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Programmable delay in paper-based devices using laser direct writing

Programmable delay in paper-based devices using laser direct writing
Programmable delay in paper-based devices using laser direct writing
Demand for low-cost alternatives to conventional medical diagnostic tools has been the driving force that has spurred significant developments in the diagnostics field. Paper-based fluidics, proposed by the Whitesides’ group in 2007 has been regarded as one such alternative, and consequently, this field has been progressing rapidly and a range of paper-based fluidic devices that implement different assays have since been demonstrated. Research into the development of methodologies that control, and in particular delay the flow of fluids in these devices is an urgently needed requirement that would enable greater functionalities in such paper-based devices.

In this work, to control fluid-flow, we report the use of a new approach that is based on the laser-based photo-polymerisation technique that we have reported earlier for the creation of fluidic patterns (channels/wells) in paper. The delay or slowing down, of the fluid-flow in a fluidic channel is achieved via the introduction of barriers aligned across the direction of the fluid-flow – in a fashion similar to how speed-bumps enable traffic-calming control on a road. The schematic in Figure 1a shows how the delay can be introduced via the creation/insertion of barriers which are solid and impermeable and by controlling the ‘depth’ of the solid/impregnable barriers (Figure 1) to allow for controlled leakage of the fluids under the barriers. The control over the depth of the barriers is obtained by simply adjusting the laser-writing parameters such as the output power and writing/scanning speed. We observe that solid/impregnable barriers of various depths decrease the fluid flow by a rate that is proportional to their depth. Having patterned these barriers at pre-defined locations in the fluidic channel, using a pulsed laser operating at 266nm (20Hz, 10ns) we have achieved flow-delays with a time span ranging from few minutes to over an hour. We have also performed a study to understand the influence of the number of barriers and their position on the flow-delay, and this is shown in Figure 2.

Since the channels and flow-delay barriers can be written via a common laser-writing procedure, this technique has a distinct advantage over certain other methods that require specialist operating environments, or custom-designed equipment to enable both these aspects. We believe this rapid and versatile technique is therefore suited for fabrication of ‘sample-in-read-out’ type automated paper-based microfluidic devices that can implement single/multistep analytical assays.
He, Peijun
2e303166-6aa5-4a09-b22e-440d96a54a9f
Katis, Ioannis
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Eason, Robert
e38684c3-d18c-41b9-a4aa-def67283b020
Sones, Collin
9de9d8ee-d394-46a5-80b7-e341c0eed0a8
He, Peijun
2e303166-6aa5-4a09-b22e-440d96a54a9f
Katis, Ioannis
f92dfb8f-610d-4877-83f6-fd26a571df12
Eason, Robert
e38684c3-d18c-41b9-a4aa-def67283b020
Sones, Collin
9de9d8ee-d394-46a5-80b7-e341c0eed0a8

He, Peijun, Katis, Ioannis, Eason, Robert and Sones, Collin (2016) Programmable delay in paper-based devices using laser direct writing. International Conference of Microfluidics, Nanofluidics and Lab-on-a-Chip, Dalian, China. 09 - 11 Jun 2016.

Record type: Conference or Workshop Item (Paper)

Abstract

Demand for low-cost alternatives to conventional medical diagnostic tools has been the driving force that has spurred significant developments in the diagnostics field. Paper-based fluidics, proposed by the Whitesides’ group in 2007 has been regarded as one such alternative, and consequently, this field has been progressing rapidly and a range of paper-based fluidic devices that implement different assays have since been demonstrated. Research into the development of methodologies that control, and in particular delay the flow of fluids in these devices is an urgently needed requirement that would enable greater functionalities in such paper-based devices.

In this work, to control fluid-flow, we report the use of a new approach that is based on the laser-based photo-polymerisation technique that we have reported earlier for the creation of fluidic patterns (channels/wells) in paper. The delay or slowing down, of the fluid-flow in a fluidic channel is achieved via the introduction of barriers aligned across the direction of the fluid-flow – in a fashion similar to how speed-bumps enable traffic-calming control on a road. The schematic in Figure 1a shows how the delay can be introduced via the creation/insertion of barriers which are solid and impermeable and by controlling the ‘depth’ of the solid/impregnable barriers (Figure 1) to allow for controlled leakage of the fluids under the barriers. The control over the depth of the barriers is obtained by simply adjusting the laser-writing parameters such as the output power and writing/scanning speed. We observe that solid/impregnable barriers of various depths decrease the fluid flow by a rate that is proportional to their depth. Having patterned these barriers at pre-defined locations in the fluidic channel, using a pulsed laser operating at 266nm (20Hz, 10ns) we have achieved flow-delays with a time span ranging from few minutes to over an hour. We have also performed a study to understand the influence of the number of barriers and their position on the flow-delay, and this is shown in Figure 2.

Since the channels and flow-delay barriers can be written via a common laser-writing procedure, this technique has a distinct advantage over certain other methods that require specialist operating environments, or custom-designed equipment to enable both these aspects. We believe this rapid and versatile technique is therefore suited for fabrication of ‘sample-in-read-out’ type automated paper-based microfluidic devices that can implement single/multistep analytical assays.

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More information

e-pub ahead of print date: 10 June 2016
Venue - Dates: International Conference of Microfluidics, Nanofluidics and Lab-on-a-Chip, Dalian, China, 2016-06-09 - 2016-06-11
Organisations: Optoelectronics Research Centre

Identifiers

Local EPrints ID: 400759
URI: http://eprints.soton.ac.uk/id/eprint/400759
PURE UUID: 7bbaeec7-aff4-40fd-af3e-8b9d043d329c
ORCID for Ioannis Katis: ORCID iD orcid.org/0000-0002-2016-557X
ORCID for Robert Eason: ORCID iD orcid.org/0000-0001-9704-2204

Catalogue record

Date deposited: 26 Sep 2016 10:25
Last modified: 16 Jun 2021 01:45

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Contributors

Author: Peijun He
Author: Ioannis Katis ORCID iD
Author: Robert Eason ORCID iD
Author: Collin Sones

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