  We demonstrate a local strain sensing method for nanostructures based on
metallic Al tunnel junctions with AlOx barriers. The junctions were fabricated
on top of a thin silicon nitride membrane, which was actuated with an AFM tip
attached to a stiff cantilever. A large relative change in the tunneling
resistance in response to the applied strain (gauge factor) was observed, up to
a value 37. This facilitates local static strain variation measurements down to
~10^{-7}.
