Black Silicon Slices and Dices Bacteria

Zothecula writes "Originally discovered by accident in the 1980s, black silicon is silicon with a surface that has been modified to feature nanoscale spike structures which give the material very low reflectivity. Researchers have now found that these spikes can also destroy a wide range of bacteria, potentially paving the way for a new generation of antibacterial surfaces."

Comments

Durability?

[fuzzyfuzzyfungus]

Does this stuff have any sort of neat catalytic effects or other cleaning mechanisms, or are the structures so tiny that bacterial polysaccharide goop won't neutralize them inside a week?

sounds like tiny little bacteria-stabbing spikes

[ffflala]

"This structure generates a mechanical bacteria killing effect which is unrelated to the chemical composition of the surface," says Professor Crawford, who is Dean of the Faculty of Life and Social Sciences at Swinburne.

Very low level abrasive... I wonder if and how that might serve as a soap.

a concern

[Anonymous Coward]

As it wears down or chips away over time, can the nano particle surface become airborne and become inhaled having similar issues like asbestos?

Re: a concern

[Anonymous Coward]

In short: no.

Essentially the problem with asbestos was the very high aspect ratio and (obviously) bio-incompatibility.

Black Silicon spikes don't have anywhere near this kind of aspect ratio and are comparatively biocompatible.

Source: doing a silicon surface science nanotechnology masters.

They found similar structure on insects' wings

[Taco Cowboy]

From the TFA:

" ... the wings of the cicada Psaltoda claripennis could shred certain types of rod-shaped bacteria ... "
 
" ... the wings of the Diplacodes bipunctata or Wandering Percher dragonfly were even more deadly, killing both rod-shaped and spherical bacteria ... "

I am very curious.

Since the structures on the WINGS of the insects, do they have some yet-to-be-discovered aero-dynamic functionality, apart from their ability to shred bacteria ?

Re:They found similar structure on insects' wings

[eyenot]

If these are particularly small wings, I suppose that all of these nano spikes might provide some kind of static energy lift similar to what was recently discovered in spiders.

Re:They found similar structure on insects' wings

[fuzzyfuzzyfungus]

If nothing else, attempting to answer that question will probably make computational fluid dynamics types cry bitter tears of computational inadequacy...

The silicon structures they were looking at were in the 500nm range, the dragonfly ones ~240nm. That's a huge amount of additional surface area, and on a scale where interaction with gas molecules will probably owe a vexing and deeply unhelpful amount to causes that we normally leave to the chemists, rather than idealized fluid behavior or largely ideal gas kinetic behavior...

Re:They found similar structure on insects' wings

[fuzzyfuzzyfungus]

I wish the best of luck to whoever gets to model the behavior of a mixed (mostly) nonpolar gas interacting with a dense, more or less randomly packed, array of 240nm spikes, composed of some sort of complex biological polymer arrangement, at the boundary of the (already complex enough) interaction between an insect wing and the surrounding fluid...

(If it turns out that the bugs are capable of using cell membrane potentials to selectively induce dielectric polarization of the air passing over selected parts of the wing surface, or something else verging on plain cheating, I say we back away slowly and let them take over.)

Pretty cool.

[Anonymous Coward]

Can this structure of silicon also be used for other things?

Such as battery anode? Massive surface area would be highly useful.

Inside solid caps? Letting us shrink caps even smaller and still keep the same values.

How about solar cells? Something that provides very low light back is absorbing all it can. And massive surface area would be useful.

Durability - big problem with many exotic surfaces

[Animats]

Durability of an exotic surface structure can be a problem. An example is ultra-hydrophobic coatings. (Now available at retail as Rust-Oleum NeverWet.) They really do repel liquids so thoroughly that coated surfaces can't even get muddy. But they seem to wear out quickly. There are YouTube videos showing that stuff working for ten minutes, then failing. But maybe someone will come up with an improved coating that's tougher.

"Paint-on solar cells" also fall into this category.

Re:Durability - big problem with many exotic surfa

[fuzzyfuzzyfungus]

I imagine that that's why those bugs are getting away with them. Nothing like being biological to get aggressive self-repair capabilities thrown in more or less for free... Pending nanites, no such luck on our end.

Marine anti-fouling coatings have similar trouble: they've tried to make less toxic ones, with specially crafted surface geometry that resists mooring by marine organisms; but the minute it starts to wear out, boom, stuff growing. Even the ones that are laced with ghastly organometallic biocides eventually leach enough to lose effectiveness and have to be stripped and re-applied.

(though, speaking of anti-fouling coatings, if microspike-structures are aerodynamic enough for insect wings and brutally biocidal, I suspect that the world's marine shipping industry would fight like dogs to give you their money if you could paint this stuff on...)

Re:Radar

[SuricouRaven]

I see potential for ultra-efficient solar hot water.