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pH-sensitive Ni(OH)/sub 2/-based microelectrochemical transistors

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100291a031· OSTI ID:6629669

Properties of arrays of closely spaced (1.2 ..mu..m) Au or Pt microelectrodes (approx.2 ..mu..m wide x 50 ..mu..m long x 0.1 ..mu..m high) coated with cathodically grown films of Ni(OH)/sub 2/ are reported. Electrical connection of microelectrodes by Ni(OH)/sub 2/ was verified by cyclic voltammetry. The ratio of anodic charge to cathodic charge in cyclic voltammograms for the Ni(OH)/sub 2/ in equilibrium NiO(OH) interconversion exceeds one. However, it is shown that excess charge in the anodic cyclic voltammetric wave for oxidation of Ni(OH)/sub 2/ does not affect the conductivity of Ni(OH)/sub 2/ films. The steady-state resistance of Ni(OH)/sub 2/ connecting two microelectrodes has been measured as a function of potential from 0 to 0.7 V vs. SCE and was typically found to vary from approx.10/sup 7/ to approx.10/sup 4/ ohms. The measured resistance corresponds to a resistivity of approximately 30 ohm cm in the oxidized state. The decrease in resistance is caused by electrochemical oxidation of insulating Ni(OH)/sub 2/ to conducting NiO(OH). At fixed drain voltage, V/sub D/, the gate current, I/sub G/, and the drain current, I/sub D/, can be measured simultaneously as the gate voltage, V/sub G/, is varied at a given frequency. The frequency response is limited by the slow electrochemistry of Ni(OH)/sub 2/ films. At a frequency of 3.8 x 10/sup -2/ Hz, Ni(OH)/sub 2/-based microelectrochemical transistors an amplify electrical power by a factor of 20.

Research Organization:
Massachusetts Institute of Technology, Cambridge
OSTI ID:
6629669
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:7; ISSN JPCHA
Country of Publication:
United States
Language:
English