Patent ID: 8872408

Claim:
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; and a 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; and wherein the amount of electrical energy generated is at least 10 mW.