Described embodiments include an apparatus (21) for removal of a thrombus from a body of a subject. The apparatus includes a first electrode (3), made of a first conductive metal having a first electronegativity, and a second electrode (26), made of a second conductive metal having a second electronegativity that is less than the first electronegativity. The apparatus further includes a voltage source (46), configured to apply a positive unipolar voltage between the first electrode and the second electrode while the first electrode is in contact with the thrombus, and while the second electrode is inside the body of the subject. Other embodiments are also described.
