Fabrication of Microelectrode Arrays

Numerous methods for fabricating microelectrode arrays have been devised depending on the type of array required (6, 20, 35,41, 49, 62, 63, 65, 115-134). 

Low-aspect-ratio (ratio of the height of the microelectrode divided by its lateral dimension is larger than 0.2) microelectrode arrays are fabricated using conventional silicon-based microfabrication technologies, such as hthographic techniques to yield arrays of thin films of metallic or carbon electrodes on a silicon substrate. These arrays often have limited stability and life times as a result of defects in the metal layer poor resistance to corrosion is 

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Thiebaud P (1999) Fabrication of microelectrode arrays for electrophysiologictil monitoring of hippocampal organotypic slice cultures by interface. In Institute of Microtechnology PhD. Neuchatel University of Neuchatel. 

Preparation of Microelectrode Arrays. The microelectrode arrays used in the work were arrays of microelectrodes each 80 pm long, 2.3pm wide and 0.1 pm thick and 3paced 1.7 pm apart. Fabrication and encapsulation of the microelectrode arrays has been described previously.<14.15.21-22) Prior to use, arrays of microelectrodes were cleaned by an rf 02 plasma etch to remove residual photoresist, followed by cycling the potential of each electrode between -1.5 V... 

J. Pritchard, L.A. Law, A. Vakurov, P. Millner and S.P.J. Higson, Sonochemically fabricated enzyme microelectrode arrays for the environmental monitoring of pesticides, Biosens. Bioelectron, 20 (2004) 765-772. 

Pritchard et al. [131] describe the development of a single thiocholine enzyme-based biosensor. This biosensor is a sonochemically fabricated enzyme microelectrode array in order to impart stir-independent (convection) responses that are characteristic of microelectrodes. Microelectrode arrays with up to 2 x 10 microelectrode elements may be fabricated via the sonochemical ablation of noncondnc-tive polymer films [132,133], which coat and thereby insnlate nnderlying condnctive snrfaces [134]. Paraoxon is determined down to concentrations of 1 x 10 M via the nse of sonochemically fabricated acetylcholine/polyaniline microelectrode array-based sensors. These sensors were fabricated via the electropolymerization of thin... 

H. P. Wu. Fabrication and characterization of a new class of microelectrode arrays exhibiting steady-state current behavior, Anal. Chem. 65, 1643-1646 (1993). 

Kittlesen, G.P., H.S. White, and M.S. Wrighton. 1984. Chemical derivativization of microelectrode arrays by oxidation of pyrrole and N-methylpyrrole Fabrication of molecule-based electronic... 

One of the earliest applications of the template method was to prepare ensanble miCTo-scopic (7, 18) and nanoscopic electrodes (116, 141). Such electrodes were prepared by electrochemically depositing noble metals within the pores of the commercially available polymeric filtration membranes. The fabrication of a microelectrode ensemble based on the electrochemical deposition of platinum into the pores of a track-etched microporous polycarbonate host membrane was first shown in 1987 by Charles Martin (7). The word ensemble was used to describe the final device because the elements in the device are not evenly spaced. The procedure is simple, and requires only routine and inexpensive electrochemical instrumentation. It was ultimately found that electroless plating allowed for more uniform metal deposition (116). Both plating methods are important for the fabrication of the array, and further considerations continue in the following. 

All these array geometries show peculiar electrochemical behavior which can be properly exploited for electroanalytical purposes. The goal of this chapter is to give an overview of the different types of micro- and nanoelectrodes arrays (ensembles, ordered, interdigitated, etc.) as well as a brief description of the main techniques used for their fabrication. Note that in most cases the fabrication of nanoelectrodes arrays requires more specialized fabrication techniques with respect to microelectrode arrays, and therefore they will be presented separately. Specific electrochemical properties of micro and nanoelectrodes arrays will be described in relation to the specific diffusion mechanisms observed in such electrochemical sensors. 

Photolithography is the most diffused technique for the fabrication of regular arrays of microelectrodes. Photolithography is a microfabrication technique which is based on the selective removal of parts of thin films (photoresist) exposed to UV light. This procedure allows one to obtain regular arrays of micro electrodes with high spatial resolution, nonetheless this technique requires special and expensive equipments besides, the photolithographic process requires access to a clean room. 

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