Micromanipulation of sonoluminescing bubbles

Abstract

Micromanipulation of sonoluminescing bubbles is achieved by generating a complex sound field consisting of spatially distributed modes of higher harmonics of a basic driving frequency. Bubbles can be manipulated in space and shifted to any desired spot. The interaction with the complex sound field also allows for specification of the violence of a bubble collapse.

A MEMS Sonoluminescent Ultrasonic Sensor

“…This technique can be exploited to stabilize a microbubble at the precise center of a MEMS fabricated cylindrical micro-chamber. This eliminates the need for a large spherical flask and piezoelectric resonators to create a standing wave pressure field as is necessary in macroscale sonoluminescence [2,[7][8][9]. Generated light pulses can be detected by integrating photodetectors at suitable locations in a MEMS fabricated micro chamber of suitable geometry and dimensions.…”

“…The diameter of the spherical flask is determined by the exciting frequencies of the piezoelectric resonators. The bubble is forced into the center of the resonating chamber by the ultrasonic sound field generated by the resonators due to the primary Bjerknes Force expressed as [8]:…”

“…Where, V(t) is the oscillating volume and pe(r,z,t) is the resonant sound field pressure. Since the introduced bubble has a fixed radius, the resonant sound field pressure can be expressed as [8]:…”

“…Where, o\ -2nf is the resonant frequency, kx = 2k / X is the wave number (this is the spatial analogue of frequency) and X is the wavelength. When the primary Bjerknes force FBjerk is large enough to overcome the buoyancy force, Fg, associated with the bubble, the bubble will become trapped inside the resonating chamber [8], The buoyancy force, F , associated with the bubble can be expressed as [8]:…”

“…These transducers are tuned to the lowest resonant frequency of the container. The frequency is approximately 25 kHz and the amplitude of the driving pressure at the center of the container is 1.2 atm for SBSL to occur [2,[7][8][9].…”