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Three-dimensional (3D) printing has emerged as a transformative technology for fabricating complex microfluidic devices, enabling features that were previously unattainable with traditional layer-by-layer soft lithography. One key challenge in advancing 3D-printed microfluidics is the integration of functional microvalves across multiple spatial orientations. This study explores the design, simulation, and experimental realization of novel microvalve configurations to overcome the limitations of conventional, single-plane valves. We hypothesize that non-traditional valve orientations, such as those with vertically printed membranes or perpendicular control channels, present unique fabrication and operational challenges, including membrane delamination and stress-induced failure. To address these issues, we developed optimized geometries and fabrication techniques, supported by computational fluid dynamics (CFD) simulations to predict and mitigate stress concentrations. Our results demonstrate successful implementation of previously unreported valve configurations, validated through pressure testing and flow control experiments. These advancements expand the versatility of 3D-printed microfluidic systems, paving the way for more robust and adaptable devices in biomedical, chemical, and environmental applications. 

Recently, there has been an increasing effort in developing new fabrication methods for rapid prototyping of microfluidic chips using laser cutting and 3D printing. However, although these approaches can readily generate rigid parts of the devices, it is not trivial to integrate flexible components (e.g. on-chip valve and/or pump membranes) within the same build. This has led to the recent adoption of thermoplastic polyurethane (TPU) membranes sandwiched between the rigid layers to introduce the necessary flexibility to the chips. Despite its utility, TPU is not without its challenges—it is relatively expensive and surprisingly difficult to source. To overcome these difficulties, our study introduces the use of common food wrapping film as a cost-effective and readily available alternative to TPU, demonstrating its compatibility in fabricating essential microfluidic components such as on-chip valves and peristaltic pumps. Our findings show that this alternative maintains the performance standards required for sophisticated microfluidic applications while significantly alleviating logistical and financial constraints. The results show high cyclability of the membrane, up to 850,000 in continuous testing conditions, at 1 Hz, while also can block the fluid flow at as low as 250 kPa. Regarding the micropumps, it was shown that adequate flow rate of around 4 μL/min can be achieved.