(415d) Low-Cost Automated Flat-Sheet Membrane Casting: An Open-Source, Advanced Manufacturing Approach

Automation is playing an increasingly important role in the rapid development of novel materials, as it improves the reliability and reproducibility of fabrication methods while reducing the overall time required for product development. However, implementing automated systems in the research and development of membrane materials is challenging, especially at the lab scale, where significant upfront expenses can impede the integration of automated equipment into laboratory infrastructure. This cost limitation often necessitates the use of unreliable techniques such as hand-casting membranes using a doctor blade, which limits the control over key membrane characteristics such as morphology, permeability, and selectivity. The ubiquity of consumer-grade robotics hardware such as Arduino based RepRap platforms provide an easily accessible, reliable, and customizable avenue for controlling critical membrane fabrication parameters such as shear rate and temperature. Herein, we describe the modification of a consumer-grade RepRap 3D printer (Wanhao Duplicator i3) for flat sheet membrane casting. We found that the membrane thickness standard error decreased by 25% when the standard mechanical end-stop switch (± 18.4 µm) was replaced with a high-precision magnetic Hall-effect sensor (BL-Touch, ± 13.8 µm). We further demonstrated the systems utility by preparing poly ether-ether ketone (PEEK) membranes at different shear rates (62.5 s^-1_, 125 s^-1, 250 s^-1), and casting temperatures (20°C, 30°C, 40°C). Finally, we discuss the impact of shear rate and temperature on pure water permeability, membrane morphology, and bubble point measurements, emphasizing the importance of automation control in the fabrication process for achieving reliable and reproducible membrane performance.