Novel solvent bonding method for thermoplastic microfluidic chips

This paper presents a novel solvent bonding method aimed at improving the strength of bonds formed between PMMA/PMMA, PMMA/PC, and PMMA/PET thermoplastic substrates. We applied spin-coating as an alternative to the dropping method for the distribution of ethanol solutions on thermoplastic substrates. Initial experiments demonstrate the efficacy of this method in preventing the evaporation of solvent, producing a uniform, bubble-free layer of solvent, and creating a strong bond between thermoplastic substrates. We then conducted experiments to characterize the influence of solvent uniformity on bonding strength. In all of the experiments, microchannels milled on the surface of PMMA substrates were sealed with PMMA, PC, or PET substrates. Leakage tests, cross-sectional investigation using SEM, and burst pressure tests were then used to quantify the performance of bonding in the experiments. The experiment results clearly showed that this novel solvent bonding method successfully formed a strong bond between PMMA/PMMA, PMMA/PC, and PMMA/PET thermoplastic substrates, and the bonding strength of at least nine bars was achieved.