An Electrohydrodynamically Driven Actuator with Low Shear Stress for Micro Flow Cytometry

• Main Authors: Yeh, Chia-He, 葉家和
• Other Authors: Liu, Cheng-Hsien
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/57350856992768126725

碩士 === 國立清華大學 === 奈米工程與微系統研究所 === 97 === Flow cytometry is a standard and important tool for clinical medicine and research in biology. However, price of this machine is expensive and it also takes a lot of space. Thus, MEMS fabrication is used to lower down the price and be able to make flow cytometry affordable for labs and research institutes. Besides, recent advanced research about stem cell therapy indicates that some specific kind of stem cells are quite sensitive. Although flow cytometry is convenient for all cells in sorting, the high speed sorting also includes higher possible side stimulation or effects on both sensitive normal cells and stem cells. This research topic proposes a novel flow cytometry design. Compared to other designs, we have lower shear stress. Shear stress implies on cell membrane may cause potential extra effects or even damages. Some research also indicates that some stem cells, such as MSC (Mesenchymal Stem Cell), is practically sensitive to shear stress and other mechanical loading. Under some shear stress stimulation, MSC may either change into another cell or change its physiology. Therefore, we also want to avoid this kind of influence while sorting cells. Various flow cytometries have been developed by taking advantages of hydrodynamic focusing as the main working principle to focus the cells in sample flow. Using conventional hydrodynamic focusing effect, a larger velocity ratio (or “flow rate ratio”), such as 1:25 (sample flow : sheath flow) to 1:70 or even higher, is required. In our design, we are able to lower the required velocity ratio down to near 1:1. This significantly removes the influence and potential damage from the shear stress for sorted cells. Besides, we get rid of the conventional used syringe pump and nozzle-shape flow channel. This makes chip work more convenient and also avoids the sudden changes in pressure and fluid velocity, which might potentially either damage or badly affect the sorted cells. Here we propose a novel design and new aspect of thinking in future corresponding research.