Abstract Body: Introduction: Contractility analysis is the gold standard for cardiac phenotyping, yet 3D models often require complex preparation and specialized equipment. We developed tunable gelatin microfibers (Genocel) to accelerate maturation and enable functional analysis using conventional microscopy. Hypothesis: Tunable gelatin meshes with their mechanical and biochemical properties accelerate iPSC-cardiomyocyte (iPSC-CM) maturation by providing structural alignment and enhancing diastolic relaxation. Methods: iPSC-CMs (45,000 or 10,000 cells per sample) were cultured for 14 days on gelatin microfiber meshes (30 μm fiber diameter; 5 mm disk diameter) or porous organoid-forming microfiber scaffolds. Contractility was monitored via a conventional inverted microscope using finite-element motion tracking displacement algorithms. Metabolic profiling by Seahorse assay is ongoing. Results: iPSC-CMs on Genocel scaffolds exhibited adult-like rod-shaped morphology with sarcomere lengths reaching 2.2 μm by Day 15, approaching values reported for adult cardiomyocytes. The tissues displayed rapid diastolic relaxation and significant positive inotropic responses to Isoproterenol (+36.4%), Milrinone (+24.7%), and Rolipram (+47.2%). Ongoing Seahorse analyses are evaluating whether the porous microfiber architecture helps maintain metabolic homeostasis by reducing diffusion limitations in 3D culture. Confocal imaging further verified successful adenoviral GFP expression throughout the depth of the 3D mesh. Conclusions: Genocel meshes provide a scalable platform (48-, 96-, and 384-well formats) for iPSC-CM maturation, enabling high-fidelity 3D cardiac phenotyping, drug testing, and mechanistic studies of disease- and mutation-specific cardiomyocyte phenotypes using conventional laboratory equipment.