Multimodal bioprinting of pigmented skin with algorithm-tuned control.

This study addresses critical technical challenges in fabricating functional pigmented skin models via 3D bioprinting through the synergistic integration of droplet-based deposition and precision motion control. A hybrid bioprinting strategy was developed to create multilayer biomimetic architectures: the dermal layer was fabricated through extrusion of gelatin methacryloyl-polyacrylamide (GelMA-PAM) composites, while the epidermal layer incorporated precisely patterned melanocyte-laden GelMA-PAM arrays deposited via microvalve technology, subsequently solidified and populated with keratinocytes. To enhance printing reliability, a fractional-order proportional-integral control system optimized through particle swarm optimization (PSO-FOPI) was implemented, significantly improving motor speed regulation and positioning accuracy. Furthermore, a novel perfusion culture platform featuring polycaprolactone (PCL)-printed hollow grid scaffolds connected to a peristaltic pump system was developed. This innovation enhanced nutrient transport efficiency while reducing culture medium consumption to 10 % of conventional requirements. Histological characterization demonstrated uniform pigment distribution in the engineered skin model, with functional assays confirming excellent biological performance. This study establishes a multimodal biomanufacturing strategy that provides a robust technical framework for constructing artificial organs with complex architectures and functionalities.