Soft Materials Laboratory, Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Laboratory of Fluid Mechanics and Instabilities, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Lab Chip. 2020 Dec 15;20(24):4572-4581. doi: 10.1039/d0lc00691b.
Many natural materials display locally varying compositions that impart unique mechanical properties to them which are still unmatched by manmade counterparts. Synthetic materials often possess structures that are well-defined on the molecular level, but poorly defined on the microscale. A fundamental difference that leads to this dissimilarity between natural and synthetic materials is their processing. Many natural materials are assembled from compartmentalized reagents that are released in well-defined and spatially confined regions, resulting in locally varying compositions. By contrast, synthetic materials are typically processed in bulk. Inspired by nature, we introduce a drop-based technique that enables the design of microstructured hydrogel sheets possessing tuneable locally varying compositions. This control in the spatial composition and microstructure is achieved with a microfluidic Hele-Shaw cell that possesses traps with varying trapping strengths to selectively immobilize different types of drops. This modular platform is not limited to the fabrication of hydrogels but can be employed for any material that can be processed into drops and solidified within them. It likely opens up new possibilities for the design of structured, load-bearing hydrogels, as well as for the next generation of soft actuators and sensors.
许多天然材料显示出局部变化的组成，赋予它们独特的机械性能，这是人造材料无法比拟的。合成材料通常具有在分子水平上定义良好但在微观尺度上定义不佳的结构。导致天然材料和合成材料之间存在这种差异的一个根本区别是它们的加工。许多天然材料是由分隔的试剂组装而成的，这些试剂在定义明确且空间受限的区域中释放，从而导致局部组成变化。相比之下，合成材料通常在批量中进行加工。受自然启发，我们引入了一种基于液滴的技术，能够设计具有可调局部变化组成的微结构水凝胶片。通过具有不同捕获强度的陷阱来选择性地固定不同类型的液滴，可以实现这种空间组成和微观结构的控制。这种模块化平台不仅限于水凝胶的制造，还可以用于任何可以加工成液滴并在其中固化的材料。它可能为结构化、承重水凝胶的设计以及下一代软致动器和传感器开辟新的可能性。
