The Analyst · 2010 · 636 citations · 22 references
EngineeringBioengineeringBiomedical EngineeringBiomemsBiosensorsMicrofabricationMembrane FabricationMicrofluidic BiosensorsMicrofluidic Device FabricationMicrofluidic DevicesMicrofluidic SystemsMicrofluidicsElectrochemical MeasurementsFabricationMicrofluidic FabricationPaper-based Analytical DevicesPaper-based BiosensorsPaper-based Microfluidic BiosensorsPaper-based MicrofluidicsPaper-based Microfluidics Fabrication
Wax screen‑printing is presented as a low‑cost, simple, and rapid method for fabricating paper‑based microfluidic devices. The method involves rubbing solid wax through a screen onto paper filters, melting it on a hot plate to form hydrophobic barriers, optimizing barrier width and heating parameters, comparing the technique to photolithography, and applying the devices for simultaneous glucose and iron detection. The technique achieves minimum hydrophilic channel and hydrophobic barrier widths of 650 µm and 1300 µm, produces very low background relative to photolithography, and successfully enables simultaneous determination of glucose and total iron in serum, demonstrating its ease, low cost, and suitability for developing countries.
Wax screen-printing as a low-cost, simple, and rapid method for fabricating paper-based microfluidic devices (µPADs) is reported here. Solid wax was rubbed through a screen onto paper filters. The printed wax was then melted into the paper to form hydrophobic barriers using only a hot plate. We first studied the relationship between the width of a hydrophobic barrier and the width of the original design line. We also optimized the heating temperature and time and determined the resolution of structures fabricated using this technique. The minimum width of hydrophilic channel and hydrophobic barrier is 650 and 1300 µm, respectively. Next, our fabrication method was compared to a photolithographic method using the reaction between bicinchoninic acid (BCA) and Cu1+ to demonstrate differences in background reactivity. Photolithographically defined channels exhibited a high background while wax printed channels showed a very low background. Finally, the utility of wax screen-printing was demonstrated for the simultaneous determination of glucose and total iron in control human serum samples using an electrochemical method with glucose oxidase and a colorimetric method with 1,10-phenanthroline. This study demonstrates that wax screen-printing is an easy-to-use and inexpensive alternative fabrication method for µPAD, which will be especially useful in developing countries.
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Andres W. Martinez, Scott T. Phillips, Emanuel Carrilho et al. · Analytical Chemistry · 2008 · 1.4K citations · Full text