sp in ning ▁ ▁A ▁co ax ial ▁setup ▁uses ▁a ▁dual - sol ution ▁feed ▁system ▁which ▁allows ▁for ▁the ▁injection ▁of ▁one ▁solution ▁into ▁another ▁at ▁the ▁tip ▁of ▁the ▁sp inner et . ▁The ▁she ath ▁fluid ▁is ▁believed ▁to ▁act ▁as ▁a ▁car rier ▁which ▁draw s ▁in ▁the ▁inner ▁fluid ▁at ▁the ▁Taylor ▁C one ▁of ▁the ▁electro sp in ning ▁jet . ▁If ▁the ▁solutions ▁are ▁imm is cible ▁then ▁a ▁core ▁shell ▁structure ▁is ▁usually ▁observed . ▁Mis cible ▁solutions ▁however ▁can ▁result ▁in ▁por os ity ▁or ▁a ▁fi ber ▁with ▁distinct ▁phases ▁due ▁to ▁phase ▁separation ▁during ▁solid ification ▁of ▁the ▁fi ber . ▁For ▁more ▁advanced ▁set ups , ▁a ▁tri ax ial ▁or ▁qu ada x ial ▁( t etra - ax ial ) ▁sp inner et ▁can ▁be ▁used ▁with ▁multiple ▁solutions . ▁ ▁Em ulsion ▁electro sp in ning ▁Em uls ions ▁can ▁be ▁used ▁to ▁create ▁core ▁shell ▁or ▁composite ▁fib ers ▁without ▁modification ▁of ▁the ▁sp inner et . ▁However , ▁these ▁fib ers ▁are ▁usually ▁more ▁difficult ▁to ▁produce ▁as ▁compared ▁to ▁co ax ial ▁spin ning ▁due ▁to ▁the ▁greater ▁number ▁of ▁variables ▁which ▁must ▁be ▁account ed ▁for ▁in ▁creating ▁the ▁em ulsion . ▁A ▁water ▁phase ▁and ▁an ▁imm is cible ▁sol vent ▁phase ▁are ▁mixed ▁in ▁the ▁presence ▁of ▁an ▁em uls ifying ▁agent ▁to ▁form ▁the ▁em ulsion . ▁Any ▁agent ▁which ▁stabil izes ▁the ▁interface ▁between ▁the ▁imm is cible ▁phases