## 1 Introduction
It consists of three layers: the hypodermis, dermis and epidermis (epithelium), of which the latter two are separated by a basement membrane (BM) [7]. Culturing a stratified epithelium, as found in the skin, requires an adhesive surface which is porous to nutrients but does not allow cell invasion to support the growth and differentiation of epithelial cells [8]. Fibroblast cells found in the lamina propria or dermis support the adhesion of epithelial cells and require a porous scaffold with interconnected pores which mimic the ECM structures found in native tissue. The hypodermis is a loose connective tissue with large pore, capable of supporting the growth of large adipocyte cells. For skin tissue, a biomimetic scaffold should exhibit three layers, i.e., two porous layers with different pore sizes to support fibroblasts and adipocytes, and a BM-like layer on top to provide a surface to which epithelial cells can attach and grow without infiltrating the other two layers. Tendon tissue is comprised of a single tissue layer populated with tenocytes, but has an oriented microstructure in the load axis to connect a muscle with a bone and transfer the forces induced from the muscle to the bone to create motion [9]. Therefore, the scaffold for tendon tissue should ideally have an oriented anisotropic, porous structure to allow tenocytes to penetrate, distribute and produce tendon tissue in a guided anisotropic structure. Multilayer scaffolds were fabricated to mimic the multilayer structure of native tissues using various methods [10; 11]. For example, silicon wafer moulds coated with a maltose-sacrificial layer were used to fabricate double-layer poly(glycerol sebacate) (PGS) porous scaffold with 50-250 \(\upmu\)m pore size for the purpose of cardiac tissue engineering [10]. It was found that the bilayer structure of the scaffolds provided a platform for cell delivery, promoted cell growth and had mechanical properties similar to the normal heart muscle. However, the disadvantage of the micromooulding fabrication technique is that it requires multiple steps to prepare the moulds, involves a sacrificial layer to allow the detachment of the cast polymer and can only produce thin scaffolds, approximately 150 \(\upmu\)m thick, which limits their scalability and application. In another study, casting, moulding and freeze drying techniques were used to develop a natural triple-layered vascular graft made out of collagen type I, fibrils and elastin fibres for vascular tissue engineering [11]. Three tubular moulds that had different sizes were used to build the scaffold layer by layer, and it was found that the scaffolds exhibited suitable morphologies and properties for vascular tissue engineering. In addition, anisotropic monolayer scaffolds were also manufactured for tissues that require anisotropy [12]. The advantage of having oriented pore architecture is that it can mimic the natural in vivo ECM of those tissues which require alignment--for example, tendon and skeletal muscle. Successful attempts to fabricate scaffolds with anisotropic pore architecture by using freeze drying and custom-made moulds that either produced temperature gradient due to difference in the thermal conductivity between the mould materials [13; 14; 15; 16], or submerged the solvent into a cold bath at a constant rate [17], were reported using various biomaterials, such as collagen, gelatin, poly(vinyl alcohol) and PLGA. The custom-made moulds were comprised of either a metal base and Perspex walls [13], polytetrafluoroethylene (PTFE) mould placed on a copper cold finger [14], metal base with polyethylene walls [15] or plastic tubes that had their walls further isolated with Styrofoam [16]. These moulds induced a temperature gradient during the freezing of the polymer solution, and after freeze drying, the resulting scaffolds exhibited anisotropic microstructures but, in some cases, the scaffold microstructures were characterised by a dense non-oriented layer at the bottom due to a higher cooling rate [13; 14].