A droplet-generator-on-a-chip actuated by ECF (electro-conjugate fluid) micropumps
A droplet-generator-on-a-chip actuated by ECF (electro-conjugate fluid) micropumps
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由 ECF（电共轭流体）微泵驱动的片上液滴发生器
DOI：
10.1007/s10404-019-2298-7
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发表时间：
2019
影响因子：
2.8
通讯作者：
Kim Joon-wan
中科院分区：
文献类型：
--
作者：
Mao Zebing;Yoshida Kazuhiro;Kim Joon-wan
用于产生液滴的传统电源是庞大的设备，例如注射泵、恒压系统等，导致难以与其他微流体部件集成。为了克服这一局限性，我们提出并研制了一种电源在22 × 21 × 1 mm芯片上的液滴发生器。紧凑型液滴发生器由两个ECF（电共轭流体）微泵，一个T形连接的SU-8通道，一个水室和三个I/O端口。在我们的方法中，两个ECF微泵用于直接泵送连续相流体（油）和间接泵送分散相流体（水）在芯片上。ECF是一种功能性的电介质油，当其相应的电极被施加高直流电压时，可以产生强烈的、活跃的ECF射流。我们的ECF微泵是由三角棱镜和狭缝电极对（TPSEs），并能够在芯片上精确控制流量。在我们的装置中，油滴中的水由T形结几何形状形成。利用MEMS技术，我们成功地制作了微滴发生器。Span 80和双癸二酸酯（DBD，Tokyo Chemical Industry Co.，Ltd）分别用作表面活性剂和ECF的一种。在T型结发生器的特性实验之前，我们研究了DBD和Span 80在不同浓度（0 wt%，1 wt%，3 wt%和5 wt%）下的混合物的粘度、电导率和相对介电常数。我们还研究了混合物对ECF微泵性能和SU-8流体通道润湿性的影响。在此基础上，我们确定了两相流体的流型图，所产生的液滴直径和液滴产生率为我们的液滴发生器。因此，我们的液滴发生器由ECF微泵驱动，可以实现在芯片上的液滴产生。
The traditional power sources for generating droplets are bulky devices such as syringe pumps, constant pressure systems and so on, resulting in difficult integration with other microfluidic components. To overcome this limitation, we propose and develop a droplet generator with its power sources on a chip (22 × 21 × ~ 1 mm). The compact droplet generator consists of two ECF (electro-conjugate fluid) micropumps, a T-junction channel geometry made of SU-8, a water chamber and three I/O ports. In our methodology, the two ECF micropumps are used to pump the continuous phase fluid (oil) directly and the dispersed phase fluid (water) indirectly on a chip. ECF is a kind of functional and dielectric oil, which can generate a strong and active ECF jet when its corresponding electrodes are applied to high DC voltages. Our ECF micropump is composed of triangular prism and silt electrode pairs (TPSEs) and is able to control flow rates precisely on a chip. In our device, the water in oil droplet is formed by the T-junction geometry. Using MEMS technology, we successfully fabricate the droplet-generator-on-a-chip. Span 80 and dibutyl decanedioate (DBD, Tokyo Chemical Industry Co., Ltd) are used as the surfactant and one type of ECF, respectively. Prior to the characteristic experiments of the T-junction generator, we investigate viscosity, electrical conductivity and relative permittivity of the mixtures of DBD and Span 80 at different concentrations (0 wt%, 1 wt%, 3 wt% and 5 wt%). We also research the impact of the mixtures on the performance of ECF micropumps and the wettability of SU-8 fluidic channels. After that, we confirm the flow pattern diagrams of two-phase fluids, the generated droplet diameter and the droplet production rate for our droplet-generator. Therefore, our droplet generator powered by ECF micropumps can realize the droplet generation on a chip.