An apparatus and method are provided for spatially-selective administration of actions by at least one device in the body using a transducer that is sensitive to a spatially-variant energy field imposed on the at least one device by a source external to a subjects body and at least one component in the at least one device, wherein interaction of the transducer with the imposed spatially-variant energy field causes or enables at least one component in the at least one device to affect nearby tissues in the body.
