Perera A T K, Phan Dinh-Tuan, Pudasaini Sanam, Liu Yu, Yang Chun
Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
Biomicrofluidics. 2020 Jan 2;14(1):014103. doi: 10.1063/1.5133946. eCollection 2020 Jan.
Microfluidic paper-based analytical devices (μPADs) represent a modest and feasible alternative for conventional analytical methods. However, the inadequate sensitivity of these devices limits the possible applications of μPADs. In this scenario, inducing ion concentration polarization (ICP) on μPADs has shown promise to overcome this limitation by preconcentrating the analytes of interest. Here, we report a μPAD implementing ICP using an off-shelf Nafion® membrane as the perm selective membrane. Two types of devices with a geometrical configuration of a straight channel converging at the middle connecting to circular reservoirs at the end of channels were fabricated. The devices are comprised of a single input channel and an absorption channel. The Nafion membrane is attached to the absorption channel of the device, which is encased by heating with paraffin films at both sides to lower the electro-osmotic flow generated by an applied DC electric field that is needed for ICP. The field induced ICP enables obtaining a maximum concentration factor of more than 2000 folds for fluorescein sodium salt solution on the μPAD. Also, since evaporation of the sample solution was reported to be of great influence on the concentration factor, we analyze the effect of sample solution evaporation on sample preconcentration. Furthermore, our reported fabrication method for μPAD can lower the fabrication cost down to 0.3 USD. This device shows the potential to be developed for serving as a diagnostic and environmental monitoring platform.
基于微流控纸的分析装置（μPADs）是传统分析方法一种适度且可行的替代方案。然而，这些装置灵敏度不足限制了μPADs的可能应用。在这种情况下，在μPADs上诱导离子浓度极化（ICP）已显示出有望通过预富集目标分析物来克服这一限制。在此，我们报告一种使用现成的Nafion®膜作为渗透选择性膜来实现ICP的μPAD。制造了两种几何结构为直通道在中间汇聚并在通道末端连接圆形储液器的装置。这些装置由单个输入通道和一个吸收通道组成。Nafion膜附着在装置的吸收通道上，该通道两侧用石蜡膜加热包裹，以降低ICP所需施加的直流电场产生的电渗流。电场诱导的ICP能够在μPAD上使荧光素钠盐溶液获得超过2000倍的最大浓缩因子。此外，由于据报道样品溶液的蒸发对浓缩因子有很大影响，我们分析了样品溶液蒸发对样品预富集的影响。此外，我们报道的μPAD制造方法可将制造成本降低至0.3美元以下。该装置显示出有潜力被开发用作诊断和环境监测平台。
