When is a rose not a rose? When it's a transistorized electronic circuit, of course. Scientists at Sweden's Linköping University have implanted a rose with conductive polymers and arranged the resulting circuitry into a real transistor system - complete with a digital switch.
Here's how materials scientist Magnus Berggren turned a rose into a piece of electronics. He started with a rather ordinary rose, the sort of cut flower that a research scientist might give to a mom on her birthday. One such rose was sunk into PEDOT, a water-soluble conductive polymer used to make printed electronic circuits. The rose sucked up the polymer through its xylem (vascular tissue) via the capillary effect, as if the polymer were water. Once inside the rose stem, the polymer precipitated out of solution, becoming a sort of wire, capable of carrying a small charge of electricity. The plant retained most of its vascular system so it continued to look and smell like a rose. The researchers attached gold probes to the new wires and fashioned the assemblage with switches, creating an electronic rose. In their write-up, released in Science Advances, they suggest that the result is digitally analogous to a printed circuit board.
At this stage, the experiment is basically a proof-of-concept project. This is pure research, motivated by curiosity. It's not the sort of experimental work that is expected to yield immediate financial returns. For funding, Professor Berggren used independent research money from the Knut and Alice Wallenberg Foundation. A grant of about $2 million was awarded in late 2012 and could be used on any research Berggren wanted to conduct. “It’s an unbelievable luxury with this kind of money, where you are free to choose who you work with, and also to halt research quickly when it’s not working,” Berggren said.
For 25 years, Magnus Berggren has been a professor at Linköping University’s Organic Electronics Lab where he researches electronic circuitry. Until the Wallenberg Foundation grant, there were no donors interested in what might appear to be esoteric research. The money allowed Dr Berggren to hire three post-doctoral research scientists and then begin the tedious work of testing polymers and designing the botanical circuitry.
The electronic flower survives as long as any other cut rose in a vase, but the researchers are not yet claiming practical applications. The Swedish scientists are working with biologists to see if plants with internal circuitry may be useful for monitoring plant growth and studying physiology. Future applications may turn plants into living fuel cells, using sugars produced by photosynthesis to produce - and deliver - electricity. Or perhaps the technology could turn Christmas trees into power plants that flash their own coloured lights - with no extension cords required.