Engineering fluidic delays in paper-based devices using laser direct-writing

He, P.J.W., Katis, I.N., Eason, R.W. and Sones, C.L. (2015) Engineering fluidic delays in paper-based devices using laser direct-writing. Lab on a Chip, 15 (20), 4054-4061. (doi:10.1039/c5lc00590f).

Abstract

We report the use of a new laser-based direct-write technique that allows programmable and timed fluid delivery in channels within a paper substrate which enables implementation of multi-step analytical assays. The technique is based on laser-induced photo-polymerisation, and through adjustment of the laser writing parameters such as the laser power and scan speed we can control the depth and/or the porosity of hydrophobic barriers which, when fabricated in the fluid path, produce controllable fluid delay. We have patterned these flow delaying barriers at pre-defined locations in the fluidic channels using either a continuous wave laser at 405nm, or a pulsed laser operating at 266nm. Using this delay patterning protocol we generated flow delays spanning from minutes to over an hour. Since the channels and flow delay barriers can be written via a common laser-writing process, this is a distinct improvement over other methods that require specialist operating environments, or custom-designed equipment. This technique can therefore be used for rapid fabrication of paper-based microfluidic devices that can perform single or multistep analytical assays.

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Contributors

Author: I.N. Katis

Author: R.W. Eason

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