Operation of a wet near-field scanning optical microscope in stable zones by minimizing the resonance change of tuning forks

Abstract

A resonant shift and a decrease of resonance quality of a tuning fork attached to a conventional fiber optic probe in the vicinity of liquid is monitored systematically while varying the protrusion length and immersion depth of the probe. Stable zones where the resonance modification as a function of immersion depth is minimized are observed. A wet near-field scanning optical microscope (wet-NSOM) is operated for a sample within water by using such a stable zone.

A Multimode Transverse Dynamic Force Microscope—Design, Identification, and Control

“…In many SFMs, the vertical probe is attached to a tuning fork, which is vibrated at its harmonic frequency to horizontally excite the probe, e.g. [10]- [13]. The varying interaction with the thin liquid layer above the sample results in a dynamic change in the probe oscillation (i.e.…”

A super-twisting observer for atomic-force reconstruction in a probe microscope

“…This occurs when the attractive atomic forces dominate the inherent stiffness of the cantilever [4,7] . A Vertically Oriented Probe microscope (VOPM) [8,9,10,11,12,13,14,15] circumvents this difficulty because of its nonstandard design. In this arrangement, a shear force between the cantilever tip and a small ordered water layer is exploited for measurement.…”

“…It increases as the proximity to the specimen increases, and causes a decrease in the oscillation amplitude of the cantilever. Most existing shear force microscopy systems [14,15] use for actuation a tuning fork, and have a resonance frequency usually below 50 kHz. In contrast, Bristol's VOPMs exploit the higher resonance frequency of the cantilever which are often well above 100 kHz or even above 1 MHz [8,9,10,11].…”

“…These combined techniques extend to all classes of shear force microscopes [8,9,10,11,12,13,14,15], but they can also help in general probe microscopy analysis, specifically in biomedical sciences and sub-cellular analysis [16].…”

Near-Field Imaging of Cell Membranes in Liquid Enabled by Active Scanning Probe Mechanical Resonance Control

“…probe is operated on the basis of a scanning probe force sensor, where its mechanical resonance deteriorates in frequency stability and quality (Q) factor in a liquid medium, sensitive to viscosity, density, and temperature. 22 Yet, with the near-field signal very sensitive to tip−sample distance, high precision and stability in the force-feedback is required to avoid imaging artifacts.…”