Thanks all for the replies,
To give all some background, the eye of the spring is purely for mounting. The springs parallel legs are inserted and protrude through a piece of moveable piece of metal via a small rectangular hole and an intermediate small worm gear (6mm dia).
The current 'spring' breaks between the worm drive and metal, not at worm drive or metal. We need to get numbers for oscillations of the metal before failure for feedback (arse kick the manufacturer). Currently we find that one leg breaks first
Because the loadings, spring dimensions are so small if any type of mechanical switching is used it could sway the data, searching around I cant find any proximity sensor that is SO small that would pick up the legs individually or a LED slot sensor that would fit in between or around the legs - hence I came back to my question
I just need something that does not impact on the mechanics of the system but could detect 1 or 2 deformations that could ultimately be counted by a uP. Without drawing diagrams and uploading the best analogy I can think of is if you stick 2 fingers out and touched the back of your other hand this is what I want to measure. your hand being the gauge and your finger(s) being the spring leg - would a strain gauge be able to do this?
Thanks