Fluid motion and pressure fields induced by vibrating spheres are frequently used to investigate the function of biological mechanosensory systems and artificial sensors. The calibration of the sphere motion amplitude (displacement, velocity, acceleration), time course and vibration direction often demands expensive equipment. To mitigate this requirement, we have developed a high-quality, low-cost device that we term a ‘Smart Mechanical Dipole’. It provides real-time measurement of sphere acceleration along three axes and can be used to obtain an accurate stimulation trace. We applied digital filtering to equalize the frequency response of the vibrating sphere, which also reduced unwanted amplitude and frequency changes in the hydrodynamic signal. In addition, we show that the angular orientation of the rod to which the sphere was attached, i.e. axial versus transverse, but not the immersion depth of the sphere affected sphere vibration behavior.
The authors declare no competing or financial interests.
The original question, whether the motion in the case of larger spheres is predictable from standard measurement techniques commonly used in our lab, was raised by H.B. The construction, measurements and frequency compensation shown here were performed by H.H. The manuscript was written predominantly by H.H. and J.M. Improvements for analysis and data representation were made by J.M. and H.B.
The research described in this paper was supported by the Bundesministerium für Bildung und Forschung (BMBF, project number 033 RB 0902A).
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.143388.supplemental
- Received May 17, 2016.
- Accepted July 10, 2016.
- © 2016. Published by The Company of Biologists Ltd