Comparative study on obtaining paper and thread-based microfluidics via simple fabrication techniques

Abstract

Microfluidic paper-based analytical devices (µPADs) and microfluidic thread-based analytical devices (µTADs) have recently been introduced as a new class of on-site monitoring devices. Creating hydrophilic channels with hydrophobic barriers on papers/threads produces µPADs/µTADs. Fabrication is a crucial step in creating durable µPADs/µTADs that can withstand various liquids and impact the device's performance. Fabrication materials with distinct physicochemical properties allow microfluidic systems with sophisticated functions to be customized for specific applications. We present flexible and low-cost fabrication methods for µPAD and µTAD platforms. Platform designs and fabrications were implemented using a trial-and-error method for various designs with varying parameters. All production methods presented in the method section were used in µPAD production. For comparison studies, only the dipping method was used in µTAD production due to its ease of application. In this study, we tried to reveal the strengths and weaknesses of the production techniques and the resulting microfluidic platforms. A leaching test was performed with water solutions containing red ink. The compatibility of the hydrophobic walls of the platforms was tested with several solvents (isopropanol, methanol, and acetone), deionized (DI) water, and phosphate buffer solution PBS and compared. Patterning paper with polydimethylsiloxane (PDMS), white glue, alkyl ketene dimer (AKD), beeswax, and paraffin are much more flexible and simpler than traditional photoresist-based fabrications. The advantages and disadvantages of fabrication techniques; solvent resistance and wicking behaviors of platforms were discussed in the last part. The fabricated microfluidic platforms can be functionalized and used in many areas where analytical tests are applied. Studies on diversifying channel geometries and increasing resolution need to be continued. It should be investigated which devices can be used to obtain qualitative and quantitative results. To make simple and cheap production techniques suitable for mass production, studies should be carried out from different branches.