Imaging soft samples in liquid with tuning fork based shear force microscopy

Abstract

We present a study of the dynamic behavior of tuning forks and the application of tuning fork based shear force microscopy on soft samples in liquid. A shift in resonance frequency and a recovery of the tip vibration amplitude have been observed upon immersion into liquid. Conservation of the vibration mode is confirmed by both direct stroboscopic observation and by detection of the tip vibration amplitude of the tuning fork. Thanks to the partial recovery of the Q factor upon complete immersion into liquid, it is possible to obtain high-resolution images on soft samples in liquid. This opens a new domain of applications for tuning fork based near-field scanning optical microscopes.

Tuning Fork Scanning Probe Microscopes - Applications for the Nano-Analysis of the Material Surface and Local Physico-Mechanical Properties

“…The feedback control can be constructed in a fully digital-electronic manner, so that the implementation of the feedback control is greatly simplified. The quartz tuning forks have been successfully demonstrated under various conditions [3,5,[7][8][9].…”

Scanning Ion Conductance Microscopy

“…Thus possible variations in the local ion conductivity can be analyzed along with the surface topography methods face some principal problems when they are used for imaging in liquids, since electrical shortcuts may occur in the electrolyte medium. Solutions include coating the tuning fork with an electrical insulating layer [47], applying a custom piezo-electrical detection [48], or using a diving bell concept, where a water-air interface is forced close to the sample surface [49]. On the other hand, optical detection of shear forces principally works in liquid just as well as in air [50].…”

Shear‐Force‐Controlled Scanning Ion Conductance Microscopy

“…Piezoelectric detection methods face some principal problems when they are used for imaging in liquids, as electrical shortcuts may occur in the electrolyte medium. Solutions to this problem include coating the tuning fork with an electrical insulating layer [45], applying a custom piezoelectrical detection [46], or using a diving bell concept, where the water-air interface is forced close to the sample surface [47]. On the other hand, optical detection of shear forces principally works in liquid just as well as in air [48].…”