Well, if he's that interested and you don't think he's just pretending to be interested, I'd give him a tour of your pump. He may be the next guy to go into medical technology or medical research and create a big break-through. I'm sure Paul Allen, Steve Jobs and Bill Gates were all really annoying science and technology geeks in high school (Google their pictures some time!) but how many lives have they changed? How many technological advances have they been involved in?
Then again, maybe he just thinks you're really cute? ;0)