Abstract
Since the monumental work conducted by Whitesides et al. in 2007, research and development of paper-based microfluidics has been widely carried out, with its applications ranging from chemical and biological detection and analysis, to environmental monitoring and food-safety inspection. Paper-based microfluidics possesses several competitive advantages over other substrate materials, such as being simple, inexpensive, power-free for fluid transport, lightweight, biodegradable, biocompatible, good for colorimetric tests, flammable for easy disposal of used paper-based diagnostic devices by incineration, and being chemically modifiable. Myriad methods have been demonstrated to fabricate paper-based microfluidics, such as solid wax printing, cutting, photolithography, microembossing, etc. In this study, fabrication of paper-based microfluidics was demonstrated by spray on the printed paper. Different from the normally used filter papers, printing paper, which is much more accessible and cheaper, was utilized as the substrate material. The toner was intended to serve as the mask and the patterned hydrophobic barrier was formed after spray and heating. The processing parameters such as toner coverage on the printing paper, properties of the hydrophobic spray, surface properties of the paper, and curing temperature and time were systematically investigated. It was found that, after repetitive printing four times, the toner was able to prevent the hydrophobic spray (the mixture of PDMS and ethyl acetate) from wicking through the printing paper. The overall processing time for fabrication of paper-based microfluidic chips was less than 10 min and the technique is potentially scalable. Glucose detection was conducted using the microfluidic paper-based analytical devices (µPADs) as fabricated and a linear relationship was obtained between 1 and 10 mM.
Highlights
As the first microscale gas chromatography system was manufactured in 1979, it heralded the beginning of microfluidics as a field of its own [1]
As for the flow in the microfluidic paper-based analytical devices, it was placed under the microscope (SMZ-745T, Nikon, Tokyo, Japan) and the ink solution was dispensed in the reservoir at one end
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Summary
As the first microscale gas chromatography system was manufactured in 1979, it heralded the beginning of microfluidics as a field of its own [1]. Utilization of microfluidic platform for numerous applications ranging from point-of-care diagnostics, rapid test, forensics, food-safety inspection, environmental monitoring, and biotechnology has been extensively explored [2,3,4,5,6,7,8]. Compared to the conventional analytical approaches, microfluidics provides several merits such as fast response, high throughput, low reagent consumption, reduced waste product, high sensitivity, and great portability. Different substrate materials such as silicon, glass, polymer, and elastomer [9,10] have been exploited to construct the microfluidic devices, paper stands out as an attractive alternative because it is low-cost and ubiquitous [11]. The use of a paper device was first demonstrated by Müller and Clegg dating back to 1949 [14], it was not until 2007 that paper-based microfluidics regained attention, thanks to the work conducted by Whitesides’s group
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