## 1 Introduction  
Tissue engineering and regenerative medicine strategies focus on the creation of biological substitutes for clinical therapeutics and diagnostics, drug screening, and disease modelling through the application of multidisciplinary engineering and life sciences principles [1,2]. One widely used strategy relies on the use of three-dimensional (3D) substrates, referred to as scaffolds, to house cells throughout their porous micro-architecture and serve as a template for the generation of extracellular matrix (ECM). In addition to providing the appropriate physiological environments for cells to proliferate and secrete ECM, scaffolds must also possess mechanical and structural properties comparable to those of native tissues. Scaffolds have been fabricated using a variety of biomaterials ranging from natural materials such as collagen, chitosan, hyaluronic acid, alginate, and silk fibroin to synthetic polymers including polycaprolactone (PCL), polylactic acid, polyglycolic acid, and polyurethane [3, 4]. PCL, a biodegradable semi-crystalline linear aliphatic polyester that is already being used in medical devices approved or cleared by the Food and Drug Administration (FDA), has been one of the most commonly investigated scaffold biomaterials. A simple Google Scholar search using the keyword \"PCL scaffolds\" showed over 8775 results. PCL is miscible with a large range of other polymers and has a relatively slow biodegradation rate as well as a relatively low melting point. The latter property especially makes it suitable for several fabrication processes. Scaffold fabrication can be classified into traditional processes (e.g., solvent casting/particulate leaching, freeze-drying, phase inversion, electrospinning) and additive manufacturing (AM) processes (e.g., selective laser sintering (SLS) [5, 6], fused deposition modeling (FDM) [7, 8], 3D Bioplotting (3 DB) [9, 10, 11], stereolithography [12, 13]). In recent years, AM processes have become more prominent because they offer better control over scaffold macro- and micro-architecture, better reproducibility, and improved processing efficiency when compared to traditional processes. In general, AM processes offer greater flexibility to reproduce complex anatomical geometries, allowing for the creation of patient-specific scaffolds. 3 DB is one commonly used pneumatic extrusion-based AM process for scaffold fabrication. It allows for the processing of biomaterials in their molten or solution forms, thereby enabling the fabrication of acellular polymer scaffolds as well as cell-encapsulated hydrogel constructs [14, 15, 16]. Furthermore, multiple materials can be printed within the same build, thereby providing the ability to create hybrid constructs with a multi-material framework with or without encapsulated cells. Strands are the fundamental building blocks of bioplotted scaffolds; scaffolds are built layer-by-layer, and strands constitute each layer. The porous micro-architecture of a scaffold is governed by the strand dimensions, strand lay orientation, and inter-strand spacing. These parameters affect the scaffold mechanical properties as well as the distribution of cells and nutrient exchange once cells are cultured onto them. In 3 DB, since strands are created by extruding the melt through the nozzle of a moving dispensing head, process parameters such as the nozzle internal diameter, extrusion temperature, extrusion pressure, and nozzle speed affect the strand width. The strand width is sensitive to changes in these process parameters due to the non-Newtonian flow of the melt and the shear stresses as it is pressurized through the nozzle [17]. The mechanical properties are also affected by the process parameters due to melt deformation at the nozzle. There is strong evidence that the properties of polymers processed using extrusion-based AM processes differ significantly in comparison to their unprocessed or injection molded forms [18, 19].