# Structured Data Storage for Data-Driven Process Optimisation in Bioprinting
## 3 Results
### Data Management in Kadi4 Mat
\begin{table}
\begin{tabular}{c c c} \hline
**Template** & **Type of Data** & **Allocated Information, Datasets and/or Files** \\ \hline \hline \multirow{8}{*}{Sandardised bioink preparation} & \multirow{8}{*}{Fixed metadata} & \multicolumn{2}{c}{Changlelog} \\ \cline{3-4}  & & Description for user: Aim of template and instructions on how to apply \\  & & & (includes embedded images) \\ \cline{3-4}  & & Link to: corresponding SOPs \\ \cline{3-4}  & & Experiment identification number \\ \cline{3-4}  & & Name and batch identifier of bioink \\ \cline{3-4}  & & User identification (anonymised) \\ \cline{3-4}  & & Timestamps of preparation and storage duration \\ \cline{3-4}  & & Weighed portions of bioink components \\ \cline{3-4}  & & Checkpoints: Bioink preparation executed as specified in SOP? \\ \cline{3-4}  & & Deviations/comments (free text option for user) \\ \cline{3-4}  & & & \\ \hline \multirow{8}{*}{Linked records (to generated record)} & \multicolumn{2}{c}{Image on ready-to-use bioink cartridge before bioprinting for air} \\  & & bubble assessment \\ \cline{3-4}  & & Linked records (to generated record) & Raw material analysis \\ \cline{3-4}  & & Individual bioprinting process \\ \hline \multirow{8}{*}{Individual bioprinting process (within pre-defined window of operation)} & \multirow{8}{*}{Generic metadata} & \multicolumn{2}{c}{Raw material analysis} \\  & & Individual bioprinting process \\ \cline{3-4}  & & Fixed metadata & Analogous to template “Standardised bioink preparation” \\ \cline{3-4}  & & Experiment identification \\ \cline{3-4}  & & User identification (anonymised) \\ \cline{3-4}  & & Timestamp of start and end \\ \cline{3-4}  & & Generic metadata & Temperature (ambient conditions, 3D printer cabinet, heating mantle, nozzle leave  
For the analysis of the data, filtering and grouping options within Kadi4 Mat facilitate structured data handling and processing. Whereas automated filtering is useful for machine-assisted analysis, various visualisation options are provided for manual review of the metadata, data and their relationships. One such example is presented in Figure 3 (additional visualisation in Video S1 and Figure S1 in the Supporting Information), which shows a graphical representation of all incoming and outgoing links of a given record within the ELN. These interactive graphs can be generated automatically via the GUI of Kadi4 Mat and were used to check on the progress of the documentation during the experimental phase. As the visualisation is based on links between the records, the user can display not only the hierarchical experimental structure but also the connected SOPs. To support the digital workflow in the laboratory such as the execution of process steps according to the SOP, a browser-based preview of corresponding file formats, such as Excel or PDF files, is possible. In order to view the result data, additional previews for STL and TIFF files were implemented. Some examples are shown in Figures S2-S4 in the Supporting Information. Figure 2: Screenshot of a record template in Kadi4 Mat for the documentation of bioink preparation where personal data has been removed. The upper half of the template shows its title and instructions, while the actual template data can be seen in the lower half. The latter contains both fixed metadata types, such as the description and type of a record, as well as generic metadata entries, including their keys, types and additional validation instructions. The round robin test was designed with independent analysis of the results, meaning the bioprinting labs and the analytical units were anonymised, resulting in a double-blind study. To manage access to the data within Kadi4 Mat, the built-in permission management was used, which enables the assignment of roles to individual users or groups of users,  
Figure 3: Visualisation of record links generated via Kadi4 Mat, showing all outgoing and incoming links of the dataset record represented by the node in the centre (highlighted edges of node) up to a certain link depth.