Directly fixed and sealed ultra-thin membrane enables an autoclavable two-chamber bioreactor with selective permeability and optical access

An autoclavable microfluidic bioreactor (MBR) with an integrated gas-liquid contactor based on an ultra-thin permeable and transparent membrane enables a systematic analysis of intra-plant communication. The bioreactor units can be cascaded in a downstream manner, driven by a perfusion stream, to provide one-directional paths for allelochemical communication. Our article details a manufacturing pathway that achieves wrinkle-free membranes in these autoclaveable chips, by applying a drumhead-stretching design to the installed membrane. Traditional ultrasonic welding was used in the end as the bonding process, but absorber-free laser transmission welding was tested as well, and the results are reported in this article. In addition, we evaluated the membrane-stretching-behavior theoretically through simulations. The results of this analysis were then applied to the membrane installation. Through the new design and the application of the membrane stretching analysis, a reduction of the wrinkle amplitude in the installed membrane of on average over 80% was achieved, which in turn evened out the flow conditions in the MBRs. Therefore, in the future, the autoclavable bioreactors will be ready for cell culture experiments and the applied membrane integration provides an approach for other projects where ultra-thin permeable membranes need to be installed wrinkle-free.