STANFORD, Calif.--(BUSINESS WIRE)--Nearly everyone knows that the Stanford University School of Medicine is located in Silicon Valley. What’s less widely known is the existence of a “medical device valley” within the same geographic confines — and that Stanford faculty and students played a big part in creating it. More than 200 medical-device companies account for $1.5 billion of the local economy. It’s a force that’s feeding medical advances but also driving medical bills ever higher.