Question: How exactly do you make those tiny beds of nails?

Stuart Higgins answered on 5 Mar 2019:

I take a glass plate which is patterned all-over with tiny dots (each dot is about the same diameter as a hair). I then shine light through the plate and project the design onto a disc of silicon.

(Silicon is same material that computer chips are made from, the discs are 10 cm in diameter and about 0.5 mm thick – and very easy to break … 🤔).

The silicon is coated in a photographic material. Where the light hits the photographic material reacts and hardens. I then wash the rest of it away, which leaves the same pattern of dots on the silicon surface.

I then put the silicon into a machine that blasts particles straight down at the surface. This eats away at the silicon where it isn’t protected by the pattern. The dots slowly become cylinders sticking up from the surface.

I then put it in another machine which blasts more particles at the silicon, this time from all angles. The particles eat away at the top of the cylinder more than the bottom, so it slowly turns into a sharp spike.

I’m left with a flat surface, with a load of spikes sticking out.

Thanks for asking!