This may be a stupid question!

Are speed, cadence, heart-rate sensors interchangeable among manufacturers? I'm asking because I am currently checking out an iBike Power Meter (the latest Newton) and I've had problems with the wireless sensors dying out on me....for instance, I have a combination speed/cadence sensor. It uses one battery with the cadence sensor connected to the speed sensor with a wire. Well I've 'broken' 2 of these - maybe it was water infiltration, I'm not sure. They're abut 50 bucks to replace.

I was looking for used ones on eBay and came across a few other brands which look similar (i.e. Wahoo). So my question is: will other manufacturer's speed/cadence sensor work with my iBike Newton? And if not, why?

thanks