Numerical approach to the explanation of the response time of the Severinghaus type electrode

Samukawa, Tsuyoshi; Ohta, Kazuhiro; Onitsuka, M.; Ito, Yasunobu; Motohashi, Ryoichi

doi:10.1016/0003-2670(95)00352-z

Cited by 7 publications

(7 citation statements)

References 5 publications

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“…For example, Xi and Bakker [22] report that, for a shift in CO2 saturation from 0.04% to 0.66%, the Severinghaus probe takes at least 5 min to stabilise to its new potential. Interestingly, this is the probe's 'response time', as the concentration of CO2 has been increased, and it follows, from the work of others [42,43], that the associated recovery time for the probe will be longer, possibly by a factor of 4, which implies a recovery time of ca. 20 min.…”

Section: Drift In Hs Watermentioning

confidence: 95%

“…These response and recovery times are obviously completely inadequate for the monitoring of rapid changes in dissolved CO2, as required for blood gas monitoring for example, where the %CO2 is typically 5%. A Severinghaus electrode for example is often able to respond in a minute, although this can be considerably longer if it possesses a large volume internal bulk electrolyte, or if the concentrations of CO2 are low [22,42,43]. For example, Xi and Bakker [22] report that, for a shift in CO2 saturation from 0.04% to 0.66%, the Severinghaus probe takes at least 5 min to stabilise to its new potential.…”

Section: Drift In Hs Watermentioning

confidence: 99%

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Extruded colour-based plastic film for the measurement of dissolved CO2

Mills

Yusufu

2016

Sensors and Actuators B: Chemical

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Dissolved CO2 measurements are usually made using a Severinghaus electrode, which is bulky and can suffer from electrical interference. In contrast, optical sensors for gaseous CO2, whilst not suffering these problems, are mainly used for making gaseous (not dissolved) CO2 measurements, due to dye leaching and protonation, especially at high ionic strengths (> 0.01M) and acidity (< pH 4). This is usually prevented by coating the sensor with a gaspermeable, but ion-impermeable, membrane (GPM). Herein, we introduce a highly sensitive, colourimetric-based, plastic film sensor for the measurement of both gaseous and dissolved CO2, in which a pH-sensitive dye, thymol blue (TB) is coated onto particles of hydrophilic silica to create a CO2-sensitive, TB-based pigment, which is then extruded into low density polyethylene (LDPE) to create a GPM-free, i.e. naked, TB plastic sensor film for gaseous and dissolved CO2 measurements. When used for making dissolved CO2 measurements, the hydrophobic nature of the LDPE renders the film: (i) indifferent to ionic strength, (ii) highly resistant to acid attack and (iii) stable when stored under ambient (dark) conditions for > 8 months, with no loss of colour or function. Here, the performance of the TB plastic film is primarily assessed as a dissolved CO2 sensor in highly saline (3.5 wt%)water. The TB film is blue in the absence of CO2 and yellow in its presence, exhibiting 50% transition in its colour at ca. 0.18% CO2. This new type of CO2 sensor has great potential in the monitoring of CO2 levels in the hydrosphere, as well as elsewhere, e.g. food packaging and possibly patient monitoring.

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Section: Drift In Hs Watermentioning

confidence: 95%

Section: Drift In Hs Watermentioning

confidence: 99%

Extruded colour-based plastic film for the measurement of dissolved CO2

Mills

Yusufu

2016

Sensors and Actuators B: Chemical

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“…[3][4][5][6][7][8][9] However, drift reported in the literature, ranging up to 20 mV/h, remains a serious problem for practical applications of the sensor. Any drift of the internal pH electrode may cause measurement errors.…”

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confidence: 99%

Electrochemical Sensor for Dissolved Carbon Dioxide Measurement

Yao

Wang

2002

J. Electrochem. Soc.

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In this paper, the fabrication and evaluation of a Severinghaus-type CO 2 sensor, based on an iridium oxide (IrO x ) pH electrode, are described. An iridium oxide pH electrode and an Ag/AgCl reference electrode were housed inside a gas-permeable silicone rubber tubing in which a bicarbonate-based electrolyte solution was sealed. The internal IrO x pH electrode was produced by a new method, i.e., the pH-sensitive IrO x film was coated on the surface of an Ir metal wire by oxidation of the Ir wire in a carbonate melt at high temperature. The Ag/AgCl reference electrode was prepared by chloridizing an Ag wire in a FeCl 3 solution. The CO 2 sensor made this way showed Nernstian response to dissolved CO 2 in the range 10 Ϫ4 to 10 Ϫ2 M. Superior analytical accuracy and stability were observed for the sensor.The concentration of CO 2 in a solution is an important parameter in many biological, biochemical, and industrial processes. Therefore, a sensing technique for dissolved CO 2 is highly desirable. The Severinghaus-type CO 2 sensor is currently the most widely used device for this purpose. This type of sensor consists of a glass pH electrode, a gas-permeable membrane, and a bicarbonate-based internal electrolyte solution. 1,2 The working principle of the CO 2 sensor is based on the measurement of the pH change of the electrolyte solution caused by the hydrolysis of CO 2 . The CO 2 molecules dissolved in the test solution diffuse through the gas-permeable membrane and enter the internal solution, where they react with water to form carbonic acid, which subsequently dissociates into bicarbonate and hydrogen ions ͑see Eq. 1͒. Consequently, the produced hydrogen ions decrease the pH of the electrolyte, which is detected by the internal pH electrodeSince the first Severinghaus-type CO 2 sensor was reported in 1958, 1 many efforts have been made to improve the performance of the sensor including stability, response time, and lifetime. 3-9 However, drift reported in the literature, ranging up to 20 mV/h, remains a serious problem for practical applications of the sensor. Any drift of the internal pH electrode may cause measurement errors. The improvement of the pH electrode is the key to the development of a reliable CO 2 sensor. So far the glass electrode and Sb-SbO x electrode have been mostly used as the internal pH electrodes.Glass electrodes exhibit good sensitivity, stability, and lifetime. However, they are difficult to miniaturize, based on current manufacturing technologies, and cannot be used in food or in vivo applications because of their brittle nature and the risk of leaving sharp bits of glass behind. Furthermore, glass electrodes are expensive and unsuitable for disposable products. The Sb-SbO x electrode suffers from interference by oxygen and shows response drift. We have developed a stable IrO x pH electrode 10,11 and have constructed a Severinghaus-type CO 2 sensor by employing this IrO x electrode as the pH-sensing element. 12 In the present work, we have further improved the CO 2 sensor performance by o...

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“…The lower the PCO 2 value, the slower it gets. Previous numerical simulations have fully characterized this diffusion controlled process. , The lagging behind in the response is not desired when real time monitoring of PCO 2 is needed. Signal drifting will accumulate during the long equilibrating process and contribute also in part to the deviation from the ideal behavior of the Severinghaus CO 2 probe shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…Because it works on the basis of spontaneous diffusion and the establishment of bulk phase equilibrium between the internal compartment and the sample, the response time of the Severinghaus CO 2 probe is typically 1 min or longer. This response time increases with higher inner NaHCO 3 levels. , This slow response of the Severinghaus CO 2 probe has been characterized by numerical simulations and is therefore well understood. , It is not really an adequate tool when rapid real time variations of CO 2 need to be monitored, as in the depth profiling of aquatic systems or the rapid analysis of clinical blood samples.…”

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confidence: 99%

Non-Severinghaus Potentiometric Dissolved CO₂ Sensor with Improved Characteristics

Xie

Bakker

2013

Anal. Chem.

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A new type of carbon dioxide sensor comprising a pH glass electrode measured against a carbonate-selective membrane electrode based on a tweezer type carbonate ionophore is presented here for the first time. No cumbersome liquid junction based reference element is utilized in this measurement. The sensor shows an expected nernstian divalent response slope to dissolved CO(2) over a wide range covering the routine environmental and physiological PCO(2) levels. Unlike the conventional Severinghaus CO(2) probe for which the response is substantially delayed to up to 10 min due to diffusion of carbon dioxide into the internal compartment, the ion-selective CO(2) sensor proposed here shows a response time (t(95%)) of 5 s. When used together with a traditional reference electrode, the sensor system is confirmed to also monitor sample pH and carbonate along with carbon dioxide. A selectivity analysis suggests that Cl(-) does not interfere even at high concentrations, allowing one to explore this type of sensor probe for use in seawater or undiluted blood samples. The CO(2) probe has been used in an aquarium to monitor the CO(2) levels caused by the diurnal cycles caused by the metabolism of the aquatic plants and shows stable and reproducible results.

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Numerical approach to the explanation of the response time of the Severinghaus type electrode

Cited by 7 publications

References 5 publications

Extruded colour-based plastic film for the measurement of dissolved CO2

Extruded colour-based plastic film for the measurement of dissolved CO2

Electrochemical Sensor for Dissolved Carbon Dioxide Measurement

Non-Severinghaus Potentiometric Dissolved CO₂ Sensor with Improved Characteristics

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Numerical approach to the explanation of the response time of the Severinghaus type electrode

Cited by 7 publications

References 5 publications

Extruded colour-based plastic film for the measurement of dissolved CO2

Extruded colour-based plastic film for the measurement of dissolved CO2

Electrochemical Sensor for Dissolved Carbon Dioxide Measurement

Non-Severinghaus Potentiometric Dissolved CO2 Sensor with Improved Characteristics

Contact Info

Product

Resources

About

Non-Severinghaus Potentiometric Dissolved CO₂ Sensor with Improved Characteristics