Fabrication of Paper-based Microfluidic Devices by Octadecyltrichlorosilane Self-assembling and Uv-patterning

Paper-based microfluidic devices are emerging as a new technology for simple, low-cost, portable, and disposable diagnostic and monitoring platform. This article presents a novel method for fabricating microfluidic devices on paper by means of octadecyltrichlorosilane self-assembling and UV/O3-patterning. The hydrophilic filter paper was uniformly coated with a hydrophobic layer of octadecyltrichlorosilane (OTS) by dipping the paper into an OTS-hexane solution. The coated OTS layer was then treated with UV/O3 through a patterned quartz mask, generating hydrophobic barriers that define hydrophilic fluid channels, reservoirs and reaction zones. Contact angle measurements, XPS and ATR-FT-IR spectra confirmed that OTS self-assembled layer (OTS-SAL) was chemically immobilized on the filter paper surface and that the monolayer was degraded after UV/O3 treatment. The widths of the prepared hydrophilic channels and hydrophobic barriers could be as small as 80 μm and 130 μm, respectively. Colorimetric assays of nitrite ions were demonstrated with the developed paper-based microfluidic devices.