PDMAEMA/Au (poly(N,N-dimethylaminoethyl methacrylate) covered with gold nanoparticles) modified ITO (indium tin oxide) electrode was synthesized by grafting to method and stimuli responses to pH and ionic strength (IS) was evaluated in PBS solution. At pH<5 PDMAEMA chains were found to be open so [Fe(CN)6]4- were able to reach the surface generating a great electrochemical signal and at pH<5 closed so the signal decreased. In IS<0.005M NaCl polymer chains was open and IS>0.005M NaCl closed. An interesting fact was observed when adding 0.001M NaCl in a pH 7.4 solution, the signal response was increased comparing to pH 7.4 0M NaCl, but when adding 0.001M to a pH 3.00 solution, the signal response was decreased. This behavior can be explained in terms of protonation/deprotonation process and salt blocking properties. PDMAEMA brushes response to pH and IS was confirmed by Localized Surface Plasmonic Resonance measurements. This electrode can be used as a switched ON/OFF pH and IS sensor.