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Related Experiment Video

Updated: May 13, 2026

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

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Published on: November 22, 2016

Improved sensitivity in paper-based microfluidic analytical devices using a pH-responsive valve for nitrate analysis.

Lucas R Sousa¹, Nikaele S Moreira², Bárbara G S Guinati²

¹Departamento de Química Biológica e IQUIBICEN -CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA), CABA, Argentina; Instituto de Química, Universidade Federal de Goiás, 74690-900, Goiânia, GO, Brazil.

|June 15, 2024

Summary

This summary is machine-generated.

Chitosan pH-responsive valves precisely control fluid flow in microfluidic paper-based analytical devices (μPADs). This innovation enables controlled reaction times for applications like nitrate determination in water samples.

Keywords:

Chitosan Colorimetric response Flow control pH-responsive valve μPADs

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Area of Science:

Microfluidics
Analytical Chemistry
Materials Science

Background:

Microfluidic paper-based analytical devices (μPADs) offer portable and cost-effective diagnostics.
Precise control of fluid flow is crucial for sequential reactions and kinetic studies in μPADs.
Existing flow control methods can be complex or incompatible with certain analytical conditions.

Purpose of the Study:

To develop and evaluate chitosan-based pH-responsive valves for precise lateral flow control in μPADs.
To demonstrate the application of these valves in a nitrate determination assay.
To assess the compatibility and impact of the valves on analytical performance.

Main Methods:

Fabrication of μPADs using wax printing.
Creation of pH-responsive valves using a chitosan-acetic acid solution.
Integration of valves into μPADs for controlled flow and reaction timing.
Nitrate determination using the Griess reaction with controlled conversion time.

Main Results:

Chitosan valves successfully controlled lateral flow in μPADs.
Valves opened in acidic solutions (pH > 4) without affecting flow rate or colorimetric analysis.
Demonstrated successful nitrate determination in water samples with a linear range of 10-100 μmol L⁻¹ and a detection limit of 5.4 μmol L⁻¹.
Valves enabled increased conversion time for nitrate to nitrite, improving assay performance.

Conclusions:

Chitosan pH-responsive valves are a valuable tool for precise flow control in μPADs.
This technology enables controlled kinetics for multi-step analytical procedures.
The developed μPADs with chitosan valves show potential for diverse analytical chemistry applications, including environmental monitoring.