This chapter discusses the fabrication techniques and materials used to create microfluidic devices suitable for organ-on-a-chip (OoC) applications. Section 2 highlights the relevant physical theories of fluid flow in the micrometer scale. Next, Section 3 discusses critical design considerations for OoC developers when developing microfluidic devices for OoC applications. Section 4 introduces existing techniques and materials employed to fabricate microfluidic devices. Lastly, Section 5 discusses the outlook of microfluidics in the context of OoC development.