Flower Power today could mean harnessing energy from roses – wiring plants up and using them like solar cells to produce electricity through photosynthesis – and not just a love-and-peace Hippy-type dream of the 1960s, says a team of scientists from Linköping University Laboratory for Organic Electronics and the Umeå Plant Science Center, both in Sweden.
Study leader, Professor Magnus Berggren and colleagues wrote in the academic journal Science Advances that it is possible to create both analog and digital electronic circuits within living flowers, trees and bushes.
With the help of channels that distribute nutrients and water in plants, the researchers have built the key components of electronic circuits.
“With integrated and distributed electronics in plants, one can envisage a range of applications including precision recording and regulation of physiology, energy harvesting from photosynthesis, and alternatives to genetic modification for plant optimization,” the authors wrote. (Image: Linköping University)
Roses produce analog and digital electronic circuits
They demonstrated how roses can produce both digital and analog electronic circuits, which could eventually be used to, for example, regulate the physiology of plants.
While traditional electronics send and process electronic signals, plants transport and handle growth hormones and ions. In organic electronics, based on semi-conductive polymers (substances whose molecular structures are built up mainly or entirely from a large number of similar units bonded together), both electrons and ions can serve as signal carriers.
It therefore becomes possible – with the help of organic electronics – to combine the electric signals with that of the plants’, i.e. translating the signals within plants into traditional electronics.
Storing energy from photosynthesis in fuel cells
With cheap organic electronics integrated into plants, several potential applications open up, such as using energy that comes from photosynthesis in a fuel cell, or reading and regulating how plants grow and function.
The scientific team at the Laboratory of Organic Electronics, from the left Daniel Simon, Roger Gabrielsson, Eleni Stavrinidou, Eliot Gomez and Magnus Berggren. Xavier Crispin is missing. (Image: Linköping University)
Co-author, Ove Nilsson, professor of plant reproduction biology at the Umeå Plant Science Center, said:
“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.”
For the past 25 years, Prof. Berggren has been researching printed electronics on paper. He was often drawn by the idea of putting electronics into the tree itself, but failed to get much interest from financial backers.
Prof. Berggren’s dream started to become reality in 2012
Things changed at the end of 2012 when the Knut and Alice Wallenberg Foundation supported his idea with hard cash. He was then able to hire three scientists with new doctorates: Eliot Gomez, Eleni Stavrinidou and Roger Gabrielsson.
Imagine a world where electricity from plants is used as fuel for our cars, home heating, public transport and industry. (Image: Linköping University)
Their task was to determine – with help from more senior scientists at the Umeå Plant Science Center and Linköping University – whether it was possible to introduce and perhaps even produce electronics in plants.
They found it was possible. Within two years, they succeeded in getting plants to produce analog as well as digital circuits.
Mr. Gabrielsson discovered PEDOT-S, a polymer that is soluble in water. When a rose absorbed it, it was converted into a hydrogel which formed a thin film along the channel through which the plant absorbs water and nutrients.
Ms. Stavrinidou then managed to get the plants to produce 10-centimetre segments, 50 cm thick, of membranes (film) of the conductive polymer. They created a transistor by placing an electrode at each end and a gate in the middle.
A fully-functional transistor in a plant
Ms. Stavrinidou said:
“We’ve produced the perfect measurement values, which show that it really is a fully functional transistor.”
Ms. Stavrinidou has measured the polymer’s conductive ability from 0.13 siemens/cm to 1 siemens/cm.
Mr. Gomez used vacuum infiltration – a common method in plant biology – to send another PEDOT variant combined with nanocellulose fibres into the rose’s foliage. The cellulose forms a 3-D structure containing small cavities – similar to a sponge – within the rose leaf, while the cavities are filled with the conductive polymer.
Electrochemical cells are thus formed with several pixels, partitioned by the veins. The fluid in the leaf contains the electrolytes.
Mr. Gomez said:
“We can create electrochromatic plants in which the leaves change color – it’s cool, but maybe not so useful.”
But what is seen as a weakness of organic electronics – the cold and the wet – the plant solves when it encapsulates the polymer and protects it from the elements.
Mr. Gabrielsson commented:
“It seems as if the polymers we use had been created for their function.”
Flower Power- a new field of research
Professor Berggren said:
“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.”
“As far as we know, there are no previously published research results regarding electronics produced in plants. No one’s done this before.”
Citation: “Electronic plants,” Eleni Stavrinidou, Roger Gabrielsson, Eliot Gomez, Xavier Crispin, Ove Nilsson, Daniel T. Simon and Magnus Berggren. Science Advances. 20 November, 2015. DOI: 10.1126/sciadv.1501136.