Interfacial forces govern adhesion, friction and chemical bonding at the nanoscale, but conventional atomic force microscopes suffer from a snap-to-contact instability that hides much of the force–distance curve. The NDML is developing a MEMS-based interfacial force microscope that removes this instability through force feedback. The silicon device suspends a probe on serpentine flexures with integrated piezoresistive sensors, while electrostatic comb drives apply a counteracting force so that the probe stays at zero displacement. This allows the instrument to measure the full interaction force as the tip approaches and retracts from a surface. The first experiments will measure the strength of single reversible covalent bonds to guide the design of tougher, more sustainable polymers.
The figure above shows the layout of the device.