Research Organization for Nano & Life Innovation, Waseda University, 513 Wasedatsurumakicho, Shinjuku-ku, Tokyo 162-0041, Japan.
Department of Electronic and Physical Systems, School of Fundamental Science and Engineering, Waseda University, 3-4-1 Okubo, Shin-juku-ku, Tokyo 145-0065, Japan.
Molecules. 2021 Jun 17;26(12):3707. doi: 10.3390/molecules26123707.
In recent years, research on the application of microdroplets in the fields of biotechnology and chemistry has made remarkable progress, but the technology for the stable generation of single-micrometer-scale microdroplets has not yet been established. In this paper, we developed an efficient and stable single-micrometer-scale droplet generation device based on the fragmentation of droplet tails, called "tail thread mode", that appears under moderate flow conditions. This method can efficiently encapsulate microbeads that mimic cells and chemical products in passively generated single-micrometer-scale microdroplets. The device has a simple 2D structure; a T-junction is used for droplet generation; and in the downstream, multi-branch channels are designed for droplet deformation into the tail. Several 1-2 µm droplets were successfully produced by the tail's fragmentation; this continuous splitting was induced by the branch channels. We examined a wide range of experimental conditions and found the optimal flow rate condition can be reduced to one-tenth compared to the conventional tip-streaming method. A mold was fabricated by simple soft lithography, and a polydimethylsiloxane (PDMS) device was fabricated using the mold. Based on the 15 patterns of experimental conditions and the results, the key factors for the generation of microdroplets in this device were examined. In the most efficient condition, 61.1% of the total droplets generated were smaller than 2 μm.
近年来，微流控技术在生物技术和化学领域的应用研究取得了显著进展，但尚未建立稳定生成单微米级微滴的技术。本文基于尾部断裂开发了一种高效稳定的单微米级微滴生成装置，称为“尾丝模式”，该模式出现在适度的流动条件下。该方法可以有效地封装模拟细胞和化学产物的微珠，并将其封装在被动生成的单微米级微滴中。该装置具有简单的 2D 结构；采用 T 型接头进行液滴生成；在下游，设计了多分支通道用于液滴变形为尾部。通过尾部的断裂成功地产生了几个 1-2 µm 的液滴；分支通道诱导了连续的分裂。我们考察了广泛的实验条件，发现与传统的尖端流方法相比，优化后的流速条件可以降低到十分之一。通过简单的软光刻制作了模具，并使用该模具制作了聚二甲基硅氧烷（PDMS）器件。基于 15 种实验条件图案和结果，考察了该装置中微滴生成的关键因素。在最有效的条件下，生成的总液滴中 61.1%小于 2 μm。
