With growing support from lawmakers, doctors are prodding the medical device industry to design equipment so that it is suitable for use on children. President Bush signed a law in September 2007 that offers financial incentives to companies that design devices for children, and gives regulators more power to scrutinize the use of adult-size devices in children. The profit potential for the device companies is limited, however, because the law allows experimental kid-size devices to be sold without full federal approval only if they're used to treat rare diseases. Also, kids are healthier than adults and as a result a much smaller market to begin with.