Laser-polymerised fluidic channels for the manufacture of multiplexed paper-based diagnostic sensors

Abstract

Paper-based microfluidics is a rapidly progressing inter-disciplinary technology driven by the need for low-cost alternatives to conventional point-of-care diagnostic tools. For transport of reagents/analytes, such devices often consist of interconnected hydrophilic fluid-flow channels that are demarcated by hydrophobic barrier walls that extend through the thickness of the paper. Here, we present a laser-based fabrication procedure that uses laser-induced polymerisation of a photopolymer to produce the required fluidic channels in paper or other porous materials. Experimental results showed that the structures successfully guide the flow of fluids and also allow containment of fluids in wells, and hence the technique is suitable for fabrication of paper-based microfluidic devices.The minimum width for the hydrophobic barriers that successfully prevented fluid leakage was ~120 µm and the minimum width for the fluidic channels that can be formed was ~80 µm, the smallest reported so far for paper-based fluidic patterns. The patterns can be produced rapidly using simple low power c.w. laser sources at a writing speed of order 1 ms-1 and we have successfully demonstrated techniques for controlled delay, forward biased and multiplexed flow of several different fluids. We show our early results for diagnostic paper-based sensors for the detection of glucose and bovine serum albumin (BSA) using colorometric readout, which we believe makes the technique especially useful for mass-market applications, particularly in developing world situations where simplicity, cheapness and ready availability are the key parameters