Vascular network integration in in vitro models: design and validation of a microfluidic pump prototype.

A Peristaltic Pump is a Positive Displacement pump, named after peristalsis, which is the progressive constriction and relaxation of a tube. These pumps play a crucial role in supporting the development of more reliable in vitro models, by replicating physiological dynamic conditions and shear stresses. This master thesis, conducted in collaboration with the Company IVTech srl, focused on designing and developing a peristaltic pump head prototype, to replace the commercial head model currently in use in the IVTech Live Flow system. The pump head prototype was designed using a 3D modelling software, and each component was developed according to company specifications. The aim was to maintain the positive features of the commercial model, including a compact design and modularity, while refining some defects. The current head, though functional, has only three rollers, needs an extra part to connect to the pump, and leaves the crankshaft exposed when removed. The company aims to enhance these limitations for greater compatibility with the laboratory setting and enhanced performances. Key improvements included addition of rollers, generation of a more stable flow, and design of better coupling system for easier integration with laboratory workflows. Two pump head designs were presented, differing in their rotation system. The first design incorporated a gear reduction ratio between the shaft and four rollers, while the second featured a direct-drive system with six rollers. After optimising both designs, the components were 3D printed at the company's facility using Fused Deposition Modeling, while the rollers were produced via Stereolithography. Both designs were assembled and tested for function and flow, leading to the selection of the most promising design. The first design, although functional, had inherent limitations. Its operation relied on a gear reduction ratio using printed components, but the printing process did not ensure the precision needed for a reliable coupling. On the contrary, the second design had a simpler motion transmission and could more easily guarantee correct constant functioning. For these reasons, the second design was selected for further testing. A first in use validation test was conducted by seeded endothelial cell (EC) in the device and exposed to a constant medium flow. These cells are physiologically exposed to high shear stress from blood flow, which cannot be reproduced in static conditions. A static culture was compared with a dynamic culture in the IVTech LiveBox1 bioreactor for 48 hours, generating a flow of 200 µL/min with the newly designed pump head. Additionally, the effect of exposure to increasing flow rates on ECs was tested. The tests demonstrated excellent results, with the pump head prototype achieving flow rates between 150 and 1500 µL/min, addressing a range not covered by the existing IVTech pump head. In the biological assays, differences in cell morphology and orientation were observed between the samples. Dynamic ECs were aligned and elongated in the direction of flow, highlighting the positive response of ECs to flow conditions. In conclusion, the prototyping phase was successfully completed, resulting in a fully functional device. This modular pump head with six rollers ensured the generation of a more uniform flow, displayed user-friendly featured and integrated seamlessly with standard laboratory workflows. IVTech will continue the development of this pump head towards industrial production.