Reducing probe dependent drift in atomic force microscope with symmetrically supported torsion levers

Drift and thermal instability present significant limitations to atomic force microscopy and other cantilever-based sensor measurements. Most drift has been attributed to the asymmetric geometry of the cantilever, which acts as a chemical and thermal bimorphs. For example, cantilevers drift hundreds of nanometers upon immersion in water. The time course of drift is roughly exponential with a time constant of ∼70 min. Symmetrically supported torsion cantilevers significantly reduce this drift. Prototypical torsion levers have long-term drift of 1.0±0.36 Åmin, more than an order of magnitude smaller than commercial cantilevers. These torsion levers also have extraordinarily high thermal stability. In response to a 20 °C change in bath temperature, they move an average of 15±11 nm, whereas traditional levers deflect by >1 μm.