Recently, the use of 3D printing technologies has become prevalent in microfluidic applications. Although these technologies enable low-cost, rapid, and easy fabrication of microfluidic devices, fabricated devices suffer from optical opaqueness that inhibits their use for microscopic imaging. This study investigates bonding strategies using polydimethylsiloxane (PDMS) and printer resin as interlayer materials to fabricate high-strength optically transparent 3D-printed microfluidic devices. First, we fabricated microfluidic structures using a stereolithography 3D printer. We placed 3D-printed structures on interlayer materials coated surfaces. Then, we either let these 3D-printed structures rest on the coated slides or transferred them to new glass slides. We achieved bonding between 3D-printed structures and glass substrates with UV exposure for resin and with elevated temperature for PDMS interlayer materials. Bonding strength was investigated for different interlayer material thicknesses. We also analyzed the bright-field and fluorescence imaging capability of microfluidic devices fabricated using different bonding strategies. We achieve up to twofold (9.1 bar) improved bonding strength and comparable fluorescence sensitivity with respect to microfluidic devices fabricated using the traditional plasma activated PDMS-glass bonding method. Although stereolithography 3D printer allows fabrication of enclosed channels having dimensions down to ∼600 μm, monolithic transparent microfluidic channels with 280 × 110 μm2 cross section can be realized using adhesive interlayers. Furthermore, 3D-printed microfluidic chips can be integrated successfully with Protein-G modified substrates using resin interlayers for detection of fluorescent-labeled immunoglobulin down to ∼30 ng/ml. Hence, this strategy can be applied to fabricate high-strength and transparent microfluidic chips for various optical imaging applications including biosensing.

中文翻译：

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胶粘结合策略可制造高强度和透明的3D打印微流体设备。

最近，在微流体应用中3D打印技术的使用已变得普遍。尽管这些技术使得能够以低成本，快速且容易地制造微流体装置，但是所制造的装置具有光学不透明性，从而限制了其用于显微成像的用途。这项研究调查了使用聚二甲基硅氧烷（PDMS）和打印机树脂作为夹层材料的粘合策略，以制造高强度光学透明3D打印的微流体设备。首先，我们使用立体光刻3D打印机制造了微流体结构。我们将3D打印的结构放置在夹层材料涂层的表面上。然后，我们要么将这些3D打印的结构放在涂层的幻灯片上，要么将它们转移到新的玻璃幻灯片上。我们实现了3D打印结构和玻璃基板之间的粘合，其中紫外线暴露于树脂，而高温则适用于PDMS夹层材料。研究了不同夹层材料厚度的粘结强度。我们还分析了使用不同键合策略制造的微流体装置的明场和荧光成像能力。对于使用传统的等离子活化PDMS-玻璃键合方法制造的微流控设备，我们的键合强度提高了两倍（9.1 bar），荧光灵敏度也相当。尽管立体光刻3D打印机允许制造尺寸低至〜600μm的封闭通道，但使用粘合剂夹层可以实现横截面为280×110μm2的单片透明微流体通道。此外，3D打印的微流控芯片可以使用树脂夹层成功地与Protein-G修饰的底物整合，以检测低至约30 ng / ml的荧光标记免疫球蛋白。因此，该策略可以应用于制造高强度且透明的微流控芯片，以用于包括生物传感在内的各种光学成像应用。