RESEARCHERS at the Laboratory of Organic Electronics, Linkoping University, have transformed roses into living electronic circuits.
Magnus Berggren and his team at Linkoping University, Sweden, worked on the garden rose, Rosa floribunda, introducing semiconductors into the channels usually used to transport water and nutrients.
The scientists made cuttings of the plants to demonstrate wires, basic digital logic, and elements of a display.
While the combination of electronics with biological systems has long been a scientific fantasy and theory, attempts to date had to deal with a raft of challenges, including ensuring the biocompatibility and stability of the device, to prevent damage to fragile organic systems.
Once those challenges are solved, the scientists then have to achieve reliable electronic performance. This has now been achieved for the first time in plants.
Organic electronics do not just rely on electrons for signal carrying: they can also use ions. This allows the use of semiconductor technology to bridge the gap between plant systems and electronics.
The researchers say that since the roots, stems, leaves and vascular circuitry of plants are responsible for conveying the chemical signals that regulate growth and functions, these same functions can be mapped to the contacts, interconnections, devices and wires of discrete and integrated electronic circuits.
In the functionalised garden rose, the scientists demonstrated the four key components of organic electronic circuits using the xylem, leaves, veins and plants’ own chemical signals as the template and an integral part of the circuit elements and functions.
The researchers had to deal with the plants’ ability to adjust, regulate and respond to changes in the chemical environment, and synthesised and investigated various forms of conductive polymers, with their varying charge, size, concentration and acidity.
The group discovered that the semiconducting polymer PEDOT-S could be used to create a network of wires inside the stem without killing the plant. Once the plant sucks up the solution containing the monomer, it forms a hydrogel film inside the channels, creating conductive wires up to 10cm long. The wires were used to form organic electrochemical transistors with logic gate functionality in the stem of the plant.
By introducing biocompatible semiconducting polymers, the scientists also built primitive electrochromic displays inside the roses’ leaves, which change colour when voltage is applied.
According to the researchers, the technology could allow the physiological control of plants, regulating their growth and metabolism, or even harvesting electrical energy from photosynthesis taking place in their leaves.
The ability to control and interface with the chemical pathways in plants could pave the way to applications for energy, environmental sustainability, and new ways of interacting with plants, the researchers claim.