振動篩板式霧化產生器特性研究

Abstract

近年來產生氣膠微粒的霧化器常被應用在醫療儀器上，現在常見的呼吸器投藥即是霧化器的應用之一。霧化器可有效的將藥物打碎成氣膠微粒狀，小粒徑微粒比例高且藥物殘餘量低，使呼吸病患者能藉由吸入的方式將藥物有效地送入肺部。現在常見用於治療囊腫性纖維化(cystic fibrosis)、氣喘、慢性肺部阻塞(COPD, chronic obstructive pulmonary disease)以及其他呼吸系統相關疾病。 而判斷霧化器效能的重要指標即是輸出的氣膠微粒的粒徑大小，不同粒徑大小對於呼吸治療的肺沉積效果也不同。根據ICRP(International Commission on Radiological Protection)的資料，微粒可進入肺部深層肺泡沉積的粒徑主要為2至10 μm，粒徑小至0.3 μm時穿透率較高較易到肺部深層的粒徑範圍。 本研究使用Vibrating mesh nebulizers作為研究材料，利用氣膠技術學的方法探討各影響霧化器輸出參數所產生的氣膠微粒粒徑與輸出量，本研究使用白光氣膠分徑儀(Welas)來量測氣膠微粒粒徑；實驗結果顯示有三個面向會影響輸出的粒徑與效率，第一為Vibrating mesh本身結構上的孔徑、孔間距與孔總面積，第二為調控nebulizer的振盪的電子參數如頻率、功率以及電壓等，第三面向為霧化器產生時外在的產生方向與傳輸溶液的方式，皆會影響輸出率與微粒的粒徑。 在本研究的條件下，當頻率為300 kHz，使用0.9%的氯化鈉溶液，目前產生的粒徑最小至約2 μm，最大粒徑可至10 μm，輸出量依傳輸速率不同，最大輸出流率可至4 mL/min；粒徑大小不受孔間距所影響，而輸出量與孔徑大小、孔總面積成正比關係。而振動的頻率越高，粒徑有較小的趨勢，但影響程度不明顯；另外給予的電流越大，輸出量也越多，但電流不影響粒徑分布。本研究所使用的振盪片霧化器最大特點為不受使用方向所影響，可在任何方向產生微粒不影響粒徑大小；雖然傳輸溶液的材料不影響粒徑，但仍須尋找更穩定傳輸溶液的方式與材料。

Recently developed vibrating mesh nebulizers have been reported to have increased output efficiency, minimal residual volume, and high percentage of particles in the emitted respirable and fine particle fraction. This work aimed to investigate and identify the major operating parameters of vibrating mesh nebulizers and their effects on the characteristics of aerosol output. The vibrating mesh plates were customarily made to contain 279~4606 tapered holes. The aperture size was uniform on each plate and varied from 3 to 12 μm. The aperture distance also varied from 75 to 450 μm, to examine the potential of droplet coagulation. The aperture plates vibrated at a fixed frequency (100~300 kHz), which caused the ejection of liquid droplets. These nebulizers were mainly evaluated with 0.9% sodium chloride solution. A syringe pump was employed to carry the solution to the vibrating mesh plate. An aerosol size spectrometer (Welas 3000) was employed to measure the aerosol number concentration and size distribution. The droplet size was found to increase with increasing aperture diameter. The distance between apertures and the frequency applied to the mesh plate did not significantly affect the aerosol concentration and size distribution. For each vibrating mesh of different aperture size and aperture number, there is an optimal vibrating frequency to stably deliver maximum amount of aerosol output. This maximum feeding rate increased with increasing aperture number and applied electric current, but the aerosol size distribution remained the same. Vibrating mesh aerosol generators can be orientation independent, if equipped with capillary transport device, such as fibrous absorbent materials.