Development of paper-based point-of-care biosensors by laser-based direct-write processes

Abstract

The demand for low-cost alternatives to conventional point-of-care (POC) diagnostic tools has led to significant developments in the field of microfluidics in porous materials. Several approaches have already been reported for fabricating fluidic devices in such materials, which include photolithography, inkjet printing, wax printing etc.

In this thesis, a new approach towards the fabrication of paper-based POC diagnostic sensors is proposed, which is a simple laser-based direct-write (LDW) procedure that uses polymerisation of a photopolymer to produce the required fluidic channels in porous substrates. Furthermore, this LDW technique is also further developed and explored for the introduction of a range of additional functionalities in paper-based microfluidic devices. Firstly, programmable flow control is enabled via two fluid delay mechanisms, namely, permeable barriers with variable porosity and impermeable barriers with variable depth. The generated flow delays can span times from minutes to over an hour. Secondly, the same LDW approach is also developed for stacking and sealing of multi-layer substrates, for assembly of backing layers for two-dimensional lateral flow devices (LFDs) and eventually for fabrication of three-dimensional devices.

In addition, we also report an idea of enabling fluidic gating in paper-based devices via triggerable wax barriers. The printed wax barrier acts as triggerable fluidic gates, which can be switched on demand via the application of local heating.

Finally, these LDW fabricated paper-based devices were validated via implementation of various clinical diagnostics and analytical chemistry assays using both artificial samples as well as real human bodily fluids.

Overall, a huge number of advantages have been established with this approach for both device fabrication and enabling additional functionalities. Thus, we believe that this technique could be an ideal choice for fabrication of paper-based microfluidic devices.

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Identifiers

ORCID for Robert Eason: orcid.org/0000-0001-9704-2204

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