Effect of ultrasonic attenuation on the feasibility of acoustic tweezers.
A modified mathematical formulation for the calculation of axial radiation force was developed to incorporate the effect of ultrasonic attenuation. Axial forces, Fresnel coefficients, average internal attenuation factors and effective internal reflection coefficients were calculated. Thermal and mechanical indices were also computed to address the safety issues in the implementation of acoustic tweezers and were found to be negligible. The results show that the overall distribution of axial forces is barely affected by attenuation. Furthermore, it is found that attenuation actually works against the scattering force and may therefore reinforce the axial trapping force. For a particle size of 180 microm, the maximum trapping force increases from 29.8 x 10(-11) N to 30.3 x 10(-11) N by 1.7% when attenuation is included. In light of these results, it appears that acoustic tweezers may still be feasible beyond the focal point even under the influence of attenuation.
Lee
Jungwoo
J
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA. jungwool@usc.edu
Shung
K Kirk
KK
D000818:Animals; D001696:Biomechanical Phenomena; D005223:Fats; D006358:Hot Temperature; D008433:Mathematics; D008954:Models, Biological; D010316:Particle Size; D013552:Swine; D014159:Transducers; D014465:Ultrasonics
D005223:Fats