Inner-paddled atomic force microscopy cantilever for rapid mechanical mapping

Abstract

Mechanical characterization methods at the nanoscale are of critical importance for many fields including nanomaterials, micro/nano devices and nanomechanics. As a key tool in nanotechnology, atomic force microscopy (AFM) is widely used due to its high-resolution topography imaging capabilities, and is also recognized as a useful platform for nanoscale mechanical characterization. Contact-resonance AFM, which modulates the tip-sample contact with ultrasonic frequencies and then analyzes the cantilever’s resonance responses, is an important AFM method for viscoelastic characterization. However, contact-resonance AFM requires the cantilever’s contact-resonance frequency and quality factor values to quantify the elastic modulus and loss tangent of the sample. This requires time-consuming frequency sweep, which makes a quantitative scanning impractical, therefore only single-point quantitative measurement and qualitative single-frequency scanning are usually applied. To address this issue, here we present an AFM cantilever design with an integrated inner-paddle substructure, which provides an eigenmode whose resonance keeps consistent, but whose resonance amplitude varies with varying contact stiffness. With this probe, it is hoped to quantify the elastic properties of the sample with fast single-frequency amplitude imaging.