When optimizing the bioink formulation, understanding the effects of fluid flow during the droplet incubation and airdrying processes of μCP pointed to the use of an additive or agent within the bioink to prevent failure modes. In sessile droplets, after the application of the bioink to the stamp, the biomolecules tend to flow towards the periphery of the droplet due to surface tension gradients along the liquid-air interface, known as the Marangoni effect (Figure ). This occurred whether higher or equal EDC/NHS to BSA-FITC were used. To assess how the Marangoni effect affects bioprinting and BSA-FITC immobilization after μCP, profilometry was conducted and surface topography was mapped on the printed substrate. As shown in the profilometry images (Figure and Figure ) and roughness profiles (Figure ), the immobilized biomolecules accumulate along the edges, resulting in higher roughness values, with less biomolecules present in the center of the feature, known as a "coffee ring effect." By increasing viscosity, the Marangoni effect can be suppressed and the coffee ring effects minimized, for more uniform immobilization of biomolecules. Two additives of (3-Glycidyloxypropyl)trimethoxysilane (GLYMO) and glycerol were assessed for the optimization of the bioink formulation. GLYMO is an epoxy-based silane coupling reagent that can facilitate conjugation and chemical attachment of biomolecules to the surface through epoxy ring opening mechanism. However, in our experiment, epoxy showed reduced SNR of μCP microarrays, as it also prolonged the airdrying step (Figure ) The increased wetness from the epoxy-based additive may stem from overly increasing the viscosity, resulting in a gel-like droplet, making the droplet removal step inconsistent. The extreme wetness prevented rapid airdrying of the droplet, making the μCP unsuitable for industry fabrication, which requires high speed, seamless and efficient production. This suggested that an alternative additive was needed to increase the viscosity of the bioink and reduce Maragoni effect, without increasing wetness or inducing highly gel-like bioink consistency. Application of glycerol resulted in an increase of the SNR values. This could be attributed to the effect of glycerol in reducing Marangoni effects and air-drying times compared to GLYMO. Thus, glycerol showed more applicability in the μCP protocol for industrial fabrication as a more efficient and timelier bioink additive. We further investigated the optimum concentration of glycerol in the bioink (Figure ). While the SNR values showed no significant difference amongst various glycerol concentrations, the 0.25% glycerol bioink, compared to the 0.1% glycerol bioink, showed lower %CV overall within the same print (intra-assay %CV), and between multiple prints (inter-assay %CV), indicating better repeatability and reproducibility. Specifically, the intra-assay %CVs were 8.81% and 13.58% for the 0.1% glycerol bioink, while for 0.25% glycerol bioinks, the intra-assay %CVs were 8.05% and 5.65%, after 3-min dry time. Meanwhile, the inter-assay %CVs were 11.19% and 6.85%, for the 0.1% and 0.25% glycerol bioinks, respectively (Table ). These differences in %CV are visible in the fluorescent images of all glycerol bioinks, as the 0.25% glycerol bioink had consistent square shapes and low background noise (Figure and Figure ).