Developing a rapid fabrication method for crack-free opal films is a significant challenge with broad applications. We developed a microfluidic platform known as the “filter paper-enhanced evaporation microfluidic chip” (FPEE-chip) for the fabrication of photonic crystal and inverse opal hydrogel (IOPH) films. The chip featured a thin channel formed by bonding double-sided adhesive poly(ethylene terephthalate) with a polymethyl methacrylate cover and a glass substrate. This channel was then filled with nanosphere colloids. The water was guided to evaporate rapidly at the surface of the filter paper, allowing the nanospheres to self-assemble and accumulate within the channel under capillary forces. Experimental results confirmed that the self-assembly method based on the FPEE-chip was a rapid platform for producing high-quality opal, with centimeter-sized opal films achievable in less than an hour. Furthermore, the filter paper altered the stress release mechanism of the opal films during drying, resulting in fewer cracks. This platform was proven capable of producing large-grain, crack-free opal films of up to 30 mm² in size. We also fabricated crack-free IOPH pH sensors that exhibited color and size responsiveness to pH changes. The coefficient of variation of the gray color distribution for crack-free IOPH ranged from 0.03 to 0.07, which was lower than that of cracked IOPH (ranging from 0.07 to 0.14). Additionally, the grayscale peak value in 1 mm² of the crack-free IOPH was more than twice that of the cracked IOPH at the same pH. The FPEE-chip demonstrated potential as a candidate for developing vision sensors.

中文翻译：

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利用滤纸增强蒸发芯片快速制造大颗粒蛋白石薄膜和光子晶体水凝胶传感器


开发无裂纹蛋白石薄膜的快速制造方法是具有广泛应用的重大挑战。我们开发了一种称为“滤纸增强蒸发微流控芯片”（FPEE-chip）的微流控平台，用于制造光子晶体和反蛋白石水凝胶（IOPH）薄膜。该芯片具有通过将双面胶聚对苯二甲酸乙二醇酯与聚甲基丙烯酸甲酯盖和玻璃基板粘合而形成的细通道。然后用纳米球胶体填充该通道。水被引导在滤纸表面快速蒸发，使纳米球在毛细管力的作用下自组装并积聚在通道内。实验结果证实，基于 FPEE​​ 芯片的自组装方法是生产高质量蛋白石的快速平台，在一小时内即可实现厘米级蛋白石薄膜。此外，滤纸改变了蛋白石薄膜在干燥过程中的应力释放机制，从而减少了裂纹。事实证明，该平台能够生产尺寸高达 30 毫米 ² 的大颗粒、无裂纹蛋白石薄膜。我们还制造了无裂纹 IOPH pH 传感器，该传感器表现出颜色和尺寸对 pH 变化的响应。无裂纹IOPH的灰度颜色分布变异系数范围为0.03至0.07，低于有裂纹​​IOPH的灰色分布系数（范围为0.07至0.14）。此外，在相同pH值下，无裂纹IOPH在1mm ² 处的灰度峰值是有裂纹IOPH的两倍以上。 FPEE 芯片展示了作为开发视觉传感器的候选芯片的潜力。