<p>On-demand manufacturing of electronics is reshaping how functional devices are designed, fabricated, and deployed. At the forefront of this transformation are functional inks, which determine not only printability but also device performance, reliability, sustainability, and scalability. Despite significant progress in printing platforms, ink design and formulation remain a primary bottleneck for achieving high-performance and robust manufacturing systems. This perspective examines the physicochemical design principles that govern functional inks for printed electronics, with a particular focus on electrohydrodynamic printing. We highlight how advances in material chemistry, nanoparticle morphology, and two-dimensional and precursor-based material systems are rapidly expanding the design space for electronics, sensing, and energy-related devices. By linking ink composition, jetting physics, and device-level performance, this work outlines critical challenges and emerging opportunities for developing scalable, high performance, and sustainable on-demand electronics.</p> Graphical abstract <p>Electrohydrodynamic printing enables high-resolution patterning of functional inks, linking materials design, printing physics, and device performance for printed electronics.</p> <p></p>