Redesigning EWOD Interconnections: Inkjet-Printed PEDOT:PSS Electrodes with Enhanced Pad Access

EWOD fabrication is typically costly, requiring specialist microfabrication facilities, equipment and techniques like physical vapour deposition. Printed electronics methods like inkjet printing offer cheaper and faster alternatives to typical fabrication methods, and conductive polymers like PEDOT:PSS offer advantages in flexibility, cost, and transparency. We report a low-cost fabrication approach and characterise its performance against standard ITO-glass electrodes. Ink-on-paper electrodes and patterned-on-glass electrodes are restricted to a single plane, limiting the number of electrically independent electrodes on a single conductive layer. Our design and fabrication approach, employing inkjet printing and double-sided patterning, overcomes topological constraints, addressing both connectivity and cost. PEDOT:PSS is highly compatible with inkjet printing technology, and a single pass of PEDOT:PSS printing was sufficient to achieve the desired conductivity, offering a cost-effective solution for fabricating large, multilevel, flexible EWOD electrode arrays.