nanoCoolers:
"With its patents still pending, NanoCoolers has declined to release details of the metal, except to say it's a mixture comprised predominately of gallium."
http://www.nanocoolers.com/newsroom_detail.php?news_id=16
Maybe it's me, but I couldn't find Gallium listed anywhere else, including their technology section, even when using their search system.....
However.....
US Patent No 6,658,861
"The system as recited in claim 1 wherein the liquid metal contained in the solid-fluid heat exchanger is selected from a group consisting of indium, gallium, mercury, bismuth tin alloy, bismuth lead alloy and sodium potassium eutectic alloy."
"In the preferred embodiment, the liquid metal carried by tube 309 is an alloy of gallium and indium. Preferred compositions comprise 65 to 75% by mass gallium and 20 to 25% indium. Materials such as tin, copper, zinc and bismuth may also be present in small percentages. One such preferred composition comprises 66% gallium, 20% indium, 11% tin, 1% copper, 1% zinc and 1% bismuth. Some examples of the commercially available Gain alloys include galistan--a concoction popular as a substitute for mercury (Hg) in medical applications, and newmerc. The various properties of Ga--In alloy make it desirable liquid metal for use in heat spreaders. The Ga--In alloy spans a wide range of temperature with high thermal and electrical conductivities. It has melting points ranging from -15.degree. C. to 30.degree. C. and does not form vapor at least upto 2000.degree. C. It is not toxic and is relatively cheap. It easily forms alloys with aluminum and copper. It is inert to polyimides, polycarbonates, glass, alumina, Teflon, and conducting metals such as tungsten, molybdenum, and nickel (thereby making these materials suitable for construction of tubes).
However, it is apparent to one skilled in the art that a number of other liquid metals may be used without departing from the scope of the invention. For example, liquid metals having high thermal conductivity, high electrical conductivity and high volumetric heat capacity can be used. Some examples of liquid metals that can be used in an embodiment of the invention include mercury, gallium, sodium potassium eutectic alloy (78% sodium, 22% potassium by mass), bismuth tin alloy (58% bismuth, 42% tin by mass), bismuth lead alloy (55% bismuth, 45% lead) etc. Bismuth based alloys are generally used at high temperatures (40 to 140.degree. C.). Pure indium can be used at temperatures above 156.degree. C. (i.e., the melting point of indium)."
Also see US Patent No 6,708,501
Well, I for one am still confused about the alloy they could possibly be using......