Nanofabrication of Robust Nanoelectrodes for Electrochemical Applications

Abstract

Individual gold nanowire devices for use as nanoelectrodes in electrochemical studies were fabricated using a low-cost robust fabrication approach.Nanowires were characterized by a combination of direct electrical current-voltage measurements and cyclic voltammetry using the model analyte ferrocene monocarboxylic acid. We observed low electrical resistances to contacted nanowires and steady-state sigmoidal electrochemical voltammograms that may be described by classical Butler-Volmer kinetics. The potential of nanowires for use in future biosensing applications was explored by demonstrating mediated bioelectrocatalytic oxidation of glucose.The growing need for point of care (POC) technologies is driving the development of more sensitive and more advanced sensor devices, particularly nanosensors. POC technologies are becoming more pervasive and range from the simple home pregnancy test kit to more complex blood analyzers employed in emergency clinical environments. With the global nanosensor market expected to exceed $2.4 billion by 2012 a number of blue chip companies are establishing market positions (1). To win a market share new emerging POC technologies must provide: convenience, rapid analysis (less than 5 minutes), ease of use, assay detection limits equivalent to or better than established clinical laboratory assays, at low cost (less than $10 per assay) and have low maintenance requirements. To this end, significant opportunity therefore exists to develop new sensor devices that exploit low cost nano-manufacturing methods. To address this opportunity, nanosensors based on 1-D nanostructures such as silicon nanowires and carbon nanotubes are being explored as theses nanostructures offer the potential to achieve highlyintegrated sensors with direct electrical readout (2-4). In these sensor systems, the perturbation in the local electrostatic environment of a nanowire-based field effect transistor by a charged analyte causes an increase or decrease in conductance, which is employed as the sensor signal (2). Although elegant, these sensor technologies require complex heterogeneous integration approaches following synthesis and, depending on device architecture, may require the application of back gate voltages as high as 40 V to be applied (5).By contrast, electrochemical sensors typically have much lower voltages (-1.5 -1.5 V) requirements. Compared to traditional macroelectrodes, nanoscale electrodes have tremendous potential as electrochemical sensors exhibiting enhanced performance. As critical dimensions of the electrodes enter the micro and nano regime, radial analyte diffusion profiles dominate with a corresponding increase in mass transport rate, higher current densities giving rise to an increased I F /I C ratio (due to smaller surface area), higher S/N ratios and steady-state sigmoidal voltammograms. (6). However, widespread

An Electrochemical Screen-Printed Sensor Based on Gold-Nanoparticle-Decorated Reduced Graphene Oxide–Carbon Nanotubes Composites for the Determination of 17-β Estradiol

“…The electrochemical active surface area of rGO-AuNPs/CNT was calculated using Equation (1) for the peak current (Ip) [ 74 ]: I p = (2.69 × 10 5 ) AD 1/2 n 3⁄2 v 1⁄2 C where n is the number of electrons, A is the electroactive surface area of the rGO-AuNPs/CNT/SPE (cm 2 ), D is the diffusion coefficient of the redox marker [Fe(CN) 6 ] −3/−4 ( D = 7.2 × 10 −6 cm 2 s −1 [ 74 , 75 ] in 0.1 M KCl), C is the concentration of the redox probe in the solution (M), and v is the scan rate (V/s). Figure 4 A shows an increase in the peak currents for the [Fe(CN) 6 ] 4−/3− redox couple at the rGO-AuNPs/CNT/SPE compared to that at the bare, unmodified SPE.…”

Review—Electrolytic Metal Atoms Enabled Manufacturing of Nanostructured Sensor Electrodes

“…Nanostructured electrodes not only have high surface areas and high catalytic activity but also provide very special environments to electrochemical reactions. 39,[153][154][155] Compared to planar electrodes, the reactant molecules have increased chance to interact with electrode surfaces and the surface species could stay longer on electrode surfaces. Furthermore, the nanostructures resulted nano-confinement effects can prevent reactive molecules and reactive intermediates escaping back to bulk solution.…”

Glucose Detection at Single Gold Nanowires

“…. [3][4][5][6] We explore the application of single on-chip gold nanowires for use as electrochemical sensors employing glucose as target molecule.…”