Tuning-fork-based fast highly sensitive surface-contact sensor for atomic force microscopy/near-field scanning optical microscopy

Abstract

We have developed a surface-contact sensor on the basis of a tuning fork which differs from the previously described ones in that it has a high operating speed (up to 100 times as fast as the so-called Q limit), requires no external piezoelectric drive, has a sufficiently high sensitivity, and features a “soft” probe attachment which makes the lifetime of the probe equal to that of the standard atomic force microscopy. When using a “soft” probe with a rigidity of 0.5 N/m, one can reliably detect probe tip-to-sample distance variations as small as 0.1 nm. The resonance frequency resolution attained amounted to 2×10−3 Hz. The rate of transient rise is τ=1.5 ms (this refers to the response time of the sensor proper with the Z-coordinate feedback loop open and not to the response time of the microscope as a whole). We have theoretically substantiated the fact that the Q limit, where Q∼10 000 is the Q factor of the tuning fork proper, is not a fundamental restriction on the operating speed of the sensor. This sensor characteristic is governed by another independent quantity, namely, Q1∼100: the quality factor of the tuning fork preamplifier system that can be varied to suit the experimenter. In that case, the fundamental force limitation on the sensitivity of the sensor, associated with its operating speed and the Q factor of the tuning fork, is Fnoise≈10.4 nN/(√Q√Q1).

Integration of a Fabrication Process for an Aluminum Single-Electron Transistor and a Scanning Force Probe for Tuning-Fork-Based Probe Microscopy

“…Traditionally, TF-based probes consider tips to be an add-on to the tuning fork to remedy for the poor lateral resolution of a bare prong [22]. Electrochemically sharpened W, Fe [23] and PtIr [5] wires, tips broken off the cantilever of commercial AFM probes [24], [25], tips including supporting cantilever broken off AFM commercial probes [26], were glued to one prong end, allowing to achieve a lateral resolution orders of magnitude higher than just with a prong or prong corner, and the ability to do not solely on topography, but on other parameters such as scanning gate or magnetic force measurements. The major drawback is that each probe is assembled manually one by one.…”

Near-field scanning optical microscopy using polymethylmethacrylate optical fiber probes

“…Attainment of such large quality factors enables us to use the specialized low noise, precise and fast electronics to measure the resonant frequency f res and Q-factor of a tuning fork to control the SNOM operation. Both the proprietary electronics earlier designed essentially for the sensors made by a tuning fork and an AFM cantilever glued on it [10,13], and a commercially available electronics equipment from Nanonis SA, Switzerland, specially adapted to work with this particular SNOM, were exploited.…”

A Hydrodynamic Model for Measuring Fluid Density and Viscosity by Using Quartz Tuning Forks

“…In addition, the QTFs are low-cost and commercially used as frequency standards in watches, working at 32.768 kHz. The QTF is widely used in gas sensing based on photoacoustic spectroscopy and photothermal spectroscopy [26][27][28], and scanning probe microscopy applications such as atomic force microscopy (AFM) [29][30][31] and near-field scanning optical microscopy (NSOM) [32][33][34]. In order to estimate the density and viscosity of a liquid at the same time, the hydrodynamic model based on the work of Sader, J.E.…”