Abstract: Methods and devices are disclosed for the controlled formation of structures, including tubular structures, using microfluidic devices. In one embodiment, a microfluidic device includes three or more microfluidic arrays that are provided in a stacking configuration, with an inner streaming layer and an outer streaming layer for flowing a streaming fluid, and at least one intermediate matrix layer for flowing a matrix fluid. Fluid flow in each layer is directed from a peripheral region towards, and distributed around, a common central outlet. Guided by the streaming fluid, a sheath of matrix solution is formed, which may be solidified to form a tubular material. Some embodiments allow for the controlled and continuous extrusion of tubular structures with tailored heterogeneities and/or predictable mechanical and chemical properties. Devices and methods are also provided for the on- and off-chip fixation and optional perfusion of tubular structures.