In November, City Labs, which makes tiny batteries that can last more than 20 years, signed a contract with the U.S. Air Force Research Laboratory worth nearly $1 million. The company’s NanoTritium battery, which hit the market in 2008, is powered by proprietary technology and the radioactive hydrogen isotope Tritium (currently used to illuminate exit signs). City Labs was formed by two Miami entrepreneurs in 2005 and last November moved into Homestead’s Carrie P. Meek Business Center incubator. It also completed its first round of fundraising, with an investment led by Alex Aguila, co-founder of specialty computer maker Alienware. In January, the company became the first in the industry to receive a license to manufacture, sell and distribute betavoltaic batteries like its NanoTritium.