Ye Wen-Qi, Liu Xiao-Peng, Ma Ruo-Fei, Yang Chun-Guang, Xu Zhang-Run
Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, China.
Lab Chip. 2023 Apr 12;23(8):2068-2074. doi: 10.1039/d3lc00027c.
Open microfluidics has attracted increasing attention over the last decade because of its flexibility and simplicity with respect to cell culture and clinical diagnosis. However, traditional valves and pumps are difficult to integrate on open-channel microfluidic chips, in which a liquid is usually driven by capillary forces. Poor fluid control performance is a common drawback of open microfluidics. Herein, we proposed a method for controlling the liquid flow in open channels by controlling the continuous Laplace pressure induced by the deformation of the shape memory microstructures. The uniformly arranged cuboidal microcolumns in the open channels have magnetic/light dual responses, and the bending angle of the microcolumns can be controlled by adjusting Laplace pressure using near-infrared laser irradiation in a magnetic field. Laplace pressure and capillary force drove the liquid flow together, and the controllable fluid transport was realized by adjusting the hydrophilicity of the channel surface and the bending angle of the microcolumns. We demonstrated the controllability of the flow rate and the directional transport of water along a preset path. In addition, the start and stop of water transport were realized local hydrophobic modification. The proposed strategy improves poor fluid control in traditional open systems and makes fluid flow highly controllable. We tried to extract and detect rhodamine B in tiny droplets on the open microfluidic chip, demonstrating the advantages of the proposed strategy in the separation and analysis of tiny samples.
在过去十年中，开放式微流控技术因其在细胞培养和临床诊断方面的灵活性和简易性而受到越来越多的关注。然而，传统的阀门和泵难以集成到开放式微流控芯片上，在这种芯片中，液体通常由毛细作用力驱动。流体控制性能不佳是开放式微流控技术的一个常见缺点。在此，我们提出了一种通过控制形状记忆微结构变形所产生的连续拉普拉斯压力来控制开放式通道中液体流动的方法。开放式通道中均匀排列的长方体微柱具有磁/光双重响应，通过在磁场中使用近红外激光照射来调节拉普拉斯压力，可以控制微柱的弯曲角度。拉普拉斯压力和毛细作用力共同驱动液体流动，通过调节通道表面的亲水性和微柱的弯曲角度实现了可控的流体传输。我们展示了流速的可控性以及水沿预设路径的定向传输。此外，通过局部疏水改性实现了水传输的启动和停止。所提出的策略改善了传统开放式系统中流体控制不佳的问题，使流体流动具有高度可控性。我们尝试在开放式微流控芯片上从小液滴中提取和检测罗丹明B，证明了所提出策略在微小样品分离和分析方面的优势。
