i e a material with high young 39 s modulus low electrical conductivity and high thermal conductivity the membranes may be fabricated from a material such as sic aln diamond like carbon or tungsten should tungsten be selected a thin layer of electrically insulating material e g sio 2 must be sandwiched between the junction and the l shaped plates to prevent an electrical short circuit nano perforation can be accomplished using a number of techniques such us interference lithography alumina template lithography or block copolymer lithography the second embodiment features an encapsulated engine similar to the one shown in fig7 however the method for maintaining the temperature gradient is different from thermoelectric technology this embodiment uses generic electric micro coolers fig8 shows a detailed partial view of one module 35 this module comprises a perforated radiometric plate 36 and a multiplicity of generic coolers 37 connected in series electrically and in parallel thermally the coolers 37 can exploit any physical principle to achieve high efficiency heat pumping in particular thermionic and or thermotunneling micro coolers may be used this embodiment is an encapsulated radiometric engine similar to the one shown in the first and second embodiments the third embodiment features reinforced radiometric modules instead of simple modules reinforced modules can have a larger surface than simple.