Stephen O’Connor is equal parts scientist, engineer and salesman. Armed with a PhD in chemistry from Caltech and more than a dozen jointly held patents, he helped start four companies, raising most of the seed money himself. His first venture made ultrafast optical sensors. His second, Clinical Microsensors, made DNA detection instruments he designed to quickly read the genetic makeup of plant and animal tissue; Motorola bought the company for $300 million. Money and experience gave O’Connor the confidence to found Nanostream in Pasadena, CA, in 1999.It makes custom chips that analyze microscopic amounts of blood or other fluids,some of the first commercial products in the rapidly growing field of microfluidics. With $11 million in funding, Nanostream markets the chips topharmaceutical companies for drug discovery tests. Also in 1999,O’Connor founded CO2,a profitable incubator company that has invested in 11 local scientific startups by outfitting their labs.O’Connor’s Caltech advisor, John Baldeschwieler, says his ex-student is “playing an increasingly important role in the economic development of Pasadena.”