We present a high resolution, ultra-frugal printing of paper microfluidic devices using in-house paraffin formulation on a simple filter paper. The patterns printed using an office inkjet printer formed a selective hydrophobic barrier of 4 ± 1 µm thickness with a hydrophilic channel width of 275 µm. These printed patterns effectively confine common aqueous solutions and solvents, which was verified by solvent compatibility studies. SEM analysis reveals that the solvent confinement is due to pore blockage in the filter paper. The fabricated paper-based device was validated for qualitative assessment of Candida albicans (pathogenic fungi) by using a combination of L-proline β-naphthylamide as the substrate and cinnamaldehyde as an indicator. Our studies reveal that the pathogenic fungi can be detected within 10 min with the limit of detection (LOD) of 0.86 × 10⁶ cfu/mL. Owing to its simplicity, this facile method shows high potential and can be scaled up for developing robust paper-based devices for biomarker detection in resource-limited settings.

Graphic abstract

中文翻译：

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在纸上进行石蜡喷墨打印可对病原真菌进行低成本的即时诊断

我们提出了在内部简单的滤纸上使用内部石蜡配方对纸微流控设备进行的高分辨率，节俭打印。使用办公室喷墨打印机打印的图案形成了厚度为4±1 µm的选择性疏水性屏障，亲水通道宽度为275 µm。这些印刷图案有效地限制了常见的水溶液和溶剂，这已通过溶剂相容性研究得到证实。SEM分析表明，溶剂的限制是由于滤纸中的孔堵塞所致。经验证的人造纸制设备可用于白色念珠菌的定性评估（病原性真菌）通过结合使用L-脯氨酸β-萘酰胺作为底物和肉桂醛作为指示剂。我们的研究表明，可以在10分钟内检测到病原真菌，其检出限（LOD）为0.86×10 ⁶  cfu / mL。由于其简单性，这种简便的方法显示出很高的潜力，并且可以扩大规模，以开发功能强大的基于纸张的设备，以在资源受限的环境中进行生物标记检测。

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