Abstract
As a promising concept, microfluidic paper-based analytical devices (μPADs) have seen rapid development in recent years. In this study, a new method of fabricating μPADs by atom stamp printing (ASP) is proposed and studied. The advantages of this new method compared to other methods include its low cost, ease of operation, high production efficiency, and high resolution (the minimum widths of the hydrophilic channels and hydrophobic barriers are 328 and 312 μm, respectively). As a proof of concept, μPADs fabricated with the ASP method were used to detect different concentrations of Cu2+ via a colorimetric method. Moreover, combined with a distance-based detection method, these devices achieved a Cu2+ detection limit of down to 1 mg/L. In addition, a new paper-based solid–liquid extraction device (PSED) based on a three-dimensional (3D) μPAD with a “3 + 2” structure and a recyclable extraction mode was developed. Specifically, using the characteristics of paper filtration and capillary force, the device completed multiple extraction and filtration steps from traditional solid–liquid extraction processes with high efficiency. The developed PSED platform allows the detection of heavy metal ions much more cheaply and simply and with a faster response time at the point of care, and it has great promise for applications in food safety and environmental pollution in resource-limited areas.
Highlights
In the 1990s, the concept of a “lab on a chip (LOC)” was proposed based on the development of microfluidic technology[1,2]
To further demonstrate the versatility of our μPADs, we introduced an integrated device, which combined 3D μPADs and a homemade micropump to achieve integrated extraction and filtration, called a paper-based soil–liquid extraction device (PSED)
Resolution analysis of μPADs by the atom stamp printing (ASP) method Resolution is an important metric to evaluate the performance of μPADs
Summary
In the 1990s, the concept of a “lab on a chip (LOC)” was proposed based on the development of microfluidic technology[1,2]. In 2008, Abe et al.[17] completed the fabrication of μPADs by inkjet printing with “chemical sensing inks” and achieved a relatively high channel accuracy of 550 μm. Laser cutting has been the best way to achieve the highest accuracy of channel resolution on paper, which can reach 62 ± 1 μm and can be used on any paper with a hydrophobic surface coating[20], such as wax paper or parchment paper; this operation is more complex, and the paper needs further chemical treatment
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