P. Schneider, V. Sukhotskiy, L. Christie, T. Siskar, I.H. Karampelas, E.P. Furlani, K.W. Oh
University at Buffalo's Sensors & MicroActuators Learning Lab (SMALL),
Keywords: 3D printing, fused deposition modelling, wax microfluidics, finite volume method, thermofluidic modelling
Summary:Fused deposition modelling (FDM) has been extensively applied in the fields of rapid prototyping and 3D printing, but typically this technique has mostly been used for the fabrication of low melting point plastics. This paper presents an innovative application of the FDM technique in wax printing of microfluidic structures. Preliminary experimental fabrication and analysis of wax lines, as well as thermos-fluidic computational fluid dynamic (CFD) modeling of the printing process are presented. The CFD model solves the Navier-Stokes and the heat transfer equations in 3D with appropriate boundary conditions. The CFD modeling provides fundamental understanding to enable rational tuning of critical process parameters toward optimization of the printing process. This wax-based printing technique as described by , uses a printing style similar to that of FDM 3D printing in which a wax extruder tip, filled with molten beeswax is translated across a printing substrate using precise computer-based motion control to create wax-based fluidic circuit components at the microscale. Some of the advantages of this technique as compared to traditional microfluidic fabrication  include low cost, rapid prototyping, a broad range of printable shapes and a large selection of substrate materials ranging from glass, plastics, and metals. Adjustable system parameters include the following: extruder tip velocity, substrate temperature, angle of the extruder tip with respect to the substrate and substrate material. This process allows for a highly flexible system with greater feature sizes, which opens up new application areas. As the development of this technology progresses, system capabilities are being discovered and verified through modelling. In this presentation, we discuss the characterization of this wax based printing system in terms of resolution, uniformity, and functionality.