Microfabricated tip arrays for improving force measurements

Variability in the coverage or usable lifetime of active molecules at the apex of an atomic force microscope (AFM) tip is a key limitation to biomolecular force measurements with AFM. Microfabricated tip arrays make it possible to measure molecular forces between large arrays of biological molecules with AFM. The forces are measured between a probeless microfabricated cantilever and a microfabricated array containing approximately 10(5) addressable probes with variable radii. We measure intermolecular forces between the model ligand-receptor pair streptavidin-biotin, to demonstrate that these tip arrays can circumvent these coverage and lifetime obstacles. Further development of these arrays promises to provide a means for measuring millions of different intermolecular interactions, paving the way for AFM to be realistically applied to screen combinatorial libraries. (C) 1999 American Institute of Physics. [S0003-6951(99)05010-X].