Fabrication of paper-based gradient generators.

Abstract

Paper-based microfluidic devices are one of the most promising applications of microfluidics because of the cheap cost of materials and fabrication, reduced sample and reagent consumption and device portability. Such devices would be ideal for use in locations with limited medical resources, like in developing countries or during military field assignments. This project explores the use of paper-based microfluidic devices as a gradient generator. Testing against a series of varying concentrations is often necessary in chemical analyses. Gradient profiles are also important for the study of cellular responses. Using paper-based microfluidic devices could present a strategy for the development of high throughput chemical analyses and portable point-of-care diagnostic tools. A device is proposed here consisting of a paper chip sandwiched between two layers of PDMS and secured together between plastic mounting plates with screws. Potassium ferricyanide and red food dye were used to successfully generate a linear concentration gradient. These coloured solutions underwent a series of dilutions as the fluid streams split and recombined in the microfluidic network. The greyscale intensities of the outlet reservoirs were analysed using imaging software, and plotted to produce a liner graph. The next step would be to determine if gradients can also be successfully generated using cell culture mediums and various growth factors.