For the first time, scientists from Linköping University in Sweden have successfully created analogue and digital electronic circuits inside living plants, particularly by using the vascular system of living roses to fuse and grow the central components of electronic circuits. This essentially means fusing electronics and roses.
The particular electrical components fused into roses include wires, digital logic, and even display-based elements. This was possible due to a special polymer that is capable of functioning as an electronic wire while still transporting organic material such as water and nutrients across the roses through their respective vascular systems.
Plant biology and integrated electronic circuits
The biological structure of plants is akin to manmade electronic circuits. Their functions have several similarities to a certain extent.
“The roots, stems, leaves, and vascular circuitry of higher plants are responsible for conveying the chemical signals that regulate growth and functions,” the researchers wrote. “From a certain perspective, these features are analogous to the contacts, interconnections, devices, and wires of discrete and integrated electronic circuits.”
In addition, plant growth and function are dependent on ionic and hormonal signals that can be influenced by environmental, physical, and chemical stimuli. These signals are transported throughout the body of the through the xylem channel and phloem vascular circuits. Although artificial regulation of plant is achievable using environmental and chemical stimuli or genetic modification, the Swedish researcher believed that embedding electronic functionality would allow electronic stimulation.
But getting electronic components such as wires inside a rose was not as simple as running them through the vascular system. To fuse electronics and roses, the researchers instead explored several conductive and dissolvable polymers that can be absorbed by the plant. They initially tried a dozen of different polymers that did not work. Some poisoned the plant, others clogged the vascular system, or both.
Creating and infusing electronic wires inside roses
The researchers eventually struck gold with a polymer called PEDOT-S:H—a water-soluble derivative of the conductive polymer PEDOT.
They subsequently used cut rose stems and dipped them in water solution made of dissolved PEDOT-S:H for absorption. As the stems sucked up the solution, they also took in the electronic material. The roses naturally integrated the polymers into their own biology.
Take note that the aforementioned is the same process used to colour flowers by dipping their stems in dyed water solution. In addition, the root systems of living plants are also able to absorb the PEDOT-S:H solution through the root system although the process is slower.
The researchers specifically observed that the dissolved PEDOT-S:H assembled itself inside the xylem of the rose—the channel in the stem of a plant that carries waters and nutrients from the roots to the leaves. The polymer formed into conducting wires up to 10 centimetres in length. The researchers further observed that these wires did not obstruct the passage of vital chemicals that keep the roses alive.
Combining the polymer with electrolytes that surround the xylem channel, the roses now have electrochemical transistors that convert ionic signals to electronic outputs.
Infusing another variant of PEDOT polymer together with a nanocellulose using vacuum infiltration into the roses resulted in a semblance of organic pixel display. The cellulose forms a small and sponge-like three-dimensional structure within the leaves, and the pockets in the sponge then fill with the polymer. This creates electrochemical cells fed by electrolytes in the liquid inside a particular leave. When an electrical current is applied, this slightly changes the hue of the particular leaf.
Apart from infusing electronics and roses, the plants continue to live. In other words, the Swedish researchers are growing roses with electronic circuits in their vascular systems and other electrical components.
Implications of infusing electronics and roses
The implications of infusing wires or electronic components inside plant system are innovative. Take agriculture as an example. Through an integrated electronic component, precision recording of plant status will be possible. Regulation of plant physiology will also become more efficient and targeted.
Because the electronic signals can influence the growth of a plant, electronic-based regulation might be a probable alternative to genetic modification.
There is also a possibility for harvesting energy from photosynthesis. It is important to note that the prospect of using plants as power generators is concerning several researchers and industry players. There is an earlier research that has infused bacteria into plant leaves to convert solar energy into liquid fuel. Another technology introduced by a Dutch company makes use of loss energy from photosynthesis to generate cleaner electricity from living plants.
The entire process of infusing electronics and roses or in any other plant systems can also initiate the start of a new field of plant electronics—a marriage among several fields and disciplines including electronic engineering and biotechnology.
Further details of the study are in the article “Electronic plants” published in 2015 in the journal Science Advances. Magnus Berggren is the lead author of the study. The idea of putting electronics into trees first came during the 90s but funding obstacles prevented the researchers from pursuing the research. Photo credit: Linköping University/Adapted