Ever wanted to grow your own TARDIS?
Breeding electronics is not a new idea in science fiction. Not only the Doctor’s most faithful companion is indeed a mix of organic and non-organic material that can be grown out of a piece of itself. Moya, in Farscape, is also a bio-mechanoid, in this case born from another Leviathan. And so are cylon raiders, from Galactica, the Shadows’ and Vorlons’ ships and the White Stars from Babylon 5. In Hyperion (1989), Dan Simmons also describes enormous tree-ships that are grown to move between the stars. And, actually, the trees in Cameron’s Avatar work like an enormous interconnected circuit.
It’s no surprise, then, that people have been trying to grow, at least partially, their own circuits using bio-stuff. For example, Jean-Baptiste Labrune of Alcatel-Lucent Bell Labs came with the idea of Orgatronics, that combine transducers and microcontrollers with organic materials, mostly wood,
Why would these circuits be interesting? First of all, you don’t build them, you grow them. They would be also way easier to recycle. Plus, according to their creators, they could use alternative power sources. Of course, we’ve got the sun, but let’s not forget that plants present potential differences that may provide some feeding to low power consumption electronics. For example, see how Texas MSP 430 microcontroller can be fed (up to a point) with almost any citric.
There have also been projects to feed conventional circuitry with, e.g. the potential difference created by tree root acidification, so, for example, trees could sense heat and trigger alarms in case of wildfires. However, electronics were conventional, even though they used the tree for power. It would be way better if the trees could grow just so, right?
This is, for example, the work of Andrew Adamatzky at the University of the West of England in Bristol. Based on studies about the electrical impedance of cucumbers and olive trees, he has focused on lettuce seedlings to create some sort of organic wire. The problem with organic stuff is that, unlike metals, it is typically not a good conductor for electricity. Adamatzky placed the seedlings across a 10 mm gap in a circuit, passed 1 uA current through it and measured impedance and potential over 10 minutes. Turns out his stuff behave like a 2.76 MOhms resistor, way higher than metals, but still well under the resistance of a body. He plans to use the seedlings to connect biosystems with silicon devices. The main challenge Adamatzky is facing is how to control the growth of the seedlings, which is in no way well structured. However, given that the resistance of materials change with factors like, for example, temperature, these thingies could be used to create fully organic sensors.
Still a long way to go, but moving in the right direction.
Source (partially): MIT Technology Review