AccScience Publishing / IJB / Online First / DOI: 10.36922/IJB025470480
RESEARCH ARTICLE
Early Access

Multi-material Vat photopolymerization: Computational optimization of slicing workflow for complex tissue geometries

Alejandro González-Santos1 Adrian García2 Nadina Usseglio2 Julián Flores1 Daniel Nieto2,3*
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1 Department of Electronics and Computing, University of Santiago de Compostela. Santiago de Compostela, CP 15782 Spain
2 Department of Electronics and Computing, University of Santiago de Compostela. Santiago de Compostela, CP 15782 Spain
3 Opportunius. Axencia Galega de Innovación. Santiago de Compostela, CP 15702, Spain
Received: 18 November 2025 | Accepted: 16 December 2025 | Published online: 19 December 2025
© 2025 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

Multi-material printing using digital light processing (DLP) has progressed from a niche laboratory method to a scalable technology capable of fabricating complex and functionally tissue constructs. However, current multi-material DLP workflows face significant limitations. Material changes typically require repeated washing and reloading steps, increasing print time, risking cross-contamination or layer misalignment, and ultimately constraining scaffold design complexity and biological relevance. To address these challenges, we present a computational pipeline that significantly improves the efficiency, precision, and usability of DLP for multimaterial bioprinting. Our system includes three key innovations: (1) a high-resolution segmentation and material-labeling method using computer graphics techniques for accurate material assignment in STL models; (2) a computer vision–based algorithm for real-time detection and correction of material interference or contamination; and (3) a GPU-accelerated layer sequencing method that supports rapid, precise material switching within single-layer projections. Experimental validation demonstrates improved print fidelity, reduced processing time, and higher material resolution. We further showcase the practical utility of our system by bioprinting a multimaterial tissue construct composed of a PEGDA-based scaffold integrated with a GelMA-based cell-laden microenvironment. This work represents a significant step toward enabling scalable, high-resolution, and biologically functional scaffold fabrication for advanced tissue engineering applications.

Keywords
Multimaterial DLP printer
3D Printing protocol
Slicing
Process Planning Algorithm
Funding
Alejandro González-Santos was supported by a predoctoral research grant from the Xunta de Galicia (Consellería de Cultura, Educación, Formación Profesional e Universidades). This grant was co-funded by the European Union (FSE+ Galicia 2021-2027). Daniel Nieto thanks the European Research Council Consolidator Grant (101125172 HOT-BIOPRINTING- HE-ERC-2023COG). Daniel Nieto is supported by the Oportunius Programme (Xunta de Galicia) since 2024.
Conflict of interest
The authors declare no conflict of interest.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing