  The in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin
films at various doping obtained from oxygen reduction has been measured, using
AC susceptibility measurements. For the higher doping samples, the superfluid
density deviates strongly from the s-wave behavior, suggesting, in analogy with
other electron-doped cuprates, a contribution from a nodal hole pocket, or a
small gap on the Fermi surface such as an anisotropic s-wave order parameter.
The low value of the superfluid densities, likely due to a strong
doping-induced disorder, places the superconducting transition of our samples
in the phase-fluctuation regime.
