Gold Microwires Research Articles

Directly Heated Bismuth Film Electrodes Based on Gold Microwires

AbstractAs a nontoxic substitute for mercury electrodes, bismuth electrodes attained a lot of attention during the last years. In this report we describe for the first time the preparation of two different directly heatable bismuth‐modified microwire electrodes. We characterized the electrochemical behaviour using cyclic voltammetry in acetate buffer and alkaline tartrate solution. The bismuth electrodes show a significantly wider potential window compared with bare gold wires. In the presence of picric acid as one example for the detection of explosives, the bismuth electrodes deliver higher signals. By applying heat during the measurements, the signals can be enhanced further. We used the temperature pulse amperometry (TPA) technique to improve the electrochemical response at the different types of electrodes. In this preliminary study, we were able to detect 3 ppm traces of picric acid.

Thermal properties of AlN-based atom chips

We have studied the thermal properties of atom chips consisting o high thermal conductivity Aluminum Nitride (AlN) substrates on which gold microwires are directly deposited. We have measured the heating of wires of several widths and with different thermal couplings to the copper mount holding the chip. The results are in good agreement with a theoretical model where the copper mount is treated as a heat sink and the thermal interface resistance between the wire and the substrate is vanishing. We give analytical formulas describing the different transient heating regimes and the steady state. We identify criteria to optimize the design of a chip as well as the maximal currents $I_c$ that can be fed in the wires. For a 600 $\mu$m thick-chip glued on a copper block with Epotek H77, we find $I_c=16$ A for a 3 $\mu$m high, 200 $\mu$m wide-wire.

Aligned two- and three-dimensional structures by directional freezing of polymers and nanoparticles

The preparation of materials with aligned porosity in the micrometre range is of technological importance for a wide range of applications in organic electronics, microfluidics, molecular filtration and biomaterials. Here, we demonstrate a generic method for the preparation of aligned materials using polymers, nanoparticles or mixtures of these components as building blocks. Directional freezing is used to align the structural elements, either in the form of three-dimensional porous structures or as two-dimensional oriented surface patterns. This simple technique can be used to generate a diverse array of complex structures such as polymer-inorganic nanocomposites, aligned gold microwires and microwire networks, porous composite microfibres and biaxially aligned composite networks. The process does not involve any chemical reaction, thus avoiding potential complications associated with by-products or purification procedures.

Fabrication of gold microtubes and microwires in high aspect ratio capillary arrays.

In this communication, we describe the sequential deposition of materials in capillaries as a means to produce self-assembled three-dimensional gold microtubes, hollow gold microwires, and microtube and microwire arrays with unprecedented aspect ratios. The initial application of this technique is the fabrication of an array of microwires within a silica capillary array. The physical characteristics of these microwires are characterized via SEM, electrochemistry, and electrogenerated chemiluminescence emission.

Flow-through Cell Based on an Array of Gold Microelectrodes Obtained From Modified Integrated Circuit Chips

M. A. Augelli, V. B. Nascimento, J. J. Pedrotti, I. G. R. Gutz and L. Angnes, Analyst, 1997, 122, 843 DOI: 10.1039/A701519D