Concentration of microparticles and bubbles in standing waves

Production of acoustic radiation force using ultrasound: methods and applications

INTRODUCTION

Acoustic radiation force (ARF) is used in many biomedical applications. The transfer of momentum in acoustic waves can be used in a multitude of ways to perturb tissue and manipulate cells.

AREAS COVERED

This review will briefly cover the acoustic theory related to ARF, particularly that related to application in tissues. The use of ARF in measurement of mechanical properties will be treated in detail with emphasis on the spatial and temporal modulation of the ARF. Additional topics covered will be the manipulation of particles with ARF, correction of phase aberration with ARF, modulation of cellular behavior with ARF, and bioeffects related to ARF use.

EXPERT COMMENTARY

The use of ARF can be tailored to specific applications for measurements of mechanical properties or correction of focusing for ultrasound beams. Additionally, noncontact manipulation of particles and cells with ARF enables a wide array of applications for tissue engineering and biosensing.

Using one-dimensional waveguide resonators to measure phase velocities in bubbly liquids

Resonator techniques can be successfully used to extract effective medium properties from dispersive materials. However, in some cases the dispersion can cause modes to repeat. If repeated modes are not taken into account, the useful range of the resonator technique is limited. A resonance tube containing tethered balloons is used to create a dispersive effective medium. Resonator measurements show that modes do repeat. Direct measurement of the mode shapes allows exploitation of all longitudinal radially symmetric modes and expands the frequency range of the technique. A theoretical model is also used to predict when modes repeat. For the presented data set this method increases the measurement range from below 160 Hz to 3000 Hz excluding the stop band where resonances are damped. A means to account for non-ideal resonator boundary conditions often found in highly dispersive systems is discussed.