Nano-engineered flexible pH sensor for point-of-care urease detection

A. Sardarinejad; D. K. Maurya; C. Y. Tay; B. J. Marshall; K. Alameh

doi:10.1117/12.2203158

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22 December 2015 Nano-engineered flexible pH sensor for point-of-care urease detection

A. Sardarinejad, D. K. Maurya, C. Y. Tay, B. J. Marshall, K. Alameh

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Proceedings Volume 9668, Micro+Nano Materials, Devices, and Systems; 96684T (2015) https://doi.org/10.1117/12.2203158
Event: SPIE Micro+Nano Materials, Devices, and Applications, 2015, Sydney, New South Wales, Australia

Abstract

Accurate pH monitoring is crucial for many applications, such as, water quality monitoring, blood monitoring, chemical and biological analyses, environmental monitoring and clinical diagnostic. The most common technique for pH measurement is based on the use of conventional glass pH electrodes. Glass electrodes have several limitations, such as mechanical fragility, large size, limited shapes and high cost, making them impractical for implementation as Lab-onchips and pH sensor capsules. Various metal oxides, such as RuO₂, IrO₂, TiO₂, SnO₂, Ta₂O₅ and PdO have recently been proposed for the realization of pH sensing electrodes. Specifically, ruthenium oxide exhibits unique properties including thermal stability, excellent corrosion resistance, low hysteresis high sensitivity, and low resistivity. In this paper, we demonstrate the concept of a miniaturized ion selective electrode (ISE) based pH sensor for point-of-care urease monitoring. The sensor comprises a thin film RuO₂ on platinum sensing electrode, deposited using E-beam and R.F. magnetron sputtering, in conjunction with an integrated Ag/AgCl reference electrode. The performance and characterization of the developed pH/urea sensors in terms of sensitivity, resolution, reversibility and hysteresis are investigated. Experimental results show a linear potential-versus-urea-concentration response for urea concentrations in the range 0 - 180 mg/ml. Experimental results demonstrate super-Nernstian slopes in the range of 64.33 mV/pH - 73.83 mV/pH for RF sputtered RuO₂ on platinum sensing electrode using a 80%:20% Ar:O₂ gas ratio. The RuO₂ sensor exhibits stable operation and fast dynamic response, making it attractive for in vivo use, wearable and flexible biomedical sensing applications.

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A. Sardarinejad, D. K. Maurya, C. Y. Tay, B. J. Marshall, and K. Alameh "Nano-engineered flexible pH sensor for point-of-care urease detection", Proc. SPIE 9668, Micro+Nano Materials, Devices, and Systems, 96684T (22 December 2015); https://doi.org/10.1117/12.2203158

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