On-demand protection of electrochemical sensors based on adaptive nanowires

We report here on the use of adaptive nanowires for addressing the key surface fouling problem of electrochemical sensors. Effective resistance against surfactant fouling is obtained by switching magnetically the surface orientation of alkanethiol-coated gold nanowires (containing a short nickel segment) between horizontal and vertical positions to allow the transducer to perform the measurement and reset it to the protection mode between successive measurements. This leads to "opening" and "closing" of the surface and hence switching between active (sensing) and passive (protection) modes. Such on-demand protection and minimization of surface-fouling are indicated from prolonged series of stripping-voltammetric measurements of cadmium in the presence of gelatin, albumin, or Tween80. Factors influencing the protective action of the adaptive nanowires, including the length of the alkanethiol layer or of the gold/nickel segments were examined and optimized. Such on-demand protection capability should facilitate practical sensing applications of electrochemical devices.