Iontophoresis
A transdermal delivery system in which a substance bearing a charge is propelled through the skin by a low electrical current.
This method can be used to drive a drug across the skin barrier, as is done with pilocarpine to stimulate sweating in the sweat chloride test for cystic fibrosis.
Iontophoresis can also be used in the reverse direction to draw a molecule such as glucose through the skin