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Micromachines 2017, 8(8), 242; doi:10.3390/mi8080242

Characterization of Reagent Pencils for Deposition of Reagents onto Paper-Based Microfluidic Devices

Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 93401, USA
Authors to whom correspondence should be addressed.
Received: 2 July 2017 / Revised: 29 July 2017 / Accepted: 1 August 2017 / Published: 5 August 2017
(This article belongs to the Special Issue Paper Microfluidics: Fundamental Studies and Applications)
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Reagent pencils allow for solvent-free deposition of reagents onto paper-based microfluidic devices. The pencils are portable, easy to use, extend the shelf-life of reagents, and offer a platform for customizing diagnostic devices at the point of care. In this work, reagent pencils were characterized by measuring the wear resistance of pencil cores made from polyethylene glycols (PEGs) with different molecular weights and incorporating various concentrations of three different reagents using a standard pin abrasion test, as well as by measuring the efficiency of reagent delivery from the pencils to the test zones of paper-based microfluidic devices using absorption spectroscopy and digital image colorimetry. The molecular weight of the PEG, concentration of the reagent, and the molecular weight of the reagent were all found to have an inverse correlation with the wear of the pencil cores, but the amount of reagent delivered to the test zone of a device correlated most strongly with the concentration of the reagent in the pencil core. Up to 49% of the total reagent deposited on a device with a pencil was released into the test zone, compared to 58% for reagents deposited from a solution. The results suggest that reagent pencils can be prepared for a variety of reagents using PEGs with molecular weights in the range of 2000 to 6000 g/mol. View Full-Text
Keywords: paper; diagnostics; microfluidic paper-based analytical devices (microPADs); pencil; wear; colorimetry paper; diagnostics; microfluidic paper-based analytical devices (microPADs); pencil; wear; colorimetry

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Liu, C.H.; Noxon, I.C.; Cuellar, L.E.; Thraen, A.L.; Immoos, C.E.; Martinez, A.W.; Costanzo, P.J. Characterization of Reagent Pencils for Deposition of Reagents onto Paper-Based Microfluidic Devices. Micromachines 2017, 8, 242.

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