Colored wax-printed timers for two-dimensional and three-dimensional assays on paper-based devices

Chen Hsun Weng, Ming Yi Chen, Chi Hsiang Shen, Ruey Jen Yang

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


Microfluidic paper-based analytical devices (μPADs) are widely used for performing diagnostic assays. However, in many assays, time-delay valves are required to improve the sensitivity and specificity of the results. Accordingly, this study presents a simple, low-cost method for realizing time-delay valves using a color wax printing process. In the proposed approach, the time-delay effect is controlled through a careful selection of both the color and the saturation of the wax content. The validity of the proposed method is demonstrated by performing nitrite and oxalate assays using both a simple two-dimensional μPAD and a three-dimensional μPAD incorporating a colored wax-printed timer. The experimental results confirm that the flow time can be controlled through an appropriate selection of the color and the wax content. In addition, it is shown that nitrite and oxalate assays can be performed simultaneously on a single device. In general, the results presented in this study show that the proposed ?PADs provide a feasible low-cost alternative to conventional methods for performing diagnostic assays.

Original languageEnglish
Article number066502
Issue number6
Publication statusPublished - 2014 Nov 18

All Science Journal Classification (ASJC) codes

  • Biomedical Engineering
  • General Materials Science
  • Condensed Matter Physics
  • Fluid Flow and Transfer Processes
  • Colloid and Surface Chemistry


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