Study of the Mechanical Stability of Glass Nanopipettes under Force Loads

The stiffness modulus and stability loss force were experimentally and theoretically studied for conical glass nanopipettes of various shapes with an outer aperture diameter of ∼100 nm and a wall thickness at the tip of ∼30 nm. The experiments were carried out within a scanning electron microscope chamber by measuring the bending of Si microcantilevers with known stiffness under lateral and axial loads applied to the nanopipette. The experimental results are compared with numerical calculations performed using the finite element method (FEM) within a continuum media model. Satisfactory agreement was obtained between the computational and the experimental data. It has been demonstrated that the glass nanopipette, being a scanning ion-conductance microscopy (SICM) nanoprobe, can simultaneously perform functions of a nanoscale probe for atomic force microscopy (AFM). This opens pathways to the creation of a simple combined SICM/AFM probe and expands the analytical capabilities of scanning probe microscopy.