Evaluation of a Range of Surface Modifications for the Enhancement of Lateral Flow Assays on Cyclic Polyolefin Micropillar Devices

We report the evaluation of a range of surface modifications for the formation of a stable, uniform, hydrophilic surface on cyclic polyolefin-based microfluidic devices. The surface modifications employed were oxygen plasma treatment alone, or in combination with polyelectrolyte (PE) modifications or chemical vapour deposition (CVD) of silicon dioxide as well as dextran modification. The surface modifications were characterised by atomic force microscopy (AFM), contact angle (CA) measurements and both quantitative and qualitative lateral flow measurements. It was demonstrated that the silicon dioxide and PE treatments produced the lowest CAs and therefore most hydrophilic surfaces, which was reflected in the improved lateral flow rates on this normally hydrophobic polymer. However, the non-uniformity of the PE coating as well as its reduced reproducibility and stability over time in comparison to the silicon dioxide coating meant that the silicon dioxide was the favoured surface modification.