Material jetting printing of high-precision curved surface circuits: from materials to applications

The structural mismatch between conventional flat circuits and the three-dimensional (3D) conformal requirements of curved integrated electronic systems. Hard-surfaced conformal circuit technology enables the direct printing of circuits onto product structures for integrated conformal manufacturing of electronic and mechanical components. However, achieving high-precision printing on complex surfaces presents challenges, such as 3D conformal adaptability between circuits and substrates, uniform deposition of micro- and nanoscale conductive features, and coordinated optimisation of electrical performance and mechanical reliability. This paper focuses on direct inkjet printing technology for fabricating highly precise, geometrically complex hard-surface circuits, analyzing the advances and bottlenecks in functional materials, processes, and applications. Tailoring ink rheology, interfacial energy, dynamic parameters, and post-processing can enhance the conductivity and resolution. Finally, this paper discusses the critical challenges in curved circuit fabrication related to dynamic deformation adaptability, cross-scale accuracy, and long-term reliability. These are examined through the lens of multi-scale modelling, intelligent closed-loop control, and heterogeneous material integration. Breakthrough directions are proposed, including inverse process design via machine learning and dynamic adaptive intelligent response strategies. Overall, this review consolidates the knowledge of hard-surfaced circuit manufacturing, highlights its transformative potential in aerospace, sensing, and human-computer interaction, and provides interdisciplinary foundations to address surface electronic integration.