A Facile Method to Fabricate an Enclosed Paper-Based Analytical Device via Double-Sided Patterning for Ionic...

Area of Science:

• Materials Science and Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Conventional microfluidic paper-based analytical devices (μPADs) suffer from sample evaporation and contamination due to their open-channel design.
• These limitations hinder their application as reliable analytical platforms, particularly for sensitive detection tasks.
• There is a need for enclosed μPAD designs to overcome these challenges and enhance analytical performance.

Purpose of the Study:

• To design and fabricate an enclosed three-dimensional (3D)-μPAD.
• To demonstrate its utility as a primary early analysis platform for ionic contaminants.
• To optimize fabrication parameters for creating enclosed microchannels using 3D printing and polydimethylsiloxane (PDMS) patterning.

Main Methods:

• Fabrication of a 3D-printed stamp mold for double-sided polydimethylsiloxane (PDMS) patterning.
• Controlled PDMS permeation onto a cellulose substrate to create hydrophobic barriers and enclosed channels.
• Optimization of stamp design (round shape, 10 mm inter-pattern distance) and patterning conditions (0.5 min contact time, 300 µm spacer height).

Main Results:

• Successful fabrication of enclosed 3D-μPADs with optimized parameters.
• Simultaneous colorimetric detection of Ni²⁺, Cu²⁺, Hg²⁺, and Cs⁺ ions within 3 minutes.
• Achieved limits of detection (LOD) as low as 0.016 ppm for Cs⁺, with high reliability (CV < 3%) across tested ion concentrations.

Conclusions:

• The enclosed 3D-μPAD effectively prevents sample evaporation and contamination, enhancing analytical reliability.
• This platform offers a promising solution for rapid, sensitive, and quantitative early detection of ionic contaminants.
• The developed 3D-μPAD technology has significant potential for applications in environmental and biological industries.