**Biological Applications and Biohydrodynamics**

92 Hydrodynamics – Advanced Topics

Tanveer, S. & Vasconcelos, G.L. (1994). Bubble Breakup in two-dimensional Stokes flow,

**5** 

*Russia* 

**Laser-Induced Hydrodynamics in Water and Biotissues Nearby Optical Fiber Tip** 

V. I. Yusupov1, V. M. Chudnovskii1 and V. N. Bagratashvili2

This paper is aimed at revealing the mechanisms of therapeutic effects stimulated by a medium power (1–10 W) fiber laser induced hydrodynamics in water-saturated bio-tissues. Modern laser medical technologies widely employ delivery of laser light to irradiated tissues via optical fibers. Optical fiber easily penetrates through needle and endoscopic channels, and laser light can be delivered through a fiber for puncture and endoscopic operations. Several laser medical technologies (puncture multichannel laser decompression of disc, laser intervention upon osteochondrosis, surgical treatment of chronic osteomyelitis, endovenous laser ablation, etc.) are based on effective hydrodynamic processes in water-saturated biotissues. These hydrodynamic processes trigger cellular response and regenerative effects through the specific mechanisms of mechano-biology. In this work, we consider different kinds of effects stimulated by a medium power laser-induced hydrodynamics in the vicinity of a fiber tip surface, in particular, generation of vapor-gas bubbles, fiber tip degradation, and generation of intense acoustic waves. Presence of strongly absorbed agents (in a form of Ag nanoparticles, in particular) in laser irradiated water nearby optical fiber tip results in

One of the modern tendencies in a low-invasive medical therapy is a medium power (1–10 W) laser treatment of connective tissues. The examples of such technologies are: laser engineering of cartilages (Bagratashvili et al., 2006); puncture multichannel laser decompression of disc (Sandler et al., 2002; Sandler et al., 2004); laser intervention upon osteochondrosis (Chudnovskii & Yusupov, 2008); laser treatment of chronic osteomyelitis (Privalov et al., 2001); endovenous laser ablation (Van den Bos et al., 2009); fractional

Treatment of osteochondrosis, for example, is based on laser-induced (0.97 µm in wavelength and 2–10 W in power) formation of multiple channels inside an intervertebral disc using silica fiber with a carbon coated fiber tip surface, in order to enhance laser light absorption nearby the fiber tip. Osteochondrosis is caused by such partial destruction of

appearance of pronounced filamentary structures of these agents.

**1. Introduction** 

**2. Therapeutic motivation**

photothermolysis (Rokhsar & Ciocon, 2009).

*1V.I. Il`ichev Pacific Oceanological Institute, Far Eastern* 

*2Institute of Laser and Information Technologies,* 

*Branch of Russian Academy of Sciences* 

*Russian Academy of Sciences* 
