The STTR program is a similar program to the SBIR program. It also provides federal grant funding to teams working on technologies. The main difference between SBIR and STTR is that the latter requires the small business to be working with a research institute, such as a university, in order to qualify.
Following is the official description of the STTR program on the SBIR.gov website.
"The Small Business Technology Transfer (STTR) is another program that expands funding opportunities in the federal innovation research and development (R&D) arena. Central to the program is expansion of the public/private sector partnership to include the joint venture opportunities for small businesses and nonprofit research institutions. The unique feature of the STTR program is the requirement for the small business to formally collaborate with a research institution in Phase I and Phase II. STTR's most important role is to bridge the gap between performance of basic science and commercialization of resulting innovations."