The aim of this work is to micro-fabricate lead sensors that they will be low powered, cheap to make and easily mass-produced for distribution as hand-held portable devices1 or as long-term deployable devices. Lead is a toxic heavy metal that is linked to several adverse health effects. A report by the WHO identified lead as being responsible for 143,000 deaths annually. As of 2013, the WHO reduced the maximum allowable level of lead in drinking water from 50 ppb to 10 ppb. Microelectrodes fabricated by lithographic techniques on silicon are of great interest as they typically have a higher sensitivity than macroelectrodes of conventional size. This work will specifically focus on interdigitated microelectrodes. Interdigitated electrodes (IDEs) consist of two interlocking combs of electrodes and are typically used as generator-collector electrodes. Generator-collector (GC) electrodes are electrodes in which one side of the array is the generator and the other side of the array is the collector, the analyte of interest reacts at the generator and is converted into a new species which is then collected by the collector electrode and converted back to its original form where it is available again for reaction at the generator. This is known as a redox loop and can help boost the signal and decrease the limit of detection of the analyte. The arrangement of GC electrodes can also be exploited to electrochemically control the local pH of the electrodes. In this instance, the collector is held at a potential where it generates protons that locally change the pH of the solution of surrounding the IDE.2-5 The optimised IDE geometry, GC performance and pH control were all established using simulations carried out in COMSOL Multiphysics® software.The optimised fabricated IDEs were used to carry out analysis for the detection of lead. Unlike most electrochemical reactions where a potential is applied and the reaction of interest occurs, the detection of lead requires a two-step process. The first is a pre-concentration or deposition step where lead is deposited onto the electrode at a constant potential for a certain amount of time, and the second is the stripping step. In the stripping step a graph is obtained plotting current against the potential, the peak current obtained in this graph is proportional to the amount of lead in the sample being analysed. In this work, square wave voltammetry is being used for the stripping step. The detection of lead was further enhanced with nanoporous material,6-8 resulting in a 1.5-fold increase in current for the detection of lead at microelectrodes with nanoporous material compared to planar gold. Analysis of lead in both pH-controlled acetate buffer and tap water indicate the benefit of pH control for the detection of lead. The use of IDEs for pH control are also investigated for further enhanced detection of lead in tap water. Murphy, A; Seymour, I; Rohan, J. F; O’Riordan, A; O’Connell, I; Portable Data Acquisition System for Nano and Ultra-Micro Scale Electrochemical Sensors, IEEE Sensors Journal, 21(3), 2021, 3210-3215, 9186668.Seymour, I; O’Sullivan, B; Lovera, P; Rohan, J. F.; O’Riordan, A; Electrochemical detection of free-chlorine in Water samples facilitated by in-situ pH control using interdigitated microelectrodes, Sensors & Actuators B: Chemical, 2020.O’Sullivan, B; Patella, B; Daly, R; Seymour, I; Lovera, P; Rohan, J. F.; Inguanta, R; O’Riordan, A; A Simulation and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays, Electrochmica Acta, 395, 2021, 139113.Seymour, I; Narayan, T; Creedon, N; Kennedy, K; Murphy, A; Sayers, R; Kennedy, E; O’Connell, I; Rohan, J. F.; O’Riordan, A; Advanced Solid State Nano-electrochemical Sensors and Systems for Agri 4.0 Application, Sensors, 21, 2021, 3149.Seymour, I; O’Sullivan, B; Lovera, P; Rohan, J. F.; O’Riordan, A; Elimination of Oxygen Interference in the Electrochemical Detection of Monochloramine, using in-situ pH Control at Interdigitated Electrodes, ACS Sensors, 6, 2021, 1030.Nagle, L. C.; Rohan, J. F., Nanoporous Gold Catalyst for Direct Ammonia Borane Fuel Cells, Journal of the Electrochemical Society, 2011.Nagle, L.C.; Wahl, A; Ogurstov, V; Seymour, I; Barry, F; Rohan, J. F.; Mac Loughlin, R. Electrochemical Discrimination of Salbultamol from its Excipients in VentolinTM at Nanoporous Gold Microdisc Arrays, Sensors, 21, 2021, 3975.Twomey, K; Nagle, L. C.; Said, A; Barry, F, Ogurstov, V. I.; Characterisation of Nanaoporous Gold for Use in a Dissolved Oxygen Sensing Application, BioNanoSiences, 2015, 5:55-63. Figure 1
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