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Updated: Feb 15, 2026

Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays
Published on: March 9, 2017
Microfluidic Paper-based Analytical Device for the Determination of Hexavalent Chromium by Photolithographic
Hitoshi Asano1, Yukihide Shiraishi2
1Center for Liberal Arts and Sciences, Tokyo University of Science, Yamaguchi.
Abstract:
This article describes a simple and inexpensive microfluidic paper-based analytical device (μPAD) for the determination of hexavalent chromium (CrVI) in water samples. The μPADs were fabricated on paper by photolithography using a photomask printed with a 3D printer and functionalized with reagents for a colorimetric assay. In the μPAD, CrVI reacts with 1,5-diphenylcarbazide to form a violet-colored complex. Images of μPADs were captured with a digital camera; then the red, green, and blue color intensity of each detection zone were measured using images processing software. The green intensity analysis was the best sensitive among the RGB color. A linear working range (40 - 400 ppm; R2 = 0.981) between the CrVI and green intensity was obtained with a detection limit of 30 ppm. All of the recoveries were between 94 and 109% in recovery studies on water samples, and good results were obtained.
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