Monolithically fabricated double-ended tuning-fork-based force sensor

Abstract

A highly sensitive force sensor that is suitable for precise gap control is presented. It combines a double-ended tuning fork (DETF) resonator with a cantilever beam. When the force to be measured is applied to the cantilever beam, the resonant frequency of the DETF beam changes due to the change in axial force. The DETF-based sensor can detect the force as an amplitude change due to the resonant frequency change. The performance of the sensor was theoretically and experimentally investigated. The sensor is rigid and can measure the force with a change in the sample or probe height of less than about 1nm. The experimentally attained minimum detection limit of the force was 19μN and this can be improved by more than one order of magnitude according to theoretical estimation. The combination of the DETF-based sensor and the fixed probe or sample is expected to provide the measurement of the surface force with precise gap control. It can be useful for various fields such as interface science, probe microscopy, and microtribology.

Simultaneously Measuring Lateral and Vertical Forces with Accurate Gap Control for Clarifying Lubrication Phenomena at Nanometer Gap

“…In addition, vibration of the tuning fork may induce vertical vibration with an amplitude of A dv . With consideration of these two displacements, the vertical displacement of the load beam edge or that of the probe Dz p is given by [6], [10] …”

“…For measuring vertical force, a force sensor using a double-ended tuning fork (DETF) resonator was developed (Fig. 1b) [6]. In this DETF force sensor, the resonant frequency of the tuning fork changes through the change of the axial force F d when the force F v is applied to the load beam.…”

Modeling Bearing and Shear Forces in Molecularly Thin Lubricants

“…A double-ended tuning fork (DETF) resonator [19] was recently added to the FWM apparatus to simultaneously measure the vertical force. The dynamic viscosity obtained from FWM measurements was used with classical continuum theory to predict the normal (bearing) force acting on the shearing probe [20].…”

Design and fabrication of a novel resonant surface sensitive to out-of-plane forces for the indentation and injection of living cells

“…Thanks to the high quality factor of the structure, each displacement increment imposed to the central beam caused drastic amplitude changes in the oscillation amplitude of the resonant outer beams. These easily detectable amplitude changes permitted to recover frequency shifts, as detailed in [16].…”