A radioisotope-powered energy source comprising: a flexible center substrate coated with the radioisotope, wherein the substrate comprises upper and lower surfaces; and two substantially identical sequences of layers bonded to each other and to the upper and lower surfaces via electrically insulating mesh barriers, wherein each sequence comprises the following layers bonded together in a y-direction in the following order: a first low-density alpha particle impact layer, a first high-density beta particle impact layer, a second low-density alpha particle impact layer, a second radioisotope-coated substrate, a third low-density alpha particle impact layer, a second high-density beta particle impact layer, and a photovoltaic layer.