Automated and dynamic extrusion pressure adjustment based on real-time flow rate measurements for precise ink dispensing in 3D bioprinting

Wenger, Lukas; Strauß, Svenja; Hubbuch, Jürgen

doi:10.1016/j.bprint.2022.e00229

Cited by 7 publications

(3 citation statements)

References 47 publications

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“…This approach increases the comparability of results, as printing parameters are objectively set on the basis of rheological data and not determined according to user-dependent impressions. Further methods to control the flow rate as performed by Wenger et al [34] showed increasing reproducibility during extrusion-based bioprinting. The higher standard deviations shown by the cell-containing bioinks can be explained by air entrapment when the cells are mixed into the polymer solution between two syringes.…”

Section: Printing Accuracy Assessmentmentioning

confidence: 99%

Analytics in Extrusion-Based Bioprinting: Standardized Methods Improving Quantification and Comparability of the Performance of Bioinks

2023

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Three-dimensional bioprinting and especially extrusion-based printing as a most frequently employed method in this field is constantly evolving as a discipline in regenerative medicine and tissue engineering. However, the lack of relevant standardized analytics does not yet allow an easy comparison and transfer of knowledge between laboratories regarding newly developed bioinks and printing processes. This work revolves around the establishment of a standardized method, which enables the comparability of printed structures by controlling for the extrusion rate based on the specific flow behavior of each bioink. Furthermore, printing performance was evaluated by image-processing tools to verify the printing accuracy for lines, circles, and angles. In addition, and complementary to the accuracy metrics, a dead/live staining of embedded cells was performed to investigate the effect of the process on cell viability. Two bioinks, based on alginate and gelatin methacryloyl, which differed in 1% (w/v) alginate content, were tested for printing performance. The automated image processing tool reduced the analytical time while increasing reproducibility and objectivity during the identification of printed objects. During evaluation of the processing effect of the mixing of cell viability, NIH 3T3 fibroblasts were stained and analyzed after the mixing procedure and after the extrusion process using a flow cytometer, which evaluated a high number of cells. It could be observed that the small increase in alginate content made little difference in the printing accuracy but had a considerable strong effect on cell viability after both processing steps.

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Section: Printing Accuracy Assessmentmentioning

confidence: 99%

Analytics in Extrusion-Based Bioprinting: Standardized Methods Improving Quantification and Comparability of the Performance of Bioinks

2023

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“…The presented data in this comparison demonstrated the influence of the extrusion mechanism leading to non-reproducible printing processes, and showed the advantages of piston-operated extrusions systems used in the field of bioprinting. Alternatively, further methods to increase the reproducibility of pneumatic extrusion have been presented by Armstrong et al [38] and by Wenger et al [39]. Both studies involve the process monitoring and adaptation of the pneumatic pressure.…”

Section: Case Study 1: Pneumatic Vs Mechanical Extrusionmentioning

confidence: 99%

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

Grijalva Garces,

Strauß,

Gretzinger

et al. 2023

Biofabrication

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The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established.

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“…The advantage of real-time data processing is that it allows decisions to be made instantly and future trends to be forecast promptly. For fluid devices, real-time measurements are expected to contribute to optimal printing using the real-time measured flow rate of ink in 3D bioprinters [6] and aerodynamic control by measuring the flow around wings [7]. Time-and space-resolved flow visualization [8] would provide an intuitive approach for real-time image processing, although the acquisition and analysis of large-scale image data must be improved.…”

Section: Introductionmentioning

confidence: 99%

Analytic Approximation of High-Fidelity Solar Radiation Pressure

Yoshimura

Matsushita

Takahashi

et al. 2023

Journal of Guidance, Control, and Dynamics

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This paper describes the use of a high-speed streaming camera combined with in-house image processing for real-time particle tracking velocimetry (PTV) above 1 kHz. The proposed system is evaluated by measuring the diameter and velocity of multiple free-falling droplets in a simultaneous manner. Two existing particle tracking methods are examined: median flow (MF) and fourframe best estimate (4BE). Area-limiting processing is newly added to MF and 4BE to reduce the region of interest (ROI) in which particles are detected in the next image, resulting in area-limiting MF (AMF) and area-limiting 4BE (A4BE). Except for MF, the rest three methods of AMF, 4BE, and A4BE are capable of 1-kHz real-time PTV for 1246 pixel × 600 pixel images, with 4BE and A4BE achieving even at 10 kHz for 1246 pixel × 100 pixel images. The processing times for the tracking and image preparation are measured, and the bottleneck is found to be the image acquisition and preparation, rather than the tracking. AMF achieves faster processing times than MF in all conditions, showing the effectiveness of the limited ROI, while 4BE and A4BE exhibit comparable performance. The measurement error is confirmed to be approximately 1% for the droplet velocity and diameter, demonstrating the high accuracy of the first in-situ real-time PTV exceeding 1 kHz.

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Automated and dynamic extrusion pressure adjustment based on real-time flow rate measurements for precise ink dispensing in 3D bioprinting

Cited by 7 publications

References 47 publications

Analytics in Extrusion-Based Bioprinting: Standardized Methods Improving Quantification and Comparability of the Performance of Bioinks

Analytics in Extrusion-Based Bioprinting: Standardized Methods Improving Quantification and Comparability of the Performance of Bioinks

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

Analytic Approximation of High-Fidelity Solar Radiation Pressure

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