Bulletin of the American Physical Society
68th Annual Meeting of the APS Division of Fluid Dynamics
Volume 60, Number 21
Sunday–Tuesday, November 22–24, 2015; Boston, Massachusetts
Session L37: Minisymposium: Cavitation in Soft Tissue |
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Chair: E. Johnsen, University of Michigan Room: Sheraton Back Bay A |
Monday, November 23, 2015 4:05PM - 4:31PM |
L37.00001: Bioeffects due to acoustic droplet vaporization Joseph Bull Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476. [Preview Abstract] |
Monday, November 23, 2015 4:31PM - 4:57PM |
L37.00002: Design and Control of Functional Microbubbles for Medical Applications of Ultrasound Shu Takagi, Taichi Osaki, Takuya Ariyoshi, Takashi Azuma, Mitsuhisa Ichiyanagi, Ikuya Kinefuchi Microbubbles are used as a contrast agent for ultrasound diagnosis. It is also expected to be use for the treatment. One of the possible applications is microbubble DDS. For that purpose, microbubbles need to be well-controlled for the generating process and manipulation. In this talk, for the design and control of the functional microbubbles, an experimental study on generation and surface modification of microbubbles are explained. Using a T-junction type microchannel, small bubbles about 5$\mu $m size are successfully generated. For the surface modification, Biotin-coated microbubbles are tried to adhere the Avidin-coated wall. Furthermore, the manipulation of the microbubbles using ultrasound is also discussed. Plane-wave and focused ultrasound is used to manipulate a microbubble and bubble clusters. The experimental results are shown in the presentation. [Preview Abstract] |
Monday, November 23, 2015 4:57PM - 5:23PM |
L37.00003: Stretching cells and delivering drugs with bubbles Claus-Dieter Ohl, Fenfang Li, Chan Chon U, Yu Gao, Chenjie Xu In this talk we'll review our work on impulsive cell stretching using cavitation bubbles and magnetic microbubbles for drug delivery. For sufficient short times cells can sustain a much larger areal strain than the yield strain obtained from quasi-static stretching. Experiments with red blood cells show that even then the rupture of the cell is slow process; it is caused by diffusive swelling rather than mechanical violation of the plasma membrane. In the second part we'll discuss bubbles coated with magnetic and drug loaded particles. These bubbles offer an interesting vector for on demand delivery of drugs using mild ultrasound and magnetic fields. We report on basic experiments in microfluidic channels revealing the release of the agent during bubble oscillations and first {\em in vivo} validation with a mouse tumor model. [Preview Abstract] |
Monday, November 23, 2015 5:23PM - 5:49PM |
L37.00004: Bubble-cell interactions with laser-activated polymeric microcapsules Michel Versluis, Guillaume Lajoinie, Tom van Rooij, Ilya Skachkov, Klazina Kooiman, Nico de Jong Polymeric microcapsules that are made light-absorbing by the addition of a dye in their shell can generate cavitation microbubbles with spatiotemporal control when irradiated by a pulsed laser. These particles less than 3 $\mu $m in size can circulate through the body, bind to tissues and are expected to be readily detected, even if a single cavitation bubble is produced. In this paper, we study the impact of such cavitation bubbles on a cell monolayer and quantify it in terms of cell poration and cell viability. Two capsules formulations were used; the first one encapsulates a low boiling point oil and induced less cell damage than the second that was loaded with a high boiling point oil. We also report the generation of stable bubbles by the first capsule formulation that completely absorb the cells in their close vicinity. [Preview Abstract] |
Monday, November 23, 2015 5:49PM - 6:15PM |
L37.00005: Microcavitation as a Neuronal Damage Mechanism in Blast Traumatic Brain Injury Christian Franck, Jonathan Estrada Blast traumatic brain injury (bTBI) is a leading cause of injury in the armed forces. Diffuse axonal injury, the hallmark feature of blunt TBI, has been investigated in direct mechanical loading conditions. However, recent evidence suggests inertial cavitation as a possible bTBI mechanism, particularly in the case of exposure to blasts. Cavitation damage to free surfaces has been well-studied, but bubble interactions within confined 3D environments, in particular their stress and strain signatures are not well understood. The structural damage due to cavitation in living tissues – particularly at the cellular level – are incompletely understood, in part due to the rapid bubble formation and deformation strain rates of up to $\sim$ 105-106 s$^{-1}$. This project aims to characterize material damage in 2D and 3D cell culture environments by utilizing a novel high-speed red-blue diffraction assisted image correlation method at speeds of up to 10$^6$ frames per second. [Preview Abstract] |
Monday, November 23, 2015 6:15PM - 6:41PM |
L37.00006: Bubble dynamics in high-amplitude ultrasound therapies Eric Johnsen, Lauren Mancia Cavitation plays an important role in certain therapeutic ultrasound procedures, such as histotripsy in which megahertz pressure pulses are used to destroy tissue. The large tensions (> 25 MPa) nucleate bubbles in the tissue, which rapidly grow to radii on the order of hundreds of microns and subsequently collapse. To better understand potential cavitation-induced damage, we developed a numerical framework for spherical bubble dynamics in soft tissue that includes liquid compressibility and full thermal effects, as well as a comprehensive viscoelastic model with elasticity, relaxation, viscosity and various nonlinearities. This framework has enabled us to understand the effects of the viscoelastic and thermal properties of the tissue on the bubble dynamics, and compute stress and temperature fields in the surroundings. Results indicate that different viscoelastic properties affect the bubble dynamics differently, but that overall the viscoelastic nature of tissue produces larger stresses and increased heating on the surroundings, compared to bubble dynamics in purely viscous liquids. [Preview Abstract] |
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