本研究探討微噴嘴(微霧化器)在壓電片驅動下，液體產生噴霧或單液滴顆粒之特性。所設計之壓電噴嘴裝置由上下兩片各為20mm×10mm×250μm矽晶片組成。其上下兩面利用MENS加工成為12mm×3mm×20μm之薄膜，上面之薄膜具有兩個進出料口，其直徑為400μm。上薄膜黏貼一片12mm×4mm×0.7mm之壓電片，下薄膜中心有一個直徑為50μm之噴口。另一噴嘴之下蓋板為10mm×10mm×0.2mm蓋玻片，在蓋玻片中心以雷射加工成80μm之噴口。封裝完成之噴嘴有二，其一為噴嘴孔徑50μm，艙體高度460μm，艙體體積16.56nl;另一為噴嘴孔徑80μm，艙體高度230μm，艙體體積8.28nl之微噴嘴(微霧化器)裝置，用以探討不同成分液體介質之霧化特性。本實驗首先以有限元素分析法，分析矽薄膜之自然頻率及應變特性，作為壓電噴嘴驅動之依據，以產生微液滴。液體供應方式分別為液體之高度水頭高，Syringe Pump推進與抽拉等三種形式，使液體進入噴嘴。實驗結果顯示，液體以高度水頭高的方式注入噴嘴艙體中，即使在壓電驅動下，亦未能產生噴霧。以針筒幫浦(以下稱Syringe Pump)將液體由雙進口推入艙體中，流體因壓力作用下，由噴口孔徑為80μm噴出形成液柱，則在壓電驅動頻率為共振頻率4272~5696之正弦波，會產生均勻尺寸之單液滴。若液體由儲水槽以高度水頭銜接噴口進水端，以水受重力推入艙體中，噴口洩水端銜接Syringe Pump，依靠其抽動液體時，則在壓電驅動頻率242KHz之方波，其波形對稱性30%至50%，可由噴口50μm產生產生之液滴直徑為13μm至18μm之單液滴，驅動頻率是在共振頻率以外則產生噴霧。若工作液體分別為甘油重量百分比10wt%、20wt%、30wt%、40wt%之溶液，則在壓電驅動頻率為236KHz時，產生連續噴霧。在工作流體為水的實驗結果顯示，此壓電微噴嘴(微霧化器)以高度水頭與針筒幫浦抽拉液體之供料方式，在高驅動頻率下可以產生較小之單液滴顆粒，故可發展為高速、高解析度之噴印技術。

This paper investigates the characteristics of a piezoelectric micro-nozzle for the production of mono-size droplet and spray. The micro-nozzle was fabricated by MEMS processes. It consists of the upper and lower chips with dimensions of 20mm×10mm×250m. The upper chip is the silicon chip with two holes having diameter of 400m, one for the liquid supply, the other for liquid outlet in order to control the injection through the nozzle. A piezoelectric chip with size 12mm×4mm×0.7mm was attached on the upper silicon chip to drive the liquid injection through the nozzle. The lower chip has two designs. One is the silicon chip with a nozzle orifice of 50m in diameter. Another is the glass chip with a nozzle orifice of 80m in diameter. Different working media were employed to characterize the micro-nozzles. Finite element analysis was used to analyze the characteristics of the silicon chip and to control the liquid supply. Liquids were supplied in three ways. The first one was supplied by the elevation head of the working media. The second one was supplied by the pushing mode of the syringe pump at the inlet port. The third one was supplied with the combination of elevation head and the pulling mode of the syringe pump at the outlet port. Results showed that no spray injection took place with liquid supply by elevation head even driven by PZT. However, with liquid supply by the pushing mode of the syringe pump, a single stream of mono-sized droplets was injected through the micro-nozzle with 80m orifice under the driving frequency ranging from 4272 Hz to 5695Hz of PZT. It turned out that the diameter of the droplets was from 206m to 183m under different driving frequencies. Furthermore, with the liquid supply by elevation head as well as the pulling mode of the syringe pump, mono-size droplets with diameter of 16m were injected in turns of DOD basis as the PZT was driven by the resonant frequency, 242 kHz, of the micro-nozzle. It should be noted that the micro-nozzle produces a spray as the PZT was driven by the frequencies other than the resonant frequency of the micro-nozzle. Tests were also performed with the working media as the mixture of water and glycerol of 10wt%, 20wt%, 30wt% and 40wt%. With the liquid supply by elevation head as well as the pulling mode of the syringe pump, atomization took place as the PZT was driven at the frequency of 236 kHz under a voltage of 150Vpp. The result shows in a single stream of droplets with droplet size of range from 13m to 18m of the working medium of water for 30℃. It is concluded that this micro-nozzle can be used in the application of printing service with high speed and high resolution.

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