Biros draw the way to a better understanding of Mars

Using an AFM, the surface "landscape" of an object is drawn on a computer screen. www.nanosurf.ch

What does a biro factory in canton Ticino have in common with NASA's next mission to Mars?

The answer is a machine made by Swiss company, Nanosurf, to examine extremely small objects. The device in question is an atomic force microscope (AFM).

One of NASA’s next Mars missions will make use of the AFM to examine the dust and soil on the red planet to assess its harmful effects on human and robotic explorers.

The mean particle size of Martian atmospheric dust is less than two micrometres (thousandths of a millimetre) so the AFM is needed to image the specks.

Building the first AFM, which is space-compatible, posed all sorts of problems, said Nanosurf’s chief executive, Lukas Howald.

“It had to be miniaturised to meet the power, space and weight requirements of an interplanetary mission and it has to cope with fairly harsh conditions.”

On the ball

Back on earth, the AFM is fully employed in a very different environment – it is used for quality control by Precision Writing Balls, a firm near Lugano, which turns out 14 million ballpoint pens every day.

The ball in the ballpoint measures between 0.38 and 1.6mm in diameter, and is made of hard metal or ceramic that is used as the writing tip. The surface roughness of the ball needs to be between two and ten nanometers (millionths of a millimetre).

“This small sphere which transports the ink should have a certain roughness,” said Loris Scandella, applications and marketing manager for Nanosurf.

“If the roughness is less than two nanometres the ink is not transported, and if the roughness is more than ten nanometres, then the tip starts to smear.”

Atomic force microscopes (AFM) probe a surface with a very fine tip. The coordinates recorded in this way make it possible to gain a three-dimensional image of a surface.

Tunnelling microscope

Nanosurf’s AFM is a close relative of the scanning tunnelling microscope developed at the IBM Zurich research laboratory and which won its inventors a Nobel prize in physics.

It’s a good example of a market where Switzerland leads the field, said Basel physicist, Hans Güntherodt.

“We are very strong in atomic force microscopy. We build most of the prototypes sold by companies worldwide and we have a good expertise and we have equipment here that nobody else has in the world.”

by Vincent Landon