Microbubble Trapping by Nonlinear Bubble Oscillation Using Pumping Wave

Abstract

Microbubble manipulation by acoustic radiation force may play an important role in future drug delivery systems, because the required bubble manipulations, such as bubble trapping at the desired position and payload release by bubble destruction using a high-intensity ultrasonic wave, are controlled by ultrasonic waves. In this paper, a novel method of microbubble trapping by bubble nonlinear oscillation is proposed. Two ultrasonic waves, which have a harmonic frequency relation, are used in order to generate the force for trapping bubbles. The first wave is a pumping wave, which has a relatively high sound pressure. This wave is used for inducing the nonlinear oscillation of bubbles. The second wave is a control wave, whose frequency is set to be the harmonic frequency of the nonlinear bubble oscillation. The pressure gradient of the control wave in conjunction with the harmonic component of nonlinear oscillation generates the Bjerknes force applied to bubbles. This force forms multiple traps with a narrow separation for bubbles, which flow into the cross area of the two ultrasonic waves.

Ultrasound directed self-assembly of three-dimensional user-specified patterns of particles in a fluid medium

“…Additionally, dimensional scalability is only limited by attenuation of the ultrasound wave, which can be mitigated by selecting a lowviscosity (bulk and shear) fluid medium. 6 Thus, ultrasound DSA enables organizing patterns of particles for a number of engineering applications, including biological cell manipulation, 7 microbubble filtration, 8 and fabrication of engineered materials with exotic properties based on specific patterns of particles embedded in a matrix. [9][10][11] Employing ultrasound DSA to create user-specified patterns of particles requires relating the ultrasound transducer arrangement and operating parameters (amplitude and phase) to the resulting pattern of particles assembled with a specific standing ultrasound wave field.…”

P5B-8 Self-Trapping of Microbubbles to Surface of Target

“…The ultrasonic standing wave method utilizes the traps of micro bubbles produced at nodes or anti-nodes of the ultrasonic standing wave. The nonlinear bubble oscillation method makes bubble traps at the cross area of ultrasonic pumping wave and ultrasonic control wave, whose frequencies have a harmonic relation [2,3].…”

Continuous and unconstrained manipulation of micro-particles using phase-control of bulk acoustic waves

“…Precise control and manipulation of particles dispersed in a host fluid contained in a reservoir is of critical importance for applications in biology, 1 biomedical devices, 2 process control, 3 and directed self-assembly of nano-and micro-particles, 4 amongst others. Manipulation of particles using acoustic waves can be achieved in two regimes.…”

“…The fluid host medium consists of deionized water mixed with sugar to render the particle neutrally buoyant in the fluid and keep it away from the reservoir walls. The density and sound speed are q p ¼ 1062 kg=m 3 (measured), c p ¼ 2400 m=s (Ref. 17) for the PS particle and q f ¼ 1062 kg=m 3 (measured), c f ¼ 1497 m=s (determined with time-of-flight measurement) for the fluid and, thus, the acoustic contrast factor U ¼ 0:609.…”

“…The density and sound speed are q p ¼ 1062 kg=m 3 (measured), c p ¼ 2400 m=s (Ref. 17) for the PS particle and q f ¼ 1062 kg=m 3 (measured), c f ¼ 1497 m=s (determined with time-of-flight measurement) for the fluid and, thus, the acoustic contrast factor U ¼ 0:609. Figure 4 shows the experimental results, with (a) the sequence of transducer phases that result in trajectory (iv) shown in the inset of Fig.…”