Photoacoustic radiation force on a microbubble

Abstract

We investigate the radiation force on a microbubble due to the photoacoustic wave which is generated by using a pulsed laser. In particular, we focus on the dependence of pulsed laser parameters on the radiation force. In order to do so, we first obtain a new and comprehensive analytical solution to the photoacoustic wave equation based on the Fourier transform for various absorption profiles. Then, we write an expression of the radiation force containing explicit laser parameters, pulse duration, and beamwidth of the laser. Furthermore, we calculate the primary radiation force acting on a microbubble. We show that laser parameters and the position of the microbubble relative to a photoacoustic source have a considerable effect on the primary radiation force. By means of recent developments in laser technologies that render tunability of pulse duration and repetition frequency possible, an adjustable radiation force can be applied to microbubbles. High spatial control of applied force is ensured on account of smaller focal spots achievable by focused optics. In this context, conventional piezoelectric acoustic source applications could be surpassed. In addition, it is possible to increase the radiation force by making source wavelength with the absorption peak of absorber concurrent. The application of photoacoustic radiation force can open a cache of opportunities such as manipulation of microbubbles used as contrast agents and as carrier vehicles for drugs and genes with a desired force along with in vivo applications.

Extended photoacoustic transport model for characterization of red blood cell morphology in microchannel flow

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“…where c κ is the isothermal compressibility [61,62]. This initial pressure rise can be described by a Gaussian function as can be seen in the following section [62]. The temporal profile can be described by…”

“…Here, the Heaviside step function, θ, is introduced to take into consideration the propagation time when the observation point is outside the PA absorber [61,62]. The integrals J 3a and J 3b contribute significantly to the PA signal.…”

Experimental validation of a high-resolution diffuse optical imaging modality: photomagnetic imaging

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Microbubble trapping in inverted optical tweezers

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