Kavitace v medicínských aplikacích
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Diplomová práce se zabývá popisem chování kavitační bublinky v blízkosti pružnéstěny, která v experimentech představuje lidskou tkáň. Chování bublinky jeposuzováno pro různé vzdálenosti bublinky od pružné stěny a různé vlastnosti stěny. V první části práce jsou uvedeny medicínské aplikace, v nichž se využívá jevu kavitace. V další části práce je vysvětlen pojem kavitace a známé interakce mezi kavitační bublinkou a buněčnou stěnou a jsou zmíněny i možné způsoby generování kavitačních bublin v medicínských aplikacích. Práce popisuje sestavu experimentu, zvolené principy měření, způsob generování kavitačních bublin a faktory, které mohou ovlivňovat experiment. Lidská tkán byla při experimentech simulována pomocí medicínského gelu. V práci byly použity čtyři různé vzorky gelu s různými mechanickými vlastnostmi s cílem simulovat různé typy tkání. Vzorky byly rozlišeny procentuálním snížením hustoty oproti lidské tkáni, a to o 25 %, 50 %, 75 % a 100 %. Pro zachycení chování bublinky v blízkosti pružné stěny byla použita CCD kamera. Chování bylo zkoumáno pro bublinky generované pomocí tepelné energie přechodového odporu dotýkajících se elektrod. Ze záznamu z CCD kamery byl vyhodnocen popis chování a interakce kavitační bublinky v blízkosti pružné stěny. Výsledky ukazují, že vlastnosti stěny výrazně ovlivňují chování bublinky a mohou dokonce i zabránit interakci bublinky se stěnou.
This Diploma thesis describes the behavior of cavitation bubbles near the flexible wall, which represents human tissue in experiments. Behavior of the bubbles is assessed for different distances between bubbles and flexible wall and various properties of the wall. Medical applications in which is used the phenomenon of cavitation are shown in the first part. The next part explains the concept of cavitation and known interactions between cavitation bubbles and the cell wall. Possible ways of generating cavitation bubbles in medical applications are also mentioned in this part of diploma thesis. The thesis describes the experimental assembly, the selected measurement principles,a way of generating cavitation bubbles and factors that may influence the experiment. In experiments the human tissue were simulated using medical gel. Four different samples of the gel with different mechanical properties were used in this work to simulate different types of tissue. Samples were sorted by the percentage reduction of density in comparison with the density of human tissue, namely 25%, 50%, 75% and 100%. CCD camera was used to capture the behavior of bubbles in front of the flexible wall. The behavior was investigated for the bubbles generated by heat energy of the transient resistance in the electrode contact area. We used records from the CCD camera to describe of the cavitation bubbles behavior near flexible boundary. The results show that the wall properties greatly influence the behavior of the bubbles and may even prevent the interaction of bubbles with the wall.
This Diploma thesis describes the behavior of cavitation bubbles near the flexible wall, which represents human tissue in experiments. Behavior of the bubbles is assessed for different distances between bubbles and flexible wall and various properties of the wall. Medical applications in which is used the phenomenon of cavitation are shown in the first part. The next part explains the concept of cavitation and known interactions between cavitation bubbles and the cell wall. Possible ways of generating cavitation bubbles in medical applications are also mentioned in this part of diploma thesis. The thesis describes the experimental assembly, the selected measurement principles,a way of generating cavitation bubbles and factors that may influence the experiment. In experiments the human tissue were simulated using medical gel. Four different samples of the gel with different mechanical properties were used in this work to simulate different types of tissue. Samples were sorted by the percentage reduction of density in comparison with the density of human tissue, namely 25%, 50%, 75% and 100%. CCD camera was used to capture the behavior of bubbles in front of the flexible wall. The behavior was investigated for the bubbles generated by heat energy of the transient resistance in the electrode contact area. We used records from the CCD camera to describe of the cavitation bubbles behavior near flexible boundary. The results show that the wall properties greatly influence the behavior of the bubbles and may even prevent the interaction of bubbles with the wall.
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Kavitační bublinka, pružná stěna, stand-off parametr, Cavitation bubble, flexible boundary, stand-off parameter