If I understand right, the Harpejji uses individual per-string pickups and uses an electronic muting system. Touching a string to any of the frets completes a

If I understand right, the Harpejji uses individual per-string pickups and uses an electronic muting system. Touching a string to any of the frets completes a circuit that causes the onboard electronics to unmute that particular string. That's pretty unique. The Chapman Stick just uses a mechanical damper where the nut is so the open strings don't ring out, and fairly standard magnetic pickups.