They started out by taking a closer look at the plant’s transportation system for ionic signals and hormones. The problem, they found, was that plants operate very slowly; this makes interacting with and studying the actual plants pretty difficult.
So next, the team looked into augmenting the plants with electronic functionality to see if would be possible to combine electric signals with the plant’s chemical processes. This would allow them to control and interface with its chemical pathways which, in turn, could eventually be used for things like photosynthesis-based fuel cells, sensors and growth regulators, and devices that modulate the internal workings of the actual plants.
“Previously, we had no good tools for measuring the concentration of various molecules in living plants. Now we'll be able to influence the concentration of the various substances in the plant that regulate growth and development. Here, I see great possibilities for learning more,” says Ove Nilsson, professor of plant reproduction biology and director of the Umeå Plant Science Center; professor Nilsson also served as co-author of the article.
The actual idea to do this is nothing new — researchers have been trying to put electronics into trees for the paper industry since the 1990s. A lack of success coupled with limited funding put a halt to a lot of these projects.
Independent researcher money from the Knut and Alice Wallenburg Foundation gave the Linköping team a new chance at pursuing the organic technology. Early attempts centered around the idea of introducing conductive polymers through rose stems. There was limited success going this route — just one polymer, called PEDOT-S, synthesized and successfully assembled itself inside the xylem channels as conducting wires while still allowing for water and nutrients to be transported. The team next used this material to create 10cm-long wires in the xylem channels of the rose. By then combining the wires with the electrolyte that surrounds these channels, they were able to essentially create an electrochemical transistor — one that converts the plant’s ionic signals to electronic output.
Another method explored was one that used methods common in plant biology — vacuum infiltration, specifically. This was used to infuse another PEDOT variant into the leaves, whereupon it formed “pixels” of electrochemical cells apportioned by the veins. When voltage was applied to the plant, it caused the polymer to interact with the ions in the leaf which, in turn, changed the color of the PEDOT in a display-like device.
The results to date are nothing more than the early establishment of foundational steps meant for merging all of the many different fields of organic electronics and plant science. The hope in doing this is to one day develop applications for energy, environmental sustainability, and new ways of interacting with plants.
“As far as we know, there are no previously published research results regarding electronics produced in plants. No one's done this before,” Professor Berggren says.”Now we can really start talking about 'power plants' – we can place sensors in plants and use the energy formed in the chlorophyll, produce green antennas, or produce new materials. Everything occurs naturally, and we use the plants' own very advanced, unique systems.”
To learn more, read the team’s paper, aptly entitled Electronic Plants, which was published in the journal Science Advances.
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