Directly from NIH STTR Omnibus Solicitation,
grants.nih.gov/grants/guide/pa-files/PA-11-097.html
Eligible Individuals (Project Director/Principal Investigator)
Any individual(s) with the skills, knowledge, and resources necessary to carry out the proposed research as the Project Director/Principal Investigator (PD/PI) is invited to work with his/her organization to develop an application for support. Individuals from underrepresented racial and ethnic groups as well as individuals with disabilities are always encouraged to apply for NIH support.
For the STTR program, the PDs/PIs may be employed with the SBC or the single, “partnering” non-profit research institution as long as s/he has a formal appointment with or commitment to the applicant SBC, which is characterized by an official relationship between the SBC and that individual. Each PD/PI must commit a minimum of 10% effort to the project and the PD/PI must have a formal appointment with or commitment to the applicant small business concern, which is characterized by an official relationship between the small business concern and that individual. Such a relationship does not necessarily involve a salary or other form of remuneration
The SF424 (R&R) SBIR/STTR Application Guide should be referenced for specific details on eligibility requirements. For institutions/organizations proposing multiple PDs/PIs, see Multiple Principal Investigators section of the SF424 (R&R) SBIR/STTR Application Guide.
Additional, information about PD/PI requirements can be found in our FAQs:
grants.nih.gov/grants/funding/sbir_faqs.htm Specifically in section C. 6