Balloon switch

Submitted by Luigi A on July 20, 2007 - 4:35pm.

Well, here I am: first post! I wanted to share my first squeezable switch that I am proud of. It's a balloon switch largely based on the "glove switches" Karen and Mike showed us as we were starting to work on prototyping stuff. It has stuffing inside of the balloon to keep it constantly inflated (that was a neat trick!), and works very similarly to what has already been done: the air is pushed inside of a tambour (a membrane stretched over a frame), making it billow and in the process completing a circuit. The part that I am proud of is that I managed to keep the size of the tambour very small: it's made out of one half of a contact lens carrier case. Here's a picture of the detail of the tambour: A piece of balloon is stretched over the bottom of the case, and secured with a zip tie. A piece of conductive tape on top of it is one of the contacts. Aluminum foil against the top half provides the other contact. The whole thing is surprisingly reliable and sturdy, Most importantly, it satisfies two main requirements I had in mind for my "perfect switch". Most soft toys that have switches inside of them actually have a hard piece of plastic that you can feel through the material: I didn't want that. I wanted a switch that was actually entirely soft to squeeze, yet had some feedback in it, that felt like it was resisting the squeezing a little bit. The stuffed balloon accomplishes that. Also, I wanted the whole thing to be small enough that it could actually be built inside a medium-sized stuffed toy, without weird wires coming out: the small tambour accomplishes that. So all in all I'm pretty happy with it, although I think it took me the better part of a morning to get it to work.