# Structured Data Storage for Data-Driven Process Optimisation in Bioprinting
[PERSON] and [PERSON] [29] stressed in their report on histology analysis in the medical field that further meaningfulness can be reached by limiting the number of possible analysis outcomes by drop-down lists and categorisation. To access complex data sets, many commercial and non-commercial database system and software solutions are available [30]. Among projects for storage as open-access data repositories [31,32], national and international initiatives as well as non-governmental organisations establish systems to make information available long-term for further research and retrospective analysis. For example, the European Cloud Initiative [33,34] supports the development of secure cloud technologies. Collaboration and digitalisation in the field of materials science are encouraged by the Materials Genome Initiative [35]. The RCSB Protein Data Bank [36] shares biochemical information for science and education. The German National Research Data Infrastructure for Engineering Sciences (NFDI4 Ing) offers concepts to stimulate the findable, accessible, interoperable and re-usable (FAIR) management of research data [37,38]. As a part of NFDI4 Ing, KadiMat (Karlsruhe Data Infrastructure for Materials Science) [39] is an open source software for managing research data that is developed at the Karlsruhe Institute of Technology. The software is best described as a virtual research environment that combines and builds upon features of ELNs and repositories, enabling a comprehensive documentation of scientific workflows. While materials science is the current focus of development, KadiMat is mostly kept generic, not least due to the heterogeneity of materials science-related disciplines. For example, KadiMat has already been successfully used for structured data management in experimental tribology [40,41]. As a result, the usage and adaption to specific fields such as bioprinting is not only possible but highly encouraged. This generic approach and combination of functionalities sets KadiMat apart from other open source systems, which are either focused on specific disciplinesor workflows. Examples of discipline-specific systems are the NOMAD Repository [42], which focuses on materials science data of specific codes, or the Chemotion ELN [43], which targets experimental work in organic chemistry. To the best of the authors' knowledge, however, there are no tailor-made solutions for bioprinting. Generic systems such as eLabFTW [44] can in principle be used in bioprinting, but due to its focus on handwritten notes and unstructured data and metadata as a core part of its ELN functionality, it is less suitable for implementing standard operating procedures and machine-readable data transfer, as intended in this work. In an effort to analyse the robustness and the transferability of the bioprinting process, the project SOP_BioPrint, which is funded by the German Federal Ministry of Education and Research, establishes and validates an infrastructure for standardisation and collaboration in extrusion-based bioprinting. This includes the development of standardised protocols and the systematic documentation of SOPs, lab journal entries and results across different sites for automated analysis and the validation of their practicability. This manuscript thus presents a concept for a data management structure for round robin tests including all steps of a bioprinting process from raw material characterisation to the analysis of the printed objects. To address the fact that data-driven research can mean not only sharing, but also protecting, sensitive research data, a double-blind round robin test with 15 participating laboratories was designed within the research data infrastructure KadiMat [39] as a proof of concept for the developed infrastructure. Workflows, SOPs and construction data for bioprinting model geometries were pre-set in the system with the aim to increase the reproducibility between the locations. Bioprinting groups 3D printed a series of hydrogel structures and documented their experimental data in Kadi4 Mat.