Wireless neurostimulators

A subcutaneous implant, including: (a) a circuitry unit having a first end, a second end, a conducting lateral side, and an opposing lateral side; (b) a first electrode, disposed on an outer surface of the circuitry unit and laterally circumscribing the circuitry unit at the first end; (c) a second electrode, disposed on the outer surface of the circuitry unit and laterally circumscribing the circuitry unit at the second end; (d) circuitry, disposed within the circuitry unit, and configured to be wirelessly powered to drive an electrical current between the electrodes; and (e) an insulating member, disposed on the opposing lateral side such that, on the opposing lateral side, each electrode is sandwiched between the insulating member and the circuitry unit, and the insulating member inhibits electrical conduction from the electrodes into the tissue. Other embodiments are also described.