• Clean Technology
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• v.28 no.4
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• pp.323-330
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• 2022

Microfluidic paper-based analytical devices (μPADs) have recently been in the spotlight for their applicability in point-of-care diagnostics and environmental material detection. This study presents a double-sided printing method for fabricating 3D-μPADs, providing simple and cost effective metal ion detection. The design of the 3D-μPAD was made into an acryl stamp by laser cutting and then coating it with a thin layer of PDMS using the spin-coating method. This fabricated stamp was used to form the 3D structure of the hydrophobic barrier through a double-sided contact printing method. The fabrication of the 3D hydrophobic barrier within a single sheet was optimized by controlling the spin-coating rate, reagent ratio and contacting time. The optimal conditions were found by analyzing the area change of the PDMS hydrophobic barrier and hydrophilic channel using ink with chromatography paper. Using the fabricated 3D-μPAD under optimized conditions, Ni²⁺, Cu²⁺, Hg²⁺, and pH were detected at different concentrations and displayed with color intensity in grayscale for quantitative analysis using ImageJ. This study demonstrated that a 3D-μPAD biosensor can be applied to detect metal ions without special analysis equipment. This 3D-μPAD provides a highly portable and rapid on-site monitoring platform for detecting multiple heavy metal ions with extremely high repeatability, which is useful for resource-limited areas and developing countries.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.141-144
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• 2006

An antibody layer was fabricated to detect Escherichia coli O157:H7. The micropattern of 16-mercaptohexadecanoic acid (16-MHDA) as alkylthiolate was formed on the gold surface by using the PDMS stamp with microcontact printing $({\mu}CP)$ techniques. In order to form antibody patterns on the template, protein G was chemically bound to the 16-MHDA patterns, and antibody was adsorbed on a self-assembled protein G layer. The formation of the 16-MHDA micropattern, self-assembled protein G layer and antibody pattern on Au substrate was confirmed by surface plasmon resonance (SPR) spectroscopy. Finally, the micropatterning method was applied to fabricate the antibody probe for detection of E. coli O157:H7, and monitoring of antigen by using this probe was successfully achieved.