Impact of resin reuse on form accuracy in 3D printed microchannels and effects on hydrodynamic flow stability

This work investigates the impact of resin reuse on the form accuracy and hydrodynamic stability of microfluidic channels fabricated via Projection Micro-Stereolithography (P$\mu$SL). Three micro-optofluidic (MoF) devices were manufactured using fresh, once and twice reused photocurable resin batches. Resin reuse offers a sustainable approach that addresses recycling challenges associated with cured acrylate and methacrylate resins, making it an increasingly effective option for eco-friendly manufacturing. The devices were tested through an air–water bi-phase flow to assess hydrodynamic stability. A Phase I distribution-free quality control approach employing recursive sequential and permutation (RS/P) methods was conducted to evaluate channels’ width stability, while Fourier Transform Infrared Spectroscopy (FT-IR) was exploited to track chemical changes in reused resin batches. A Design of Experiment (DoE) study allowed hydrodynamic performance to be analyzed for the devices, revealing that increasing the flow rate to 0.3 $\mathrm{mL/min}$ enhanced stability across all devices, overcoming flow constriction effects caused by the photocurable resin reuse.