As the tip continued its movement across the surface, the antibody was snapped off the antigen and dragged along until it hit another receptive site.

ECONOMIST: Microscopy

So it ought to be possible to test for the presence of a certain antigen on a surface by dragging a suitable antibody over it, and seeing if it gets stuck going fishing, in effect, on a molecular scale.

ECONOMIST: Microscopy

The antibody was then carefully drawn across the surface at a height that allowed it to recognise and bind to any antigens in its path.

ECONOMIST: Microscopy