本研究探討在內視鏡醫療系統中，二氧化碳雪花產生裝置之設計及其特性，並探討二氧化碳雪花噴霧對生物體組織之冷凍效應。研究工作包括內視鏡系統中二氧化碳雪花形成腔體之設計，不同液體壓力下之二氧化碳雪花流場量測，及生物體組織之溫度量測等。生物體冷凍治療法是以極低溫的方式進行組織的熱侵襲治療(thermal injury)，通常使用二氧化碳雪花或液態氮等溫度極低的物質當工作介質。二氧化碳雪花粒徑由Malvern粒子分析儀量測，流場特性以粒子影像測速儀(PIV)量測，並作流場觀察及診斷。噴霧流場溫度分佈乃使用熱電偶進行量測，而生物體組織溫度則由紅外線熱影像儀量測，以利分析冷凍噴霧對生物體組織的熱傳影響以及分析其影響區域。結果顯示液態二氧化碳在不同的壓力下，其流量介於0.8～2.6 g/s之間，顯示二氧化碳噴流之流量主要與噴注壓力相關。實驗結果亦顯示，當噴注壓力由40bar增加至60bar時，雪花平均飛行速度由4.0 m/s 加速至12.8 m/s；當腔體管長由20mm增長至 40mm時，雪花平均飛行速度也由7.6 m/s加速至12.0 m/s，而腔體之通氣孔徑則對雪花飛行有減速作用，當通氣孔徑由3.0mm擴大至 6.0mm時，雪花平均飛行速度由8.2 m/s減速至5.0 m/s。當形成腔體長度由25mm增加至40mm時，位於出口軸向0.5cm處雪花平均粒徑由446μm增大至621μm，主要原因是當管長增加時，小顆雪花粒子更容易於腔體內相互碰撞並團聚成大顆粒雪花飛出。實驗結果更顯示當噴注壓力超過55bar時，冷凍噴霧較容易打穿組織上表皮而將低溫傳至組織下方，為避免傷害病灶以外組織，可選擇較適宜之噴注壓力於治療時使用。而當腔體管長增加時，由於雪花生成量以及噴灑錐角擴大，因此對於組織之冷凍區域也愈大，以此結果可選擇不同外型之外接腔體於各種病理條件下應用。

This paper investigates the CO2 snow generation device in the endoscopic system for medical application, and to explore the CO2 snow spray freezing effect in the vitro test .The research including the design of formation chamber under different pressure flow measurement, and temperature measurement of the vitro test. Cryotherapy is a thermal injury to the tissue, commonly used CO2 snow or liquid N2. CO2 snow particle size measurement by the Malvern particle size analyzer, flow field characteristic is measured by particle image velocimetry (PIV). Spray flow field temperature distribution measurement is determined using the thermocouple, and the tissue temperature by measuring infrared thermal imaging device to facilitate the analysis of frozen spray on the organism's thermal impact of the tissue and do analysis of impact area. The results showed that liquid CO2 at different pressures, the flow rate is between 0.8 ~ 2.6 g/s, that shows the flow rate of CO2 jet mainly associated with the injection pressure. The results also show that when the injection pressure increased from 40 to 60 bar, the snow average velocity accelerate from 4.0 m/s to 12.8 m/s; when the length of formation chamber from 20 mm up to 40 mm, the mean velocity from 7.6 m/s to accelerate to 12.0 m/s, while the cavity of the formation chamber is a reduction of snow flying effect, when the cavity extend from the 3.0mm to 6.0mm, the mean velocity of the CO2 snow decrease from 8.2 m/s to 5.0 m/s. When the length of formation chamber increases from 25 mm to 40 mm, the mean particle size of CO2 snow increase by the 446μm to 621μm, the main reason is that when the length increases, the small snow particles more likely to collide with each other in the chamber and snow particles flying out into big reunion. According to these results we can choose different formation chamber to use in a variety of pathological conditions.

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