Multimaterial Hybrid Additive Manufacturing of Smart Polymer Structures with Embedded Electronics

Additive manufacturing (AM) provides a promising route for integrating electronic functionalities into polymer structures. However, existing approaches often rely on strong chemicals, post-processing, or assembly steps that limit design flexibility, manufacturing efficiency, and electrical reliability. This study presents a multimaterial hybrid AM strategy that integrates fused filament fabrication with cold spray additive manufacturing (CSAM) to fabricate polymer structures with embedded functionality. Tin (Sn) electrodes were directly deposited onto 3D-printed polymer substrates via CSAM and subsequently encapsulated through polymer over-printing, eliminating the need for surface pretreatment, thermal sintering, chemical metallization, or adhesive bonding. A systematic design of experiments with microstructural characterization established the process–structure–property relationships governing polymer metallization, identifying the optimal processing conditions for producing continuous conductive pathways with an electrical conductivity of 3.76 × 105 S·m–1. The versatility of the proposed approach was demonstrated through three representative fully embedded smart structures: (i) a strain sensor with a gauge factor of 2.766; (ii) a triboelectric nanogenerator (TENG) capable of generating a peak output voltage of ∼65 V and a peak power density of 3 μW cm–2; and (iii) a radio-frequency identification (RFID) circuit. These results provide a pathway toward smart polymer electronics (plastronics) for next-generation engineering systems.