Three-dimensional printing, or additive manufacturing, has emerged as a transformative technology capable of producing complex, customizable structures directly from computer-aided design models. Its integration with functional polymeric materials is opening new frontiers in applications spanning electronics, robotics, aerospace, sensors, and medical devices. Between 2010 and 2020, publications on 3D printed functional polymers rose from just five to 193 annually, reflecting intense interest from both academia and industry.
Despite this momentum, the field faces persistent challenges. Printable polymers must meet stringent criteria—mechanical strength, low shrinkage, suitable melting temperature, and environmental safety—while being compatible with specific printing processes. The limited diversity of such materials and difficulties in scaling production hinder broader adoption. Furthermore, layer-by-layer fabrication can introduce interfacial defects that degrade performance and lifespan.
Fused deposition modeling (FDM) remains one of the most widely used techniques due to its low cost and efficiency. Innovations such as polyvinyl alcohol-based EMI shielding composites and polyethylene-based thermal conductive filaments, prepared via solid-state shear milling and melt blending, have expanded material options. Conical screw extrusion systems now allow direct use of polymer pellets, reducing reliance on costly filaments and enabling improved printing of elastomers.
Direct ink writing (DIW) offers versatility in material selection and high active material content, finding use in stretchable electronics and soft robotics. Control over ink rheology—particularly shear-thinning behavior—is critical to prevent nozzle clogging and achieve fine resolution. Researchers have demonstrated that exploiting viscoelastic ink deformation can produce patterns finer than the nozzle diameter.
Selective laser sintering (SLS) excels at producing dense, complex structures from powders. Functional composites such as PA11-based piezoelectric powders and PA12-based conductive powders have been developed using hybridization and ultrasonic irradiation. Novel spheroidization equipment enables large-scale production of spherical powders with high fluidity and bulk density.
Stereolithography (SLA) and continuous liquid interface production (CLIP) deliver high precision, with layer thicknesses around 25 μm. Advances such as mobile liquid interfaces suppress adhesion-related defects and boost vertical printing speeds. Photocurable inks, both oil- and water-soluble, have been introduced to broaden functional material compatibility.
Functional devices produced via these methods are diverse. In electronic conductive applications, incorporating fillers like carbon nanotubes or graphene into polymer matrices yields conductive filaments and powders for FDM and SLS. Strategies such as filler enrichment on filament surfaces and hybrid filler systems have significantly improved conductivity, enabling applications in sensors for tactile, pulse, and pressure monitoring.
Thermal management devices benefit from aligned filler networks formed during FDM, enhancing in-plane thermal conductivity. Pretreatment methods, such as exfoliating graphene nanoplatelets and constructing continuous conductive pathways, have achieved conductivities exceeding 3 W/m·K, suitable for high-power electronics.
Electromagnetic interference (EMI) shielding devices leverage 3D printing’s ability to create tailored architectures with enhanced scattering and absorption. Lattice structures, core-shell composites, and micropatterned grids have achieved shielding efficiencies well above civil standards, though porous designs can compromise mechanical strength.
Electrochemical energy storage devices, including batteries and supercapacitors, exploit 3D printing’s capacity for customized, high-loading architectures. DIW has enabled fully printed batteries without traditional assembly steps, and interface-engineered conductive scaffolds have delivered areal capacities over 6 mAh/cm². Printed supercapacitors with reinforced structures demonstrate high capacitance, rapid charging, and mechanical flexibility.
Energy harvesting devices encompass piezoelectric, thermoelectric, and photoelectric systems. 3D printing allows complex geometries—cantilever beams, lattice structures—that enhance mechanical-to-electrical conversion in piezoelectric harvesters. Thermoelectric devices benefit from conformal shapes matching nonplanar heat sources, with porous structures reducing thermal conductivity and improving efficiency. In optoelectronics, DIW enables gentle processing of conjugated polymers, preserving photoelectric properties in integrated devices like quantum dot LEDs.
Future progress will depend on expanding the palette of functional printable materials, developing economically viable large-scale production methods, and overcoming interlayer bonding issues. Multiprocessing systems capable of integrating dissimilar materials in a single cycle could yield multifunctional devices without postassembly. Enhanced mechanical compliance and deeper understanding of structure–performance relationships will be crucial for practical, durable applications.
As printing speeds, resolution, and material capabilities advance, functional polymeric 3D printing stands poised to revolutionize manufacturing across electrical, thermal, electromagnetic, and optical domains, offering unprecedented design freedom and application potential.