Figure 1.

Bioreactor design and fabrication. (A) Computational fluid dynamic software was used to identify an appropriate impeller configuration and fluid flow regimes for human induced pluripotent stem cell cultivation in silico. (B) The custom-made miniature continuously stirred tank reactors (CSTRs) were designed for operation in an incubator. The largest components are the baseplate (1), the glass support (2), the lid (3), and the motor coupling (4). These parts are enclosing the culture glass vessel (5) and were produced by in-house fused filament fabrication (3D printing). All reactors are equipped with optical oxygen sensor spots (6) and pH sensor spots (7) that are attached to the inside of the glass wall. The rotating shaft is stabilized by a stainless steel ball-bearing (8). Sterile conditions inside the vessel are ensured by a shaft seal (9) that is placed below the ball-bearing. A total of four baffles (10) promote homogenous fluid mixing. Luer-lock ports (11) provide head-space gas exchange with the surrounding atmosphere of the incubator through air filters and also allow fluid removal and fluid addition by riser pipes. (C) Computer-aided design sketches of bioreactor components at the beginning of the manufacturing process. Components are translated into mesh files that are subsequently sent to the 3D printing software that automatically outlines the print flow. Component labelling is identical to (B). In addition, caps for riser pipe ports (12, not shown in (B)) are added to the printing interface. (D) Components at final stage of printing after approximately 4 h.