Inkjet Printed Polyelectrolyte Patterns for Analyte Separation on Microfluidic Paper-based Analytical Devices

Paper-based microfluidic devices can provide practical analytics platforms for applications such as point-of-care medical diagnostics. However, immobilisation or separation of analytes on such devices has received limited
attention so far. This study introduces inkjet printed polyelectrolyte patterns as possible platforms for immobilisation of cationic and anionic compounds through surface charge interaction. Both anionic (sodium polyacrylate) and cationic (polydiallyldimethylammonium chloride) polyelectrolytes were inkjet printed on a custom designed pigment coating, having fine particle internal pore structure to ensure close proximity between the analytical sample and modified pore walls. Printed polyelectrolyte patterns were themselves poorly
visible both under ordinary and UV light. In a proof of principle test, a controllable degree of separation of anionic dyes from aqueous solution passing through a printed cationic polyelectrolyte region could be observed.