Patent Number: 
Section: claims

1. A betavoltaic power source that generates electrical energy for use by a mobile device, comprising:a plurality of isotope layers, each isotope layer including an isotope that emits radiation, and wherein each isotope in the isotope layers is selected from the group of isotopes comprising: (3)H, (194) Os, (228)Ra, (155)Eu, (147)Pm, (171)Tm, (172)Hf, (179)Ta, (109)Cde, (106)Ru, (68)Ge, (195)Au, (45)Ca, (139)Ce and (181)W; anda plurality of energy conversion layers interposed between some or all the isotope layers and that receive and convert energy from the radiation into electrical energy sufficient to power the mobile device, wherein the plurality of isotope layers and the plurality of energy conversion layers define a stack having a perimeter;a plurality of continuous cooling conduits defined by thermally conducting rods that reside inboard of the perimeter and that pass through the stack so that heat generated within the stack is drawn out of the stack through ends of the rods; andwherein the amount of electrical energy generated is at least 10 mW. 2. The betavoltaic power source according to claim 1, wherein the energy conversion layers comprise GaN. 3. The betavoltaic power source according to claim 1, wherein the energy conversion layers each have a thickness of about 10 microns to 20 microns. 4. The betavoltaic power source according to claim 1, wherein the thermally conducting rods are made of copper. 5. The betavoltaic power source according to claim 1, further comprising a radiation-absorbing shield operably arranged to prevent the beta particles, x-rays and gamma rays from exiting the betavoltaic power source. 6. The betavoltaic power source according to claim 1, wherein adjacent isotope and energy conversion layers define layer pairs and wherein the betavoltaic power source includes between 10 and 250 layer pairs. 7. The betavoltaic power source according to claim 1, wherein the isotope layers are made of the same isotope material. 8. The betavoltaic power source according to claim 1, wherein the amount of electrical energy is at least 200 mw. 9. The betavoltaic power source according to claim 1, wherein the amount of electrical energy is at least 100 mw. 10. The betavoltaic power source according to claim 1, further comprising the mobile device electrically connected to the betavoltaic power source. 11. The betavoltaic power source according to claim 1, wherein one or more of the energy conversion layers have a diode structure. 12. The betavoltaic power source according to claim 11, wherein the diode structure includes either GaN or Ge. 13. The betavoltaic power source according to claim 1, wherein adjacent isotope and energy conversion layers define layer pairs, and wherein the betavoltaic power source includes between 10 and 250 layer pairs. 14. The betavoltaic power source according to claim 1, wherein the radiation includes at least one of beta particles, x-rays and gamma rays. 15. The betavoltaic power source according to claim 1, further comprising a conventional battery electrically connected to the betavoltaic power source.