Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, United Kingdom.
J Acoust Soc Am. 2012 Jun;131(6):4337-48. doi: 10.1121/1.4711010.
The possibility of using acoustic Bessel beams to produce an axial pulling force on porous particles is examined in an exact manner. The mathematical model utilizes the appropriate partial-wave expansion method in spherical coordinates, while Biot's model is used to describe the wave motion within the poroelastic medium. Of particular interest here is to examine the feasibility of using Bessel beams for (a) acoustic manipulation of fine porous particles and (b) suppression of particle resonances. To verify the viability of the technique, the radiation force and scattering form-function are calculated for aluminum and silica foams at various porosities. Inspection of the results has shown that acoustic manipulation of low porosity (<0.3) spheres is similar to that of solid elastic spheres, but this behavior significantly changes at higher porosities. Results have also shown a strong correlation between the backscattered form-function and the regions of negative radiation force. It has also been observed that the high-order resonances of the particle can be effectively suppressed by choosing the beam conical angle such that the acoustic contribution from that particular mode vanishes. This investigation may be helpful in the development of acoustic tweezers for manipulation of micro-porous drug delivery carrier and contrast agents.
以精确的方式研究了使用声学贝塞尔光束在多孔颗粒上产生轴向拉力的可能性。该数学模型在球坐标中利用适当的分波展开方法，同时使用 Biot 模型来描述多孔弹性介质中的波动运动。这里特别关注的是检查贝塞尔光束用于（a）精细多孔颗粒的声学操纵和（b）抑制颗粒共振的可行性。为了验证该技术的可行性，针对不同孔隙率的铝和硅泡沫计算了辐射力和散射形式函数。对结果的检查表明，低孔隙率（<0.3）球体的声学操纵类似于固体弹性球体，但在更高的孔隙率下，这种行为会发生显著变化。结果还表明，后向散射形式函数与负辐射力区域之间存在很强的相关性。还观察到，可以通过选择光束的圆锥角来有效地抑制颗粒的高阶共振，使得来自该特定模式的声贡献消失。这项研究可能有助于开发用于操纵微孔药物输送载体和对比剂的声镊。
