Hydrogels are very popular in biomedical areas for their extraordinary biocompatibility. However, most bio-hydrogels are too brittle to perform micro/nanofabrication. An effective method is cast molding; yet during this process, many defects occur as the excessive demolding stress damages the brittle hydrogels. Here, we propose a brand-new damage-free demolding method and a soft ultrafine fiber mold (SUFM) to replace the traditional mold. Both mechanical and finite element analysis (FEA) reveal that SUFMs have obvious advantages especially when the contact area between hydrogel and mold gets larger. By means of a high-resolution 3D printing called electrohydrodynamic (EHD) printing, SUFMs with various topological structures can be achieved with the fiber diameter ranging from 500 nm to 100 μm, at a low cost. Microfluidics and cell patterns are implemented as the demonstration for potential applications. Owing to the tiny scale of microstructures and the hydrophilicity of hydrogels, significant capillary effect occurs which can be utilized to deliver liquid and cells autonomously and to seed cells into those ultrafine channels evenly. The results open up a new avenue for a wider use of hydrogels in biomedical devices, tissue engineering, hydrogel-based microfluidics and wearable electronics; the proposed fabrication method also has the potential to become a universal technique for micro/nanofabrication of brittle materials.

中文翻译：

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使用3D打印的软超细纤维模具对脆性水凝胶进行微/纳米加工，以实现无损脱模。

水凝胶以其非凡的生物相容性在生物医学领域非常受欢迎。但是，大多数生物水凝胶太脆，无法进行微/纳米加工。一种有效的方法是铸造。然而，在此过程中，由于过度的脱模应力会破坏脆性水凝胶，因此会出现许多缺陷。在这里，我们提出了一种全新的无损脱模方法和一种软超细纤维模具（SUFM）来代替传统模具。力学和有限元分析（FEA）均显示SUFM具有明显的优势，特别是当水凝胶与模具之间的接触面积变大时。通过称为电动流体力学（EHD）打印的高分辨率3D打印，可以以低成本在500 nm至100μm的纤维直径范围内实现具有各种拓扑结构的SUFM。微流体和细胞模式被实现为潜在应用的演示。由于微结构的微小规模和水凝胶的亲水性，发生了显着的毛细作用，可用于自动输送液体和细胞，并将细胞均匀地播种到这些超细通道中。结果为在生物医学设备，组织工程，基于水凝胶的微流控技术和可穿戴电子产品中广泛使用水凝胶开辟了一条新途径。所提出的制造方法也有可能成为脆性材料的微/纳米制造的通用技术。发生显着的毛细作用，可用于自动输送液体和细胞，并将细胞均匀地播种到那些超细通道中。结果为在生物医学设备，组织工程，基于水凝胶的微流控技术和可穿戴电子产品中广泛使用水凝胶开辟了一条新途径。所提出的制造方法也有可能成为用于脆性材料的微/纳米制造的通用技术。发生显着的毛细作用，可用于自动输送液体和细胞，并将细胞均匀地播种到那些超细通道中。结果为在生物医学设备，组织工程，基于水凝胶的微流控技术和可穿戴电子产品中广泛使用水凝胶开辟了一条新途径。所提出的制造方法也有可能成为用于脆性材料的微/纳米制造的通用技术。