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Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays
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Fully inkjet-printed distance-based paper microfluidic devices for colorimetric calcium determination using
Hiroyuki Shibata1, Yuki Hiruta1, Daniel Citterio1
1Department of Applied Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. citterio@applc.keio.ac.jp.
The Analyst
|December 19, 2018
Summary
New inkjet-printed paper devices offer a user-friendly, low-cost method for determining calcium ions (Ca2+) in water. These devices provide accurate, naked-eye results, improving on existing water quality testing tools.
Area of Science:
- Analytical Chemistry
- Materials Science
- Environmental Science
Background:
- Accurate calcium ion (Ca2+) determination is crucial for assessing water hardness.
- Existing on-site analysis methods often lack user-friendliness and sensitivity.
- Microfluidic paper-based analytical devices (μPADs) offer potential for portable and cost-effective diagnostics.
Purpose of the Study:
- To develop fully inkjet-printed, low-cost μPADs for naked-eye colorimetric determination of Ca2+ in water.
- To enable simple, equipment-free on-site analysis of calcium ions in drinking and tap water.
- To improve sensitivity and user-friendliness compared to current Ca2+ detection methods.
Main Methods:
- Fabrication of μPADs using a standard desktop thermal inkjet printer for reagent deposition.
- Modification of detection channels with ionophore-doped ion-selective optode nanospheres (nano-optodes).
- Visual readout based on the length of the color-changed detection channel for Ca2+ quantification.
Main Results:
- Demonstrated successful inkjet printing of μPADs for Ca2+ detection.
- Achieved a detectable Ca2+ concentration range of 0.05–5 mmol L−1, aligning with ISO and WHO guidelines.
- Established a naked-eye detection limit of 0.05 mmol L−1, surpassing previous paper-based devices.
- Quantified Ca2+ in real water samples with an error margin within 15% compared to complexometric titration.
Conclusions:
- Inkjet-printed μPADs utilizing nano-optodes are effective for sensitive and reproducible Ca2+ determination.
- These devices offer a user-friendly, equipment-free solution for on-site water quality monitoring.
- The developed technology provides a viable alternative for accessible calcium analysis in various water sources.
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