Department of Bioengineering, University of California, Riverside, Riverside, CA, 92521, USA.
Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA, 92521, USA.
Biosens Bioelectron. 2021 May 15;180:113090. doi: 10.1016/j.bios.2021.113090. Epub 2021 Feb 19.
Paper-based microfluidic devices are an attractive option for developing low-cost, point-of-care diagnostic tools. To incorporate more complex assays into paper, these devices must become more sophisticated, through the sequential delivery of different liquids or reagents without user intervention. Many flow control strategies focus on slowing the fluid down. However, this can lead to increased assay times and sample loss due to evaporation. We report the use of a CO laser to create etched grooves on paper to accelerate wicking speeds in paper-based microfluidic devices. We explored different laser settings to determine the optimal configuration. Our findings showed that simply cutting a slit into the paper created the fastest wicking channels. The slit acted as a macro capillary, allowing fluid to bypass the paper and speed it up. Further studies determined an ideal groove pitch of 0.75 mm (spacing in between grooves) for a paper channel. Additional experiments documented how sealing grooved channels with different adhesives can influence wicking. Overall, sealing the channels with tape made them wick faster. However, sealing methods such as lamination had a negative effect on wicking. Laser-etched grooves were successfully used to design a fluid-handling architecture for a chemiresistive paper-based biosensor. The grooves facilitated rapid, sequential delivery of sample and wash buffer. Human serum albumin spiked in phosphate buffer, artificial urine, and artificial saliva was successfully detected at as low as 15 pM. Etching grooves in paper is a simple process that requires no additional materials or chemicals, allowing single-step fabrication of paper-based microfluidic channels.
基于纸张的微流控器件是开发低成本、即时诊断工具的理想选择。为了在纸张中纳入更复杂的检测，这些器件必须变得更加复杂，通过顺序输送不同的液体或试剂而无需用户干预。许多流量控制策略侧重于降低流体速度。然而，这可能会导致由于蒸发而导致检测时间延长和样本损失。我们报告了使用 CO 激光在纸张上创建蚀刻槽以加速基于纸张的微流控器件中的吸液速度。我们探索了不同的激光设置以确定最佳配置。我们的研究结果表明，只需在纸张上切一个狭缝就可以创建最快的吸液通道。狭缝充当宏观毛细管，允许流体绕过纸张并加速。进一步的研究确定了纸张通道的理想槽距为 0.75 毫米（槽之间的间距）。其他实验记录了用不同的粘合剂密封槽道会如何影响吸液。总体而言，用胶带密封通道会使它们更快地吸液。然而，层压等密封方法对吸液有负面影响。激光蚀刻的槽成功地用于设计基于化学电阻的纸基生物传感器的流体处理结构。这些槽有助于快速、顺序地输送样品和洗涤缓冲液。成功地以低至 15 pM 的浓度检测了磷酸盐缓冲液、人工尿液和人工唾液中添加的人血清白蛋白。在纸张上蚀刻槽是一个简单的过程，不需要额外的材料或化学物质，允许一步制造基于纸张的微流控通道。
