Electronic semiconducting oxides as pH sensors

Fog, Agner; Buck, Richard P.

doi:10.1016/0250-6874(84)80004-9

Cited by 391 publications

(301 citation statements)

References 9 publications

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“…All types of reference electrodes were tested in order to compare their performance and select the most suitable ones for oil acidity measurements. RuO 2 working electrode has been shown to have the highest sensitivity to pH changes compared to any other metal oxide tested in aqueous solutions 25,26 .…”

Section: Thick Film Acidity Sensors and Oil Acidity Measurementsmentioning

confidence: 99%

Base oil oxidation detection using novel chemical sensors and impedance spectroscopy measurements

Soleimani

Sophocleous

Wang

et al. 2014

Sensors and Actuators B: Chemical

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Lubricating oils are employed in machinery to minimise friction, remove heat and wear particles, protect against corrosion etc. Mineral base oils are derived from natural crude oil through a distillation process and are divided into five main groups depending on volume of sulphur, saturate and viscosity index, according to the American Petroleum Institute (API). As lubricating base oil oxidises, acidic by-products are formed and oil viscosity increases due to progressive polycondensation of higher molecular weight products. In this work, thick film (TF) potentiometric sensors based on ion-selective electrodes (ISE) have been developed for oil acidity measurement to enable online oil condition monitoring. A TF ruthenium oxide (RuO 2 ) working electrode and three types of TF reference electrodes were fabricated and tested in oxidised base oil samples prepared at the Shell Houston laboratories. The TF sensors were evaluated by comparison with acid number (AN) measurement and also compared with oil conductivity measurements using impedance spectroscopy. The results show that the conductivity, viscosity and AN of the oil samples increase with the level of oil oxidisation. The output of the TF sensors detected the acidity increase of the oxidised oil samples at both 50 and 80 °C and displayed a linear relationship with oil AN.

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Section: Thick Film Acidity Sensors and Oil Acidity Measurementsmentioning

confidence: 99%

Base oil oxidation detection using novel chemical sensors and impedance spectroscopy measurements

Soleimani

Sophocleous

Wang

et al. 2014

Sensors and Actuators B: Chemical

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“…Fog and Buck proposed and discussed five different possible explanations of the pH response mechanisms of metal oxides and suggested that the most probable theory was that of oxygen intercalation [5,8,9]. This mechanism is represented by the equilibrium reaction:…”

Section: Ph Sensor Theorymentioning

confidence: 99%

Performance of miniaturised thick-film solid state pH sensors

Glanc-Gostkiewicz

Sophocleous

Atkinson

et al. 2013

Sensors and Actuators A: Physical

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The performance of novel solid state Thick-Film pH sensors for water quality sampling that are designed for deployment in remote catchment areas is described. These miniaturised screen printed planar pH sensors are an alternative to conventional glass pH electrodes that have many disadvantages such as high-cost, large size, mechanical fragility and limited shape. The approach adopted here for improvement of the ruggedness of the pH electrode is through its implementation as a screen printed metal oxide (RuO 2 ) ion selective electrode used in combination with a screen printed silver/silver chloride (Ag/AgCl) reference electrode. Various choices of materials have been evaluated for the fabrication of the Thick-Film pH sensors resulting in a device with a sensitivity of approximately 30mV/pH at ambient temperature.

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“…Nernstian behaviour is demonstrated by the electrode when the measured electrode potential decreases by 59 mV for every decade change in Cl − concentration at room temperature of 25 °C. Fog and Buck proposed five possible interpretations for the pH response mechanism of metal oxides, with the most recognized theory being oxygen intercalation [25]. The following equilibrium reaction represents the oxygen intercalation mechanism:…”

Section: Ph Sensing Mechanismmentioning

confidence: 99%

“…In recent years, a number of metal oxides based pH sensors have been developed incorporating IrO2 [16][17][18][19], RuO2 [20][21][22][23][24], PtO2 [25], SnO2 [25], TaO2 [25], TiO2 [25,26] and Ta2O5 [27,28]. pH sensors have been developed using a variety of deposition techniques including magnetron sputtering [20][21][22], sol-gel [17,29], screen-printing [24,30] and plasma enhanced chemical vapour deposition (PECVD) [31,32] and electroplating [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Recent Developments in R.F. Magnetron Sputtered Thin Films for pH Sensing Applications—An Overview

2014

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pH sensors are widely used in chemical and biological applications. Metal oxides-based pH sensors have many attractive features including insolubility, stability, mechanical strength, electrocatalyst and manufacturing technology. Various metal oxide thin films prepared by radio frequency (R.F.) magnetron sputtering have attractive features, including high pH sensitivity, fast response, high resolution, good stability and reversibility as well as potential for measuring pH under conditions that are not favourable for the commonly used glass electrodes-based pH sensors. In addition, thin film pH sensors prepared by R.F. magnetron sputtering offer many advantages, such as ease of packaging, low cost through the use of standard microfabrication processes, miniaturisation, capability of measuring pH at high temperatures, ruggedness and disposability. In this paper, recent development of R.F. magnetron sputtered thin films for pH sensing applications are reviewed.

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Electronic semiconducting oxides as pH sensors

Cited by 391 publications

References 9 publications

Base oil oxidation detection using novel chemical sensors and impedance spectroscopy measurements

Base oil oxidation detection using novel chemical sensors and impedance spectroscopy measurements

Performance of miniaturised thick-film solid state pH sensors

Recent Developments in R.F. Magnetron Sputtered Thin Films for pH Sensing Applications—An Overview

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