Method and apparatus for nanomechanical measurement using an atomic force microscope

摘要

A control-based approach is provided for achieving accurate indentation quantification in broadband and in-liquid nanomechanical property measurements using atomic force microscope (AFM). Accurate indentation measurement is desirable for probe-based material property characterization because the force applied and the indentation generated are the fundamental physical variables that are measured in the characterization process. Large measurement errors, however, occur when the measurement frequency range becomes large (i.e., broadband), or the indentation is measured in liquid on soft materials. Such large measurement errors are generated due to the inability of the conventional method to account for the convolution of the instrument dynamics with the viscoelastic response of the soft sample when the measurement frequency becomes large, and the random-like thermal drift and the distributive hydrodynamic force effects when measuring the indentation in liquid.

主权项

1. A method of microscopy for a test specimen using an atomic force microscope having a probe that includes a cantilever beam, wherein the beam deflects in response to the probe being brought into proximity with the surface of a sample, wherein the method comprises the steps of:
displacing the probe in a first direction; sensing the deflection of the cantilever beam in the first direction; providing signals indicative of the deflection; and controlling the displacement of the probe in response to the signals indicative of the deflection, wherein the step of controlling the displacement comprises the steps of:
tracking an excitation force for a reference specimen;tracking an excitation force for the test specimen;wherein the probe is displaced such that the excitation force for the test specimen is substantially the same as the excitation force for the reference specimen.