An experimental approach to manufacturability assessment of microfluidic devices produced by stereolithography

Lab-on-a-Chips integrate a variety of laboratory functions and embed microchannels for small fluid volume handling. These devices are used in medicine, chemistry, and biotechnology applications but a large diffusion is limited due to the manufacturing cost of traditional processes. Additive Manufacturing offers affordable alternatives for the production of microfluidic devices, because the fabrication of embedded micrometric channels is enabled. Stereolithography gained particular attention due to the low cost of both available machines and suitable polymeric materials to be processed. The main restriction to the adoption of this technique comes from the obtainable dimensional accuracy that depends not only on design, but also on process set-up. Firstly, the paper analyses theoretically the physics of stereolithographic processes and focuses on main phenomena related to microchannel manufacturing. Then, specific experimental activities are designed to investigate the combined effect of design and process parameters on the achievable dimensional accuracy of embedded microchannels manufactured through a commercial desktop stereolithography apparatus. In particular, the combined effect of channel nominal dimensions, build orientations and the layer thickness on the obtainable accuracy is examined by referring to a benchmark geometry. The collated experimental data showed that a number of combinations are successful. Besides, the experimental activity revealed that appropriate combinations of design, build orientation and manufacturing parameters can overcome the dimensional limitations reported in previous studies. Both binary logistic regression models to predict the manufacturability of microchannels and linear regression models to estimate the achievable accuracy for those geometries that can be produced successfully are developed.