Development of an optimised coating technique for the functionalisation of micro and nanoelectrodes Rachel Bocking 1 , Thomas Dixon 1 , Prof Helen Picton 2 , Dr Paolo Actis 3 , Dr Robert Menzel 1 1 School of Chemistry, University of Leeds, UK, 2 School of Medicine, University of Leeds, UK 3 School of Electrical & Electronic Engineering, University of Leeds, UK Micro and nanoscale electrodes present an exciting opportunity for the improvement of sensitivity, limit of detection and spatial resolution of electrochemical metabolite sensing measurements. While carbon nanoelectrodes and microelectrodes have been utilised for minimally invasive sensing in tissue 1 , their use in single cell studies remains underexplored due to poor signal-to-noise and selectivity issues. Through modification of these electrodes using high surface area catalytic materials, such as metal nanoparticle-nanocarbon composites, it is possible to achieve even higher sensitivity and tune the selectivity of these sensors. However, traditional coating techniques based on drop-casting are insufficiently precise on micro and nanoscale surfaces and there is evidence that extremely well-dispersed nanocarbons are required to produce non-charging deposits which do not produce excess capacitive currents. 2 Our work presents an adaptable and efficient method that uses a ‘Design of Experiments’ approach to optimise the functionalisation of microelectrodes using electrophoretic deposition, which to the best of our knowledge has not been used before in this context. Three variables were explored: voltage, deposition time and composite concentration, in a 3D design space. The results of this showed that a minimum threshold voltage was required; a further 2D design space was then used at a fixed voltage to further optimise the deposition. This method was applicable across different solvent systems, showing the versatility of this approach for others’ research. The resulting optimised electrode showed reduced capacitive contribution when used for electrochemical sensing, and an improved limit of detection compared to electrodes modified using un-optimised deposition parameters. References 1. P. Actis, S. Tokar, J. Clausmeyer, B. Babakinejad, S. Mikhaleva, R. Cornut, Y. Takahashi, A. L. Cordoba, P. Novak, A. I. Shevchuck, J. A. Dougan, S. G. Kazarian, P. V. Gorelkin, A. S. Erofeev, I. V. Yaminsky, P. R. Unwin, W. Schuhmann, D. Klenerman, D. A. Rusakov, E. V. Sviderskaya and Y. E. Korchev, ACS Nano , 2014, 8 , 875–884. C. B. Jacobs, T. L. Vickrey and B. J. Venton, The Analyst , 2011, 136 , 3557.
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