An implantable fluid delivery system may include a fluid reservoir configured to hold a supply of fluid, dispense that fluid under the control of an actuator, and be implanted within the body of a living host. The actuator may include a bellows configured to expand in a direction when inflated. The bellows may have folds with surfaces which run substantially perpendicular to the direction of expansion in a collapsed state and which define a stacked set of convolutions. Each convolution may have a collapsed height of no more than 1 mm and a width perpendicular to the direction of expansion of no more than 8 mm. Electrodes may be configured to come in electrical contact with an electrolyte within the bellows and to cause electricity to run through the electrolyte, thereby causing the electrolyte to break down into a gas and, in turn, to cause the bellows to expand.
