Development of a baseline-temperature correction methodology for electrochemical sensors and its implications for long-term stability

Popoola, Olalekan; Stewart, GB; Mead, Mohammed Iqbal; Jones, R. L.

doi:10.1016/j.atmosenv.2016.10.024

Cited by 112 publications

(95 citation statements)

References 5 publications

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“…Recent work has shown varying rates of drift, ranging from several days (Smith et al, 2017) to many months (Mead et al, 2013;Popoola et al, 2016). We expect to observe a gradual degradation in sensitivity over time as the electrolyte evaporates; the manufacturer (Alphasense Ltd.) quotes a 50 % decay over 2 years.…”

Section: Drift In Sensitivity Over Timementioning

confidence: 99%

“…For context, co-location studies of different electrochemical sensors targeting more abundant pollutants have found correlations with reference instruments (r 2 ) to range between 0.7 and 0.96 for O 3 , NO 2 , NO, and CO (Cross et al, 2017;Jiao et al, 2016;Mead et al, 2013;Popoola et al, 2016;Zimmerman et al, 2017), with estimates of RMSE spanning 4-60 ppb for O 3 (Cross et al, 2017;Sadighi et al, 2017;Spinelle et al, 2015), 4-22 ppb for NO (Cross et al, 2017;Masson et al, 2015), 39 ppb for CO (Cross et al, 2017), and 4.5 ppb for NO 2 (Cross et al, 2017) and estimates of MAE of 38 ppb for CO, 3.5 ppb for NO 2 , and 3.4 ppb for O 3 (Zimmerman et al, 2017). However, it is difficult to directly compare performance metrics (r 2 , RMSE) obtained from the different calibration algorithms taken in these different studies, given the differences not only in sensor types but in also environmental conditions (T , RH, range of pollutant concentrations, and interferences by other pollutants).…”

Section: Algorithm Validationmentioning

confidence: 99%

“…There are multiple advantages to this approach: the reference instruments are regularly calibrated, the reference measurement data are generally made publicly available (e.g., EPA AirNow, US EPA, 2017;OpenAQ, Hasenkopf, 2017), and the calibrations are carried out under ambient conditions that are (at least partially) representative of the sensor measurements to be made. Indeed, the effectiveness of co-location has been demonstrated in several recent studies, with sensor outputs (voltages) and other environmental parameters (e.g., temperature) related to the true concentration values (from the reference instruments) via some form of regression from either parametric models (Jiao et al, 2016;Lewis et al, 2015;Masson et al, 2015;Mueller et al, 2017;Popoola et al, 2016;Sadighi et al, 2017;Smith et al, 2017) or machine-learning/nonparametric methods (Cross et al, 2017;Spinelle et al, 2015;Zimmerman et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…However, accurate calibration of such sensors poses a major challenge. Even setting aside the logistical difficulties associated with calibrating a large number of sensors distributed throughout a network, there are specific technical challenges that can limit the accuracy of any calibration; these include the sensitivity of sensors to environmental conditions (temperature and relative humidity, RH) (Cross et al, 2017;Masson et al, 2015;Mead et al, 2013;Popoola et al, 2016), cross sensitivities to other (sometimes unknown or unmeasured) atmospheric species (Lewis et al, 2015;Mueller et al, 2017;Spinelle et al, 2015;Zimmerman et al, 2017), and long-term sensitivity decay (drift) associated with the evaporation of electrolyte solution (Mead et al, 2013;Smith et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

et al. 2018

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Abstract. The use of low-cost air quality sensors for air pollution research has outpaced our understanding of their capabilities and limitations under real-world conditions, and there is thus a critical need for understanding and optimizing the performance of such sensors in the field. Here we describe the deployment, calibration, and evaluation of electrochemical sensors on the island of Hawai'i, which is an ideal test bed for characterizing such sensors due to its large and variable sulfur dioxide (SO 2 ) levels and lack of other co-pollutants. Nine custom-built SO 2 sensors were colocated with two Hawaii Department of Health Air Quality stations over the course of 5 months, enabling comparison of sensor output with regulatory-grade instruments under a range of realistic environmental conditions. Calibration using a nonparametric algorithm (k nearest neighbors) was found to have excellent performance (RMSE < 7 ppb, MAE < 4 ppb, r 2 > 0.997) across a wide dynamic range in SO 2 (< 1 ppb, > 2 ppm). However, since nonparametric algorithms generally cannot extrapolate to conditions beyond those outside the training set, we introduce a new hybrid linear-nonparametric algorithm, enabling accurate measurements even when pollutant levels are higher than encountered during calibration. We find no significant change in instrument sensitivity toward SO 2 after 18 weeks and demonstrate that calibration accuracy remains high when a sensor is calibrated at one location and then moved to another. The performance of electrochemical SO 2 sensors is also strong at lower SO 2 mixing ratios (< 25 ppb), for which they exhibit an error of less than 2.5 ppb. While some specific results of this study (calibration accuracy, performance of the various algorithms, etc.) may differ for measurements of other pollutant species in other areas (e.g., polluted urban regions), the calibration and validation approaches described here should be widely applicable to a range of pollutants, sensors, and environments.

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Section: Drift In Sensitivity Over Timementioning

confidence: 99%

Section: Algorithm Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

et al. 2018

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“…Not only interfering substances, but also the conditions under which measurements are carried out may affect the work of the electrochemical sensor. Research conducted by Popoola et al and Wu et al indicates that meteorological conditions (temperature and humidity) also have a great influence on measurement [28,29]. This paper presents the results of measurements made with an electrochemical CO sensor.…”

Section: Introductionmentioning

confidence: 91%

The Influence of Hydrogen on the Indications of the Electrochemical Carbon Monoxide Sensors

et al. 2019

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This article examines electrochemical carbon monoxide (CO) sensors used as mobile devices by rescue and firefighting units in Poland. The conducted research indicates that the presence of chlorine (Cl 2 ), ammonia (NH 3 ), hydrogen sulfide (H 2 S), hydrogen chloride (HCl), hydrogen cyanide (HCN), nitrogen (IV) oxide (NO 2 ), and sulfur (IV) oxide (SO 2 ) in the atmosphere does not affect the functioning of the electrochemical CO sensor. In the case of this sensor, there was a significant cross effect in relation to hydrogen (H 2 ). It was found that the time and manner of using the sensor affects the behavior in relation to H 2 . Such a relationship was not recorded for CO. Measurements in a mixture of CO and H 2 confirm the effect of hydrogen on the changes taking place inside the sensor. Independently of the ratio of H 2 to CO, readings of CO were flawed. All analyses showed a significant difference between the electrochemical CO sensor readings and the expected values. Only in experiments with a 1:3 mixture of CO and H 2 was the relative error less than 15%. The relative error in the analyzed concentration range for a sensor with an additional compensation electrode ranged from 7% to 38%; for a sensor without this electrode, it ranged from 23% to 55%. It was ascertained that in the cases of measurements for tests carried out at higher concentrations of H 2 in relation to CO, a sensor with an additional electrode is significantly better (more accurate) than a sensor without such an electrode. Differences at the significance level p = 0.01 for measurements made in the CO:H 2 mixture at a ratio of 1:3 were ascertained.Sustainability 2020, 12, 14 2 of 11 membranes [2,9,10]. The electrodes can be made of various materials. Many kinds of nanoparticles, such as metal, oxide, and semiconductor nanoparticles, have been used for constructing electrochemical sensors [11][12][13][14][15].The electrochemical sensor market is expected to register a Compound Annual Growth Rate of 11.4% over the forecast period 2019-2024. The emergence of nanotechnology-based sensors will drive the market during the forecast period [16].Statistical data indicate that the most common reason for the intervention of emergency services is the suspected release of carbon monoxide. CO is formed as a result of incomplete combustion of carbon and organic substances. As CO is an odorless, tasteless, and colorless gas, it is known as the silent killer. CO poisoning is the most common type of deadly air poisoning in many countries [17]. CO enters the body mainly through the respiratory system, and the amount that enters the body depends on the concentration of CO in the air and the amount of time for which a person breathes polluted air. The most common symptoms include headache, nausea and vomiting, dizziness, lethargy, and a feeling of weakness [18,19]. Health effects associated with exposure to CO range from the more subtle cardiovascular and neurobehavioral effects at low concentrations to unconsciousness and death after acute or chronic exposure to...

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Low-Cost Sensors for Indoor and Outdoor Pollution

Frederickson

Petersen-Sonn

Shen

et al. 2020

Air Pollution Sources, Statistics and Health Effects

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Development of a baseline-temperature correction methodology for electrochemical sensors and its implications for long-term stability

Cited by 112 publications

References 5 publications

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

The Influence of Hydrogen on the Indications of the Electrochemical Carbon Monoxide Sensors

Low-Cost Sensors for Indoor and Outdoor Pollution

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