We discuss various aspects of the quartz tuning fork, ranging from its original purpose as a high quality factor resonator for use as a stable frequency reference, to more exotic applications in sensing and scanning probe microscopy. We show experimentally how to tune the quality factor by injecting energy in phase with the current at resonance (quality factor increase) or out of phase (quality factor decrease), hence tuning the sensitivity and the response time of the probe to external disturbances. The principle of shear force scanning probe microscopy is demonstrated on a simple profiler constructed with equipment available in a teaching laboratory.

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Introduction to the quartz tuning fork

A detailed review on the design and realization of spectrophones exploiting custom quartz tuning forks (QTFs) aimed to applications of quartz-enhanced photoacoustic (QEPAS) trace-gas sensors is rep...

https://www.tandfonline.com/doi/pdf/10.1080/23746149.2016.1271285

Quartz─enhanced photoacoustic spectrophones exploiting custom tuning forks: a review

Application of radiation force in noncontact measurement of the elastic parameters.

The function of many nano- and microscale systems is revealed when they are visualized in both space and time Here, we report our first observation, using four-dimensional (4D) electron microscopy, of the nanomechanical motions of cantilevers From the observed oscillations of nanometer displacements as a function of time, for free-standing beams, we are able to measure the frequency of modes of motion and determine Young’s elastic modulus and the force and energy stored during the optomechanical expansions The motion of the cantilever is triggered by molecular charge redistribution as the material, single-crystal organic semiconductor, switches from the equilibrium to the expanded structure For these material structures, the expansion is colossal, typically reaching the micrometer scale, the modulus is 2 GPa, the force is 600 μN, and the energy is 200 pJ These values translate to a large optomechanical efficiency (minimum of 1% and up to 10% or more) and a pressure of nearly 1,500 atm We note that the observables here are real material changes in time, in contrast to those based on changes of optical/contrast intensity or diffraction

Nanomechanical Motions of Cantilevers: Direct Imaging in Real Space and Time with 4D Electron Microscopy

On the interaction of elastic waves with buried land mines :an investigation using the finite-difference time-domain method

Tuning forks can vibrate in many different modes in which the tines move either in the plane or perpendicular to the plane of the fork. Symmetrical modes can be modeled by the motion of two cantilever beams, antisymmetrical modes by the motion of a beam with free ends. A tuning fork vibrating in its fundamental mode is approximately a linear quadrupole sound source whose strength can be increased by use of a baffle or by touching the stem to a soundboard. The motion of the stem includes strong components at both the fundamental frequency and its second harmonic. Slight alterations in a tuning fork can enhance or suppress either of these components. At large amplitudes, the tines vibrate nonsinusoidally, the nth harmonic increasing approximately as the nth power of the fundamental.

David E. Brown

Papers

On the acoustics of tuning forks