Abstract
We report on the fabrication and characterization of an 8 × 8 multichannel Boron Doped Diamond (BDD) ultramicro-electrode array (UMEA). The device combines both the assets of microelectrodes, resulting from conditions in mass transport from the bulk solution toward the electrode, and of BDD's remarkable intrinsic electrochemical properties. The UMEAs were fabricated using an original approach relying on the selective growth of diamond over pre-processed 4 inches silicon substrates. The prepared UMEAs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the electrodes have exhibited a very fast electrode transfer rate (k0) up to 0.05 cm·s−1 (in a fast redox couple) and on average, a steady state limiting current (in a 0.5 M potassium chloride aqueous solution containing 1 mM Fe(CN)64− ion at 100 mV·s−1) of 1.8 nA. The UMEAs are targeted for electrophysiological as well as analytical applications.
Highlights
Microelectrodes exhibit significant advantages over macro-electrode systems, such as a decreased ohmic drop, hemispherical diffusion layer, which extends into the solution, fast establishment of a steady-state signal, and higher S/N ratio
We report a different technological process for the fabrication of diamond UMEAs, which involves the selective growth of diamond over silicon substrates, followed by the deposition of metal contacts and passivation layers
electrochemical impedance spectroscopy (EIS) was recorded over a frequency range of 50 kHz–0.1 Hz with logarithmic point spacing and potential amplitude of 0.01 V∙rms, while the boron doped diamond (BDD) electrode was maintained at open circuit potential. k0 was determined from the Nyquist plot fitted using the ZSimWin 3.21 software
Summary
Microelectrodes exhibit significant advantages over macro-electrode systems, such as a decreased ohmic drop, hemispherical diffusion layer, which extends into the solution, fast establishment of a steady-state signal, and higher S/N ratio. To the authors’ knowledge there is no report on fabrication and characterization of BDD micro-electrode arrays (MEA) and ultra-MEA (UMEA) for systems consisting of an array of 64 multiple electrodes or more, where each electrode is individually connected to a single electrical connector and towards a multichannel readout system Such systems appear extremely useful for electrophysiology applications, where they are used to record the neural signals simultaneously on a 2D network of a cell line culture, a neural tissue or an embryonic organ [16]. We have used electrochemical (EC) characterization techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to appreciate the electrodes performances namely their limiting currents (i lim), electron transfer rates (k0), electrochemical windows and background currents (iBG) etc
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