Abstract: A parylene microcapillary is manufactured by drawing a polyethylene carbonate (PEC) fiber from a 0° C. solution of 12-25% PEC in chloroform to create a PEC fiber that has a constant diameter over several centimeters. Parylene is deposited in a chamber over the PEC fiber, and then the coated PEC fiber is heated above 180° C. This heating melts and decomposes the PEC fiber such that it self-expels from the coating, leaving a microcapillary. The self-expulsion allows for meters-long lengths of microcapillaries. Alternatively, a serpentine fiber channel of PEC is created by deposition, photolithography, and etching within a sandwich of parylene. It is heated above 180° C. to expel the PEC leaving a hollow channel within a mass of parylene. The resulting microcapillaries may have residues of cyclic ethylene carbonate remaining from the decomposed PEC.