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曹俊杰 (Chun-Chieh Tsao)
曹俊杰 (Chun-Chieh Tsao)
Investigation of Micropump Components:Micro Membrane vibrators and Valveless Chamber Structures
Investigation of Micropump Components:Micro Membrane vibrators and Valveless Chamber Structures
微泵元件研究設計：薄膜致動器及無閥門微泵腔壁結構
微泵元件研究設計：薄膜致動器及無閥門微泵腔壁結構
A micro membrane vibrator consisting of four bimorph cantilever beams and a membrane is designed, fabricated, and tested here. In order to increase Z-axis displacement, four kinds of the bimorph cantilever beams attached to the membrane are designed. Due to the discrepancy of thermal expansion coefficients between different layers, the membrane moves with temperature change. The four-layer structure including SiO2-polysilicon-insulated SiO2-aluminum is fabricated with four masks. Additionally, backside etching is performed to fabricate membrane structures. The numerical finite element program ANSYS 51 is used to simulate the behavior of different designed membrane vibrators. The maximum Z-axis displacement of the 1000μm×1000μm micro membrane vibrator is 93μm at temperature 200℃ in simulation. According to experiment results, the maximum Z-axis displacement is 117μm when input power is 6.98 W. The maximum working frequency is 30∼40 Hz with the amplitude 5∼10μm. Fabrications are improved continuously in order to have better performance. Testing results are presented to compare with the finite element analysis.
A micro membrane vibrator consisting of four bimorph cantilever beams and a membrane is designed, fabricated, and tested here. In order to increase Z-axis displacement, four kinds of the bimorph cantilever beams attached to the membrane are designed. Due to the discrepancy of thermal expansion coefficients between different layers, the membrane moves with temperature change. The four-layer structure including SiO2-polysilicon-insulated SiO2-aluminum is fabricated with four masks. Additionally, backside etching is performed to fabricate membrane structures. The numerical finite element program ANSYS 51 is used to simulate the behavior of different designed membrane vibrators. The maximum Z-axis displacement of the 1000μm×1000μm micro membrane vibrator is 93μm at temperature 200℃ in simulation. According to experiment results, the maximum Z-axis displacement is 117μm when input power is 6.98 W. The maximum working frequency is 30∼40 Hz with the amplitude 5∼10μm. Fabrications are improved continuously in order to have better performance. Testing results are presented to compare with the finite element analysis.
The conventional chamber structure of a micropump consists of two passive check valves connected to an oscillating diaphragm which creates a chamber volume change. Because the movable check valves may cause many problems such as a high pressure drop across the valves, wear, fatigue of the movable parts, and more complicated fabrication processes, thus in the chamber structures of valveless micropump, we design a new version of the micromachined diffuser/nozzle elements which are used to direct flow into and out of pump chambers. By referring to the previous research, we design two new parts including rounded inlet and reentrant outlet. By means of this special design on shapes of the flow channels, a high net volume flow can be predicted to reach in a pumping cycle.
The conventional chamber structure of a micropump consists of two passive check valves connected to an oscillating diaphragm which creates a chamber volume change. Because the movable check valves may cause many problems such as a high pressure drop across the valves, wear, fatigue of the movable parts, and more complicated fabrication processes, thus in the chamber structures of valveless micropump, we design a new version of the micromachined diffuser/nozzle elements which are used to direct flow into and out of pump chambers. By referring to the previous research, we design two new parts including rounded inlet and reentrant outlet. By means of this special design on shapes of the flow channels, a high net volume flow can be predicted to reach in a pumping cycle.
The thicker chamber structures (i.e. 100μm∼300μm) are possible to induce larger volume stroke. Exposure sources of X-ray and UV light are adopted to fabricate the high-aspect-ratio pump chamber structures. In order to fabricate the thicker structures, the different photoresists including PMMA (the X-ray photoresist) and AZ-4620 (the UV photoresist) are utilized. By in-situ polymerization casting process and the multiple spinning method, these photoresists can be coated thickly between 20μm and 300μm. Through UV and X-ray LIGA techniques, the whole micropump chamber structures including the inlet/outlet flow microchannels can be fabricated with only one mask step.
The thicker chamber structures (i.e. 100μm∼300μm) are possible to induce larger volume stroke. Exposure sources of X-ray and UV light are adopted to fabricate the high-aspect-ratio pump chamber structures. In order to fabricate the thicker structures, the different photoresists including PMMA (the X-ray photoresist) and AZ-4620 (the UV photoresist) are utilized. By in-situ polymerization casting process and the multiple spinning method, these photoresists can be coated thickly between 20μm and 300μm. Through UV and X-ray LIGA techniques, the whole micropump chamber structures including the inlet/outlet flow microchannels can be fabricated with only one mask step.
[1] C. C. Tsao and W. Hsu (1997). Micro Membrane Vibrator with Thermally Driven Bimorph Cantilever Beams, Proceedings of SPIE, 3241, 195-205.
[1] C. C. Tsao and W. Hsu (1997). Micro Membrane Vibrator with Thermally Driven Bimorph Cantilever Beams, Proceedings of SPIE, 3241, 195-205.
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