In one embodiment, a method includes discharging a first capacitor and discharging a set of capacitances present on a first set of lines of a touch sensor. The device further includes a second electrical or auxiliary circuit adapted to generate an electrical excitation signal with an excitation frequency derived from the clock frequency signals. The expandable container is coupled to a superior endplate member having a bone-contacting surface and an engagement surface effective to mate with a superior surface of the expandable container, and an inferior endplate member having a bone-contacting surface and an engagement surface effective to mate with an inferior surface of the expandable container.