Microfluidic flow modulation with digitized sizing pattern in Xuan paper-based analytical devices

Paper-based microfluidics in sweat detection: from design to application

“…58 Hsiu-Yang Tseng et al successfully developed programmable wicking profiles by alternating coated and uncoated zones with a solution composed of potassium alum and animal glue, which is a sizing material used in the fabrication of calligraphy Xuan paper. 59 Bahram Hemmateenejad et al reported a three-dimensional origami paper-based analytical device (3D-mu PAD) for ABO and Rh blood type detection using a three-dimensional origami microfluidic technology, using alkyl ketene dimer (AKD) ink for hydrophobic design. 60 Chemical modification presents a more stable state whereas physical blocking, especially wax printing, shows great potential in manufacture.…”

Mechanically Compressed Barriers Improve Paper-Based Lateral Flow Assay Sensitivity for COVID-19 Nucleic Acid Detection

“…To improve the sensitivity of LFA technology, various chemical and physical approaches have been reported. In the case of chemical modifications, increasing the electrolyte strength, modification of nitrocellulose (NC) membrane with cellulose nanofibers, addition of chitosan, use of spin-enhanced nanodiamond, self-assembling of gold nanoparticles following the layer-by-layer concept, using potassium alum and animal glue as sizing materials for creating barriers, and laser-patterned geometric barriers influencing the flow dynamics by increasing binding time are few among many other ways. In contrast to chemical modifications, some easy and convenient physical methods are also prominent for LFA sensitivity improvement, such as increasing the sample concentration by paper-based dialysis, use of CO 2 laser to create narrow flow path, and laser-direct write (LDW) technique, which is responsible for lowering the flow rate of liquid photopolymers, and the detection pad width and test line position impact the flow velocity and reaction rate kinetics affecting the limit of detection (LOD) and test-line color intensity …”