Electrospinning technology has been widely used to fabricate polymer fibers with various hierarchical structures from 1-D to 2-D to 3-D, accomplished by changing electrospinning setups and processing factors. The fiber matrix can be made of any number of diverse polymer materials, with the fiber diameter ranging from nano- to micrometre and the fiber morphological readily tuneable. These electrospun fibers have been employed for drug delivery, tissue engineering, disease diagnostics and many other applications.