Laser patterned nitrocellulose-based microfluidic devices: Applications in fluid manipulation and immunoassay

Abstract

This work describes a new fabrication method to produce nitrocellulose-based microfluidic devices using CO2 laser ablation. This method requires only two simple steps: thermal bonding of a nitrocellulose membrane to a waxy film, and selective ablation of the membrane. The hollow microstructures created by selective ablation offer robust fluid barriers. With the optimized laser power and laser speed, two-dimensional fluid flow devices (2D) can be fabricated with fluid barrier width of 117 ± 11 µm and narrowest channel width of 81 ± 11 µm. This simple yet high resolution method can also be used for fabrication of a three-dimensional fluid flow device (3D) by simply bonding a stack of fabricated 2D devices. Fluidic delay and mixing tools in form of micropillar structures were created concurrently to device fabrication using the CO2 laser ablation. The phenomena of the fluidic delay and mixing were also evaluated by mathematical simulation which showed that micropillar structures not only delay the flow but also lead it into different directions and velocities causing passive fluidic mixing. A new nitrocellulose well plate fabricated using this method exhibited flexibility of device fabrication, superior sensitivity, less reagent consumption, and shorter analysis time than the conventional well plate.