Projects per year
Abstract
Direct measurement of the forces experienced by micro-spheres in an acoustic standing wave device have been obtained using calibrated optical traps generated with holographic optical tweezers. A micro-sphere, which is optically trapped in three dimensions, can be moved through the acoustic device to measure forces acting upon it. When the micro-sphere is subjected to acoustic forces, it's equilibrium position is displaced to a position where the acoustic forces and optical forces are balanced. Once the optical trapping stiffness has been calibrated, observation of this displacement enables a direct measurement of the forces acting upon the micro-sphere. The measured forces are separated into a spatially oscillating component, attributed to the acoustic radiation force, and a constant force, attributed to fluid streaming. As the drive conditions of the acoustic device were varied, oscillating forces (>2.5 pNpp) and streaming forces (<0.2 pN) were measured. A 5 μm silica micro-sphere was used to characterise a 6.8 MHz standing wave, λ = 220 μm, to a spatial resolution limited by the uncertainty in the positioning of the micro-sphere (here to within 2 nm) and with a force resolution on the order of 10 fN. The results have application in the design and testing of acoustic manipulation devices.
Original language | English |
---|---|
Article number | 163504 |
Journal | Applied Physics Letters |
Volume | 104 |
Issue number | 16 |
DOIs | |
Publication status | Published - 21 Apr 2014 |
Fingerprint
Dive into the research topics of 'Measurements of the force fields within an acoustic standing wave using holographic optical tweezers'. Together they form a unique fingerprint.Projects
- 1 Finished
-
ELECTRONIC SONOTWEEZERS: PARTICLE MANIPULATION WITH ULTRASONIC ARRAYS
Drinkwater, B. W. (Principal Investigator)
1/07/09 → 1/07/13
Project: Research