Design of a Printer–Based Line Dispenser for Lateral Flow Assay Fabrication

Lateral flow assay (LFA) applications are crucial in the global healthcare system, but developing countries face problems in LFA research and manufacture. Accessibility to high-tech and expensive reagent line dispensers is one of the major issues. Although low-cost designs have been proposed, achieving a substantial outcome and flexible control remains a challenge. This study aims to investigate an affordable and efficient dispensing system that meets laboratory criteria. The study uses an EPSON piezoelectric inkjet printer with biomaterial-friendly printing techniques to dispense antibody solutions. A computational fluid mechanic simulation model of the printing nozzle was built using COMSOL Multiphysics for droplet formation investigation. To reduce printing consumption, the dead volume inside the cartridge was eliminated by resin for low-volume printing. Modifications were made in the printer file to control the dimension and density of the line, including dot size, dot color, and dot distribution matrix. The bandwidths of the dispensed lines were observed and measured under the microscope, and the intensity distributions were evaluated by the ImageJ software. The simulation model generated a 60 pl droplet out of a nozzle within a 20 μs time frame. The minimum inlet volume for the printing process was about 1 ml. All the dispensed lines were well-shaped, with an average error of 4.26% on the biggest lines. The intensity distribution graphs showed that lines from 1.5 to 1.7 mm bandwidth were the most uniform results. This study demonstrates that a commercial desktop printer can be transformed into a reagent line dispenser.