Selective area hydrothermal growth of ZnO nanowires for application to electrochemical sensor

We have developed a simple, low-cost and low-temperature process technique for the selective hydrothermal growth of ZnO nanowires (NWs) on the electrode patterns on the substrate, which can be applied to integrated electrochemical sensor applications. A ZnO seed layer required for hydrothermal growth of ZnO NWs is easily formed selectively on the electrodes for the sensor by low-cost DC electroplating of a Zn layer and subsequent conversion of it into a ZnO layer using oxidation process with a potassium hydroxide (KOH) solution. Selective deposition of a Zn layer at the specific location on the electrode patterns without additional lithographic process is possible by designing electrode patterns properly and making currents flow only through the designated electrodes. In addition, oxidation process using a KOH solution makes it easy to control the surface morphology of the oxidized ZnO layer by simply changing the oxidation time. The feasibility of the developed processing technique has been demonstrated by fabricating an electrochemical sensor platform integrated with a microfluidic channel and experimenting the platform through impedance measurements and cyclic voltammetry (CV) tests using ferricyanide redox material.