Researchers at the Laboratory for Organic Electronics at Linköping University in Sweden has managed to grow living roses with electronic circuits threaded through their vascular systems.
The research isn’t quite at that stage yet, but they have been able to change the hue of the rose’s leaves by applying an electrical current to the system. It’s an impressive start, following two years of research and development, and opens new avenues for studying what happens inside plants.
What’s remarkable is that it uses the plant’s own architecture and biology. But getting to that point was not as simple as running wires through the plant. Instead, the idea was to introduce conductive polymers into the plant’s system. These were dissolved in water, and cut rose stems placed in the water to see if the polymer would be wicked up into the plant’s xylem, the channel in a plant’s stem that carries water to the leaves.
They eventually reached success with a polymer called PEDOT-S:H. When the rose stems were placed in a PEDOT-S:H solution, they absorbed the material readily. Living plants also absorbed it, albeit more slowly, through their root systems. The polymer created a thin film inside the xylem, eventually forming a solid wire as long as 10 centimetres, which the team used to create a basic transistor. The xylem could also continue to absorb water and other nutrients normally.
The team also sent another variant of PEDOT together with a nanocellulose into the rose’s leaves. The cellulose forms a tiny, sponge-like 3D 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 in the leave. When an electrical current is applied, this slightly changes the hue of the leaf.