Multilayered microfluidic channels integrated with functional microcomponents are the general trend of future biochips, which is similar to the history of Si-integrated circuits from the planer to the three-dimensional (3D) configuration, since they offer miniaturization while increasing the integration degree and diversifying the applications in the reaction, catalysis, and cell cultures. In this paper, an optimized hybrid processing technology is proposed to create true multilayered microchips, by which >“all-in-one” 3D microchips can be fabricated with a successive procedure of 3D glass micromachining by femtosecond-laser-assisted wet etching (FLAE) and the integration of microcomponents into the fabricated microchannels by two-photon polymerization (TPP). To create the multilayered microchannels at different depths in glass substrates (the top layer was embedded at 200 μm below the surface, and the underlying layers were constructed with a 200-μm spacing) with high uniformity and quality, the laser power density (13~16.9 TW/cm2) was optimized to fabricate different layers. To simultaneously complete the etching of each layer, which is also important to ensure the high uniformity, the control layers (nonlaser exposed regions) were prepared at the upper ends of the longitudinal channels. Solvents with different dyes were used to verify that each layer was isolated from the others. The high-quality integration was ensured by quantitatively investigating the experimental conditions in TPP, including the prebaking time (18~40 h), laser power density (2.52~3.36 TW/cm2) and developing time (0.8~4 h), all of which were optimized for each channel formed at different depths. Finally, the eight-layered microfluidic channels integrated with polymer microstructures were successfully fabricated to demonstrate the unique capability of this hybrid technique.
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机译：集成有功能微组件的多层微流体通道是未来生物芯片的普遍趋势，这与从平面到三维（3D）配置的Si集成电路的历史相似，因为它们可实现小型化，同时提高集成度并使其多样化在反应，催化和细胞培养中的应用。本文提出了一种优化的混合处理技术来创建真正的多层微芯片，通过飞秒激光的连续3D玻璃微加工程序可以制造>“ 多合一” 3D微芯片。辅助湿法蚀刻（FLAE），以及通过双光子聚合（TPP）将微组件集成到制造的微通道中。为了在玻璃基板中创建不同深度的多层微通道（顶层埋置在表面下方200μm，底层以200μm的间距构造），具有高的均匀性和高质量，激光功率密度（13〜优化了16.9 TW / cm 2 ）以制造不同的层。为了同时完成对每一层的蚀刻，这对于确保高均匀性也很重要，在纵向通道的上端准备了控制层（非激光暴露区域）。使用具有不同染料的溶剂来验证每一层是否彼此隔离。通过定量研究TPP中的实验条件，包括预烘焙时间（18〜40 h），激光功率密度（2.52〜3.36 TW / cm 2 ）和显影时间（ 0.8〜4 h），所有这些都针对在不同深度形成的每个通道进行了优化。最后，成功地制造了与聚合物微结构集成的八层微流控通道，以展示这种混合技术的独特功能。
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