An energy harvester device for an autonomous intracorporeal leadless capsule having an outside surface (42) on the body (40) of the capsule, that is deformable under the effect of pressure variations in the environment surrounding the capsule. A first capacitor electrode coupled to the deformable surface and a mechanical damping element (68) form a high-pass filter with respect to the pressure variations, and a second capacitor electrode (54) is mounted on a support (56) connected to the body. The deformable surface movement produces a correlative modification of the spacing between the two electrodes with a correlative variation of the capacity of said capacitor. The capacitor is preloaded when its capacity is maximum, it is unloaded by transferring its energy into a storage circuit when this capacity decreases under the effect of a reduction in the opposing surfaces and/or of an increase of the dielectric gap.
