Investigation of Input Waveforms on the Performance of a Micropump

• Main Authors: Liu, Yin-Ting, 劉胤廷
• Other Authors: Shen, Jyh-Jong
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/en4uwk

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 105 === Most of the polydimethylsiloxane (PDMS) - membrane micro-peristaltic pumps use three plane PDMS membranes as actuating membranes. Through sequential control of these membranes’ deflections, the pumps can push liquid forward. Our micro-peristaltic pump has two opposite slanted PDMS membranes tandem along the fluid channel. It will produce asymmetric deflections under increasing pneumatic pressure. Experimental results show that our peristaltic pump achieves much higher flow rate than that of a micro peristaltic pump with three flat membranes of similar size. When we use our micro peristaltic pump with sine wave air pressure input, we can get 1.9 times higher flow rate than that with square wave air pressure input at the same frequency. In this study, our goal is to investigate what causes flow-rate difference between these two different air pressure input waveforms. We use computerized numerical control (CNC) to produce an acrylic mold, and use it to cast a PDMS replica. Thermal bounding is used to bond the slanted-membrane layer, the fluid channel layer, and the air channel layer to complete the micro peristaltic pump. From the particle-tracking film, we can observe that the distance of a single particle moves in a cycle when using the sine wave input is 1.9 times longer than that of the square wave input. Micro particle image velocimetry (μPIV) is also applied to observe the flow variation during one cycle. When averaging the maximum flow velocities at the observation points to correlate the flow rate, we find that the number of the sine wave input is 1.9 times of the number of the square wave input. From the experimental observation, we can conclude that as air pressure changes abruptly with square wave input, the slanted membrane can not bring its advantage of asymmetric deflection into full play. Furthermore, when the slanted membrane restores as the air pressure releases suddenly, the membrane will produce a vacuum and cause the backflow, thus reducing the flow rate. On the contrary, when using sine wave input, the air pressure increases slowly, the slanted membrane brings it characteristics of asymmetric deflection into full play, thus improving the pumping efficiency. In addition it will not cause backflow when the slanted membrane restores.