Paper-based microfluidic device is widely used in analytical and clinical diagnostics and has the advantages of low-cost, free-shape patterning, and power-free fluid transport by capillary action. In particular, nitrocellulose (NC) membrane is widely used for microfluidic device due to several merits such as cost-effectiveness, outstanding transport property and immobilizability of various proteins. For patterning of fluidic channel, wax printing method is generally used because the process is simple and easy to conduct. However, wax printing requires high curing temperature which results in severe deformation of NC membrane and it is difficult to fabricate well defined patterns because it is hard to control the wax diffusion.
In this work, we developed a simple fabrication method of NC membrane fluidic channel by using single printing process without thermal treatment. We patterned the NC membrane by wet etching process using Propylene Glycol Methyl Ether Acetate (PGMEA). For screen printing, we formulated PGMEA paste by mixing with precipitated silica. Fluidic channel was completed with screen printing and drying at room temperature. Dimensions of fabricated fluidic channel were nearly same that of initially designed patterns because the barrier wall formed by dissolved residues blocked diffusion of PGMEA paste.
Based on the simple patterning method, We have successfully fabricated multiple channels and verified uniform fluid flow in the each channel. We evaluated the NC membrane fluidic channel by colorimetric assay based on enzymatic reactions. For multiple colorimetric assay, we used the multiple channels and examined the simultaneity of the sensor.