School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, P. R. China.
School of Microelectronics, Northwestern Polytechnical University, Xi'an, P. R. China.
Electrophoresis. 2022 Feb;43(4):601-608. doi: 10.1002/elps.202100245. Epub 2021 Nov 17.
Droplet-based microfluidics is a modular platform in high-throughput single-cell and small sample analyses. However, this droplet microfluidic system was widely fabricated using soft lithography or glass capillaries, which is expensive and technically demanding for various applications, limiting use in resource-poor settings. Besides, the variation in droplet size is also restricted due to the limitations on the operating forces that the paper-based platform is able to withstand. Herein, we develop a fully integrated paper-based droplet microfluidic platform for conducting droplet generation and cell encapsulation in independent aqueous droplets dispersed in a carrier oil by incorporating electric fields. Through imposing an electric field, the droplet size would decrease with increasing the electric field and smaller droplets can be produced at high applied voltage. The droplet diameter can be adjusted by the ratio of inner and outer flow velocities as well as the applied electric field. We also demonstrated the proof of concept encapsulation application of our paper device by encapsulating yeast cells under an electric field. Using a simple wax printing method, carbon electrodes can be integrated on the paper. The integrated paper-based microfluidic platform can be fabricated easily and conducted outside of centralized laboratories. This microfluidic system shows great potential in drug and cell investigations by encapsulating cells in resource-limited environments.
基于液滴的微流控技术是一种高通量单细胞和小样本分析的模块化平台。然而，这种液滴微流控系统通常采用软光刻或玻璃毛细管进行制造，这对于各种应用来说既昂贵又技术要求高，限制了其在资源匮乏环境中的使用。此外，由于受限于纸基平台能够承受的操作力，液滴的大小变化也受到限制。在此，我们开发了一种完全集成的基于纸张的液滴微流控平台，通过引入电场来实现液滴的生成和细胞的封装，使独立的水性液滴分散在载液中。通过施加电场，可以减小液滴的尺寸，随着电场的增加，较小的液滴可以在高施加电压下产生。通过调节内流和外流的流速以及施加的电场，可以调整液滴的直径。我们还通过在电场下封装酵母细胞来证明我们的纸基器件的封装应用的概念验证。通过使用简单的蜡印方法，可以在纸上集成碳电极。集成的基于纸张的微流控平台可以很容易地在中央实验室之外进行制造。该微流控系统在资源有限的环境中通过封装细胞在药物和细胞研究方面显示出巨大的潜力。
