Modeling 3D Printed Check Valves for Microfluidic Systems

Passive, one-way valves, also known as check valves, while common at the macro scale, are an essential microfluidic feature that facilitates flow rectification. These structures are commonly used in micropump configurations to control flow. Check valves have numerous applications within microfluidics with the large majority being fabricated by replica molding. There has been a shift towards 3D printing microfluidics to reduce the time and cost associated with developing prototypes. Only a handful of studies have developed microvalves using stereolithography (SLA). However, fused deposition modeling (FDM) printers are more widely available and cost effective compared to SLA. This study focused on analyzing the range of valve thicknesses necessary to promote forward flow using commonly available FDM filaments. An arbitrary Lagrangian-Eulerian model, a form of fluid-structure interaction (FSI), was set-up in COMSOL Multiphysics 4.2a. Five 3D printer filament materials were compared in simulations of valve deformation over a 0.75 second transient period using the material properties of PDMS as a baseline. The maximum valve deflection for ABS, nylon, PETG, PLA, and TPU was 3.34, 3.08, 3.37, 3.00, and 6.45 μm, respectively. The simulation resulted in a maximum valve deformation of 6.65 μm for PDMS. As expected, materials with a Young's modulus close to PDMS allows valve structures to actuate with adequate forward flow.