Signal amplification in a microfluidic paper-based analytical device (µ-PAD) by confinement of the fluidic flow

Seoyeon Choi, Jung Hyun Lee, Bong Seop Kwak, Young Woo Kim, Joon Sang Lee, Jong Soon Choi, Hyo Il Jung

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


This is a one-step POC biosensor that guarantees rapid assay times, low-cost analysis, simple handling, stability, and is easy to mass product. However, it has several drawbacks such as limited sample volume and relatively low sensitivity. To overcome these disadvantages, we have designed and fabricated the µ-PAD to confine fluid flow by creating a hydrophobic channel in the paper to improve the sensitivity. The channel pattern was drawn by a computer-aided design program and directly printed by a commercially available wax printer which generates the hydrophobic channel pattern. While maintaining a constant sample, absorption, and conjugation pad, the width of the detection pad was reduced from 5 mm to 2 mm at intervals of 1 mm. The intensity of bands from the single- and double-orifice patterns increased identically compared with the device with no orifice. The relative intensity of the signal bands increased from 141 to 158. Also, numerical simulation was performed to validate the experimental result by using lattice Boltzmann method. We observed that the sensitivity was enhanced at a specific detection pad width (3 mm). Therefore, our simple structural change of the channel led to improve the colorimetric intensity. Cortisol, which is a known stress biomarker, was used to validation the device, an enhanced signal was obtained indicating that our device can be used for the detection psychological stress in humans.

Original languageEnglish
Pages (from-to)116-123
Number of pages8
JournalBiochip Journal
Issue number2
Publication statusPublished - 2015 Jun 27

Bibliographical note

Publisher Copyright:
© 2015, The Korean BioChip Society and Springer-Verlag Berlin Heidelberg.

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Electrical and Electronic Engineering


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