title: Method for fabrication of paper-based microfluidic devices by alkylsilane self-assembling and UV/O3-patterning.
abstract: This work presents a novel and facile method for fabricating paper-based microfluidic devices by means of coupling of hydrophobic silane to paper fibers followed by deep UV-lithography. After filter paper being simply immersed in an octadecyltrichlorosilane (OTS) solution in n-hexane for 5 min, the hydrophilic paper became highly hydrophobic (water contact angle of about 125°) due to the hydrophobic OTS molecules were coupled to paper's cellulose fibers. The hydrophobized paper was then exposed to deep UV-lights through a quartz mask that had the pattern of the to-be-prepared channel network. Thus, the UV-exposed regions turned highly hydrophilic whereas the masked regions remained highly hydrophobic, generating hydrophilic channels, reservoirs and reaction zones that were well-defined by the hydrophobic regions. The resolution for hydrophilic channels was 233 ± 30 μm and that for between-channel hydrophobic barrier was 137 ± 21 μm. Contact angle measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform-infrared (ATR-FT-IR) spectroscopy were employed to characterize the surface chemistry of the OTS-coated and UV/O(3)-treated paper, and the related mechanism was discussed. Colorimetric assays of nitrite are demonstrated with the developed paper-based microfluidic devices.
authors.affiliation: Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin'gang Campus, Hangzhou 310058, China. heqh@zju.edu.cn
authors.forename: Qiaohong
authors.initials: Q
authors.lastname: He
authors.forename: Cuicui
authors.initials: C
authors.lastname: Ma
authors.forename: Xianqiao
authors.initials: X
authors.lastname: Hu
authors.forename: Hengwu
authors.initials: H
authors.lastname: Chen