Okay, but if you really think its stupid, have some fun with it! This is FICTION, not real life.
A pressure sensitive floor alarm could present all kinds of interesting possibilities, most of them probably absurd. BUT as they say, the truth is often stranger than fiction. I'm sure that some designs for burglar alarm systems have been silly or just plain dumb before. That doesn't mean they aren't worth writing about, though.
Sometimes what I do when I write is I begin with a very basic idea or thought. In fact, some of my strongest writing begins that way in concept and as I begin to write to flesh out the idea, I wind up with a piece worth writing home about. (Sometimes, I actually have written home about them, too.) In this case, just let the writing flow from the idea. Try not to be too judgmental of the writing at this stage. Thats what editing is for anyway. So long as the story flows pretty well, you can always make the idea more plausible as you go along either by further enhancing the idea or having it collapse in on itself causing all sorts of problems. While enhancing an idea is the usual route that seems to be taken, I saw a play a few years ago entitled "Well" which took the latter approach of having the play collapse in on itself with riotous effect. Both are possible and limited only by your own imagination.