@article{SchlegelEngelsStoychevaetal.2021, author = {Schlegel, Volker and Engels, Andreas and Stoycheva, Vesela and Bifaretti, Stefano and Foitzik, Andreas}, title = {From Biomaterial to Organoid - Bioprinting for Practice}, series = {Materials Science Forum}, volume = {1016}, journal = {Materials Science Forum}, publisher = {Trans Tech Publications}, issn = {0255-5476}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-18802}, pages = {1285 -- 1290}, year = {2021}, abstract = {The current state of technology for 3D printing with biomaterials is based on the extrusion of viscous materials. Mostly, extrusion heads utilize pneumatic pressure systems or stepper motors to force the substrate onto a surface. These methods are well developed for high viscouse materials. However, processing low viscous liquids may cause leakages in the system. This could be solved by applying continuous extrusion. Additionally, in order to process gelable substrates, such as gelatine and agar, tempered print heads in combination with a multi stage tempering system are required to prevent the system from clogging. The ongoing work presented in this paper focuses on the development of an extrusion system, which should be able to process multiple viscosities of gelatine sequentially. In order to achieve this, several measurements to examine the properties, as well as the material parameters of different biomaterials are performed. In this process gel point, force resistance and elasticity are the factors of particularly interest. Due to their ability to gel and their availability, the most relevant biomaterials are gelatine and agar. Using this data, an extrusion system involving a peristaltic pump, a heated tube and a nozzle, has been developed. The next step envisaged is to calibrate the extruder based on the obtained data and finally to validate the printing process by printing simple geometric structures. Assuming that a positive evaluation is obtained, the printing system will be tested for printing first organic test structures from patient data using the examined biomaterials.}, language = {en} } @article{SchlegelEngelsBifarettietal.2018, author = {Schlegel, Volker and Engels, Andreas and Bifaretti, Stefano and Foitzik, Andreas}, title = {Validation of Material Parameters of Collagen Compositions for the Application as a Bioink}, series = {Materials Science Forum}, volume = {941}, journal = {Materials Science Forum}, publisher = {Trans Tech Publications}, issn = {0255-5476}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-18764}, pages = {2437 -- 2441}, year = {2018}, abstract = {The novel approach of an individualized medicine affects nowadays various areas of therapeutic treatment. Primarily, these include the application of pharmaceuticals, private point-of-care solutions, surgical procedures as well as steps of rehabilitation. However, beside these existing strategies the development of patient specific models for the training of clinical personal is currently insufficient. Such models are essential to prepare a personalized approach of medical care. One possible solution to address this problem could be the adaption of the established 3d printing technology for the processing of suitable biopolymers. The presented work is focused on the development of a printing system utilizing collagen. Therefore, it is intended to design multiple extrusion heads in accordance with the material parameters. In order to achieve the aspired physiological properties of the final model, a first set of experiments will be performed with several compositions of collagen to validate the fundamental mechanical characteristics. Hereby, the elasticity, thermal stability, force resistance as well as the haptic behaviour are of most interest. Afterwards, these obtained experimental results should be used to simulate the extrusion process and to validate the extruder concepts. In case of a positive evaluation these concepts are realized by using rapid prototyping technologies. Finally, this novel 3d printer will be used to print first organic test structures with collagen.}, language = {en} }