Controllable membrane system for the separation of soft particles

复杂流体中细胞的分离和分选仍然是生命科学和各种技术领域的主要挑战。具有可切换孔特性的膜适合于这一任务，因为过滤的高并行化潜力，因此具有高吞吐量。德累斯顿工业大学固体力学研究所和半导体与微系统研究所目前的提案遵循了在复合膜中使用渗透控制进行细胞分离的概念。在该体系中，以聚对苯二甲酸乙二醇酯(PET)膜为骨架，用温度敏感型聚N-异丙基丙烯酰胺(PNIPAAm)水凝胶进行表面聚合。通过激光烧蚀，孔被插入到这个有源结构中。当施加温度刺激时，由于水凝胶膨胀，毛孔打开和关闭。因此，我们实现了具有可重复切换的渗透特性的膜。初步研究表明，上述系统是可以实现的。此外，我们还证明了有限元数值模拟可以用来预测材料的开孔行为。因此，我们的模型可以用来优化膜系统的颗粒阻隔和流体性质。在这些研究的基础上，我们的目标是首先研究由单个可切换孔组成的膜系统。微流体流中的刚性模型颗粒将被用来评估孔隙性能和模拟预测。根据设想的模拟研究的结果，膜复合系统的设计必须适应发生的效应。这些可能是颗粒相互作用和膜变形。然后，新的设计将用于多孔膜的实验研究。在成功开发可控多孔膜复合系统的情况下，我们的目标是将我们的研究扩展到弹性粒子。这将为基于我们的方法开发微流控细胞分离系统铺平道路。

Separation and sorting of cells in complex fluids remain major challenges in life sciences and in various technical fields. Membranes with switchable pore properties qualify for this task due to the high parallelization potential of filtration and therefore high throughput. The present proposal of the Institute of Solid Mechanics and the Institute of Semiconductors and Microsystems at Technische Universität Dresden follows the concept of cell separation using permeation control in composite membranes. In the proposed system, a PET membrane is used as a backbone and is surface polymerized with a temperature sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel. Pores are inserted into this active structure by laser ablation. When a temperature stimulus is applied, the pores open and close due to hydrogel swelling. Thereby, we realize membranes with reproducibly switchable permeation properties. Preliminary studies have shown that the above described system can be realized. Additionally, we have demonstrated that numerical simulations with the Finite-Element-Method can be used to predict the pore opening behavior. Our model can therefore be used for optimizing the membrane system with respect to particle blocking and fluidic properties. Based on these studies, we aim to investigate at first a membrane system comprising a single switchable pore. Rigid model particles in microfluidic flow will be used to assess both the pore performance and the modeling predictions. According to the findings of envisaged simulative studies, the design of the membrane composite system has to be adapted to occurring effects. These can be particle-interactions and membrane deformation. The new design will then be used for experimental investigations of a multi-pore membrane. In case of successful development of the controllable multi-pore membrane composite system, we aim for extending our investigations to elastic particles. This would pave the way towards the development of a microfluidic cell separation system based on our approach.