Introduction of in-line filtration in paper diagnostic device via a laser direct-write technique

Galanis, Panagiotis, He, Peijun, Katis, Ioannis, Thomas, M.R., Xianyu, Yunlei, Stevens, Moly, Eason, Robert and Sones, Collin (2018) Introduction of in-line filtration in paper diagnostic device via a laser direct-write technique. Biosensors 2018, Hyatt Regency Miami, Miami, United States. 12 - 15 Jun 2018. (In Press)

Abstract

With the promise of being a low-cost alternative to conventional in-vitro diagnostics, paper-based analytical devices have been researched extensively over the last decade to explore where their contributions can have the greatest impact in improving healthcare provisions. Filtration, which allows the interrogation of a complex liquid through size segregation of particulate content benefits a variety of applications such as protein digestion, separation of plasma from red blood cells etc. For such analytical devices, filtration is therefore regarded as a much-desired functionality, and several filtration techniques such as centrifugation, on-chip separation using comb-like filtering etc. have been described in the literature. However, all of these methods performed external to the diagnostic device require additional, undesired, sample pre-preparation steps.

Herein, we report a laser-based methodology that allows the fabrication of porous barriers within the flow-paths of a paper-based fluidic device for in-line sample-filtration. The barriers were produced via local-deposition of a photo-polymer that is subsequently polymerised by a laser source. Through adjustments of the deposition parameters, we can control the porosity of the barriers, which, when carefully designed and integrated within a fluidic channel (Fig.1), can act as filters that enable either the selective-filtration of (Fig.2) particles of a specific size, or the separation of (Fig.3) differently sized particles within a fluid travelling through the fluidic-channel.

We have successfully identified the barrier fabrication parameters and created devices that allow the filtration (Fig.2) of two different types of particles, Au-nanoparticles (with sizes 20, 100 and 200 nm) and latex beads (with sizes of 200 nm and 1 μm), and furthermore, we have created devices that allow separation of 1 μm latex beads from 20 nm Au-nanoparticles (Fig.3).

Overall, to our knowledge, this is the first example of a simple approach that allows in-line filtration of various constituents of a liquid-analyte within paper devices.

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Contributors

Author: Panagiotis Galanis

Author: Ioannis Katis

Author: Robert Eason

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