I would like to electronically measure the width (really the compression/extension) to which an object's constituent blades have been stretched. Or alternatively, I could measure some other parameter which I can then map to the displacement by data calibration.
In particular, I am dealing with a miniature tool (a few cm long) whose outline resembles an alligator-clip (or pliers). So consider something like either of the objects in the below image.
How can I electronically track/measure the below spacing to a resolution of about 0.1 mm over a full-scale extent of ~10 mm?
I cannot think of any transducer or phenomenon that I could map to this movement and get such fine resolution. For example:
Perhaps I can measure parallel-plate capacitance -- would that be accurate enough in this scenario?
Or maybe I could place a spring between the two jaws and measure the compression -- but how would I measure the compression of the spring?
CV isn't a viable option because I wish to make the sensor compact enough that that I can log the data wherever I wish.
EDIT: Updated with illustration added based on @Michael Karas's Answer and @Matt Young's suggestion.