This thesis presents a novel solvent bonding method aimed at improving the strength of bonds formed between PMMA/PMMA, PMMA/PC, and PMMA/PET thermoplastic substrates. A spin-coating procedure was applied 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 evaporation of solvent and producing a uniform, bubble-free layer of solvent between thermoplastic substrates. Two groups of experiments in order to characterize the influence of solvent uniformity and interfacial roughness on bonding strength were conducted. 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 imaging using SEM, and burst pressure tests were then used to quantify the performance of bonding in the experiments. In one set of experiments, at least nine bars of bonding strength were achieved. Further investigations also demonstrated that higher interfacial roughness increases the failure rate of bonds, shortens the life of bonds, and reduces overall bonding strength.

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