/ 9 November 2018

Bionic mushrooms are a thing now

(Graphic: John McCann/M&G)
(Graphic: John McCann/M&G)

Before Hollywood’s preoccupation with turning old TV shows into awful movies had run its course, there was an attempt by comedian Jim Carrey to reboot Die Man van Staal.

That’s what the show was called in South Africa, anyway. Its undubbed English title was The Six Million Dollar Man — a reference to the cost of turning the mortally wounded Steve Austin into a bionic man by reconstructing his broken body with the latest electronic and mechanical technology. Rebuilding him. Making him better, stronger, faster. The show had it all: action, drama, tracksuits …

The joke behind the remake was that it would still be called The Six Million Dollar Man. But $6-million doesn’t buy you much futuristic tech these days. So instead of being faster, stronger and better he would be weaker, wonkier and prone to falling apart. He would also be Jim Carrey.

Fortunately, that particular remake never made it out of development. It could have ruined bionics for the rest of us, and we might never have been introduced to the world’s first bionic mushroom.

In a paper published this week in the journal Nano Letters, researchers from the Stevens Institute of Technology in New Jersey have detailed their work using 3D-printing techniques to combine aspects of microbiology and nanotechnology to produce a mushroom capable of generating electricity.

The power-generation is interesting in its own right. Regular photovoltaic efficiency has more or less plateaued, with the average solar panel able to convert about 22% of the energy received from sunlight into usable electricity. But research into bioelectricity is still getting started.

Like our bionic man Steve Austin, cyanobacteria first found themselves being tinkered with in the 1970s, when researchers began to figure out how to hijack their biochemical ability to harness the sun’s energy. Unfortunately, the resultant microbial fuel cell (MFC) technology was able to produce only a minuscule amount of electricity.

An MFC is comprised of electrodes that process organic fuel, oxidised by the bacteria, to form a circuit and generate a tiny electrical current.

Even now, 40-odd years later, the most power an MFC can produce is about 25 watts per cubic metre of bacteria, water and nutrition (in a ratio optimised for maximum energy production). That’s not even half of the energy needed to power a regular light bulb — and it requires constant replenishment of food for the bacteria. By comparison, a solar panel at the lower end of 2018’s efficiency spectrum — 18.75% — can generate 350 watts on its own in average sunlight conditions, without constant upkeep.

But MFCs have prompted research into new applications of the photosynthesizing capabilities of the cyanobacteria, using techniques from outside the usual box of microbiological tricks, including nanotech and 3D-printing.

By intertwining cyanobacterial cells with graphene nanoribbons (strands of conductive carbon just a few atoms thick) the team at Stevens have streamlined and miniaturised the bioelectric process.

They 3D-printed a fibonacci-sequence pattern of the graphene over a spiral of the cyanobacteria on the cap of the mushroom, both sparking and capitalising on the symbiosis between fungus and microbe.

The living mushroom provided nutrition and hydration to the cyanobacteria, prompting the production of photosynthetic bioelectricity, enough to feasibly power an array of LEDs.

Having a bionic mushroom at all is well and good, if regrettably phallic. But, as with the MFCs before them, the power produced is nothing to write home about.

What is remarkable is the discovery that 3-D printing the lattice in geometrically variable (anisotropic) densities resulted in a nearly eightfold increase in energy being produced when compared with the usual geometrically uniform (isotropic) castings, using the same amount of material.

The Stevens researchers note that this extraordinary magnification of effect points to the potential of “multi­dimensional integration between different microbiological kingdoms” (in this case, fungal and microbial) that could lead to “next-generation bionic architectures”, which may prompt significant development and breakthroughs not just in the production of bioelectricity, but also in the deeper interaction of technological and ­biological mechanisms or, as it’s sometimes called, bionics.

The bionic mushroom is now a thing. It might not be stronger, faster or better than your average solar panel just yet, but it’s only starting its journey — and the clever money says a grow-your-own-electricity technology of one sort or another will one day supplant the silicon factories that are currently our renewable energy go-to.

In the meantime, we do — as it ­happens — have a Man van Staal reboot to look forward to. The Six Billion Dollar Man is due to hit ­cinemas in 2020. It will star Mark Wahlberg in a tracksuit.