Doctors develop medical devices and are an important source of patents and start-up companies, U.S. researchers say. Sheryl Winston Smith and Andrew Sfekas, both of the Fox School of Business at Temple, analyzed premarket approval applications filed by four medical device companies. Patents from start-up companies founded by physicians were cited more heavily, compared to those from non-physician start-ups. "On average physician-founded companies account for 11 percent, compared with 4 percent from non-physician-founded companies," Smith and Sfekas said.