Small cantilevers for force spectroscopy of single molecules

Abstract

We have used a simple process to fabricate small rectangular cantilevers out of silicon nitride. They have lengths of 9–50 μm, widths of 3–5 μm, and thicknesses of 86 and 102 nm. We have added metallic reflector pads to some of the cantilever ends to maximize reflectivity while minimizing sensitivity to temperature changes. We have characterized small cantilevers through their thermal spectra and show that they can measure smaller forces than larger cantilevers with the same spring constant because they have lower coefficients of viscous damping. Finally, we show that small cantilevers can be used for experiments requiring large measurement bandwidths, and have used them to unfold single titin molecules over an order of magnitude faster than previously reported with conventional cantilevers.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…Only short and thin cantilevers are soft, have a high sensitivity and a high resonance frequency. Accordingly, several researchers aim to make even smaller cantilevers with higher resonance frequency [43][44][45]. The smallest cantilevers are %10 mm long, 0.1-0.3 mm thick and 3-5 mm wide.…”

High-Speed Force Spectroscopy Unfolds Titin at the Velocity of Molecular Dynamics Simulations

“…Based on HS-AFM, we developed HS-FS with short cantilevers (21). This allowed pulling titin molecules at speeds up to ~4000 µm/s, about 2.5 orders of magnitude faster than conventional AFM and reaching current limits for SMD simulations.…”

Atomic-resolution imaging in liquid by frequency modulation atomic force microscopy using small cantilevers with megahertz-order resonance frequencies

“…So far, applications of small cantilevers have mainly been focused on the highspeed imaging in liquid using amplitude modulation AFM (AM-AFM) [24,16,25]. These previous works demonstrated the improved time response of dynamic-mode AFM obtained by the small cantilevers.…”