Paper-Based Microfluidics: Fabrication Technique and Dynamics of Capillary-Driven Surface Flow

Abstract

Paper-based devices provide an alternative technology for simple, low-cost, portable, and disposable diagnostic tools for many applications, including clinical diagnosis, food quality control, and environmental monitoring. In this study we report a two-step fabrication process for creating two-dimensional microfluidic channels to move liquids on a hydrophobized paper surface. A highly hydrophobic surface was created on paper by TiO2 nanoparticle coating using a high-speed, roll-to-roll liquid flame spray technique. The hydrophilic pattern was then generated by UV irradiation through a photomask utilizing the photocatalytic property of TiO2. The flow dynamics of five model liquids with differing surface tensions 48-72 mN·m(-1) and viscosities 1-15 mN·m(-2) was studied. The results show that the liquid front (l) in a channel advances in time (t) according to the power law l=Zt0.5 (Z is an empirical constant which depend on the liquid properties and channel dimensions). The flow dynamics of the liquids with low viscosity show a dependence on the channel width and the droplet volume, while the flow of liquids with high viscosity is mainly controlled by the viscous forces.

A Review of Femtosecond‐Laser‐Induced Underwater Superoleophobic Surfaces

“…This phenomenon is named anisotropic wettability. The anisotropic wettability has a wide range of applications in selectively self‐cleaning, microfluidics, liquid pumps, droplet manipulation, smart devices, etc . Although the in‐air anisotropic water wettability has been achieved on various textured substrates, the report related to the anisotropic wettability of an oil droplet is still limited …”

“…Superhydrophobic surface is the earliest and the most widely studied interface in the field of superwettability because of its remarkable water repellence . Inspired by the superhydrophobicity of lotus leaf, thousands of artificial superhydrophobic surfaces have been fabricated, and those surfaces are wildly applied in self‐cleaning coatings, microdroplets manipulation, oil/water separation, anticorrosion, antifog/ice/snow, drag reduction, antifouling, cell engineering, water collection, microfluidics, lab chips, etc. After more than 20 years of development, both the basic theory and the fabrication technologies for superhydrophobic surfaces have reached a high level.…”

Liquid Flame Spray—A Hydrogen-Oxygen Flame Based Method for Nanoparticle Synthesis and Functional Nanocoatings

“…printability (Valtakari, et al, 2013) and microfluidistic design on roll-to-roll materials (Songok, et al, 2014;Valtakari et al, 2016). Also, hydrophobisation of the surface of wood materials is an important field (Moghaddam et al, 2013;Moghaddam et al, 2014), where direct nanoparticle deposition from the LFS has also been applied successfully (Moghaddam et al, 2015;Moghaddam et al, 2016).…”

Paper and Fiber-Based Bio-Diagnostic Platforms: Current Challenges and Future Needs

“…Fabrication of these platforms involves a wide variety of techniques, including plotting [13,14], wax-printing [15][16][17][18][19], inkjet-printing [20,21], flexographic printing [22], computer-controlled knife cutting [23], laser cutting [24,25], vapor-phase polymer deposition [26][27][28], photolithography [29][30][31][32][33][34], spraying [35], electrospinning [5,6,36] and coating [37], among others (Table 1) [2,21]. Different aspects of paper-based bio-diagnostic devices, including fabrication strategies, applications for the recognition of various biomolecular entities, the storability as well as the marketability of the paper-based products have been extensively reviewed [2,3,21,[38][39][40][41].…”