First-Principles Algorithm for Air Quality Electrochemical Gas Sensors

Ouyang, Bin

doi:10.1021/acssensors.0c01129

Cited by 16 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These methods suffer from "concept drift": that is, the corrections only apply within the range of variables for which they have been derived. 12 Recently, Ouyang, 13 noting that the dependence on ambient humidity, ambient temperature, and the rate of change of both of these created significant difficulties with empirical correction methods, described the use of a second sensor, covered with a Nafion membrane, but otherwise identical, to derive a signal dependent only on the water vapor pressure variations, which could be used to correct the NO 2 sensor signal. The idea was that, irrespective of the mechanism leading to the effects, the effects were on the baseline alone and would be captured by the auxiliary sensor.…”

mentioning

confidence: 99%

Understanding and Correcting Unwanted Influences on the Signal from Electrochemical Gas Sensors

Farquhar¹,

Henshaw²,

Williams

2021

ACS Sens.

View full text Add to dashboard Cite

Humidity- and temperature-dependent errors in concentrations reported by electrochemical sensors for atmospheric nitrogen dioxide significantly limit the reliability of the data. A basic understanding of the source of these errors has been missing. Empirical, software-based corrections are of limited reliability. The sensors feature a 40 wt % (≈4 molal) sulfuric acid electrolyte, and carbon working and quasi-reference (QRE) electrodes. We show that the sensor behaves as a truncated transmission line with resistance and capacitance elements varying with humidity. High-amplitude current fluctuations are due to humidity fluctuations, and are charging currents in response to fluctuations in interfacial capacitance. Baseline currents are due to very small differences in the open-circuit electrode potential between working and reference electrodes. We deduce that acid concentration changes in the meniscus within the porous electrode structure, in response to changes in the ambient temperature and humidity, cause both the capacitance fluctuations and the baseline changes. The open-circuit potential differences driving the baseline current variations are in part due to a difference in the liquid junction potential between the QRE and working electrode, dependent on humidity and temperature and caused by a gradient of acid concentration, and in part due to temperature- and acid-concentration-dependent variations in the rate of the potential-determining reactions. Based on the understanding obtained, we demonstrate a simple hardware change that corrects these unwanted errors.

show abstract

mentioning

confidence: 99%

Understanding and Correcting Unwanted Influences on the Signal from Electrochemical Gas Sensors

Farquhar¹,

Henshaw²,

Williams

2021

ACS Sens.

View full text Add to dashboard Cite

show abstract

“…(i). Electrochemical gas sensors Electrochemical gas sensors are provided with the advantages of high selectivity, strong linearity and low power consumption [29], and common electrochemical sensors include the two-electrode type, three-electrode type, and four-electrode type. The twoelectrode type has a relatively simple structure and only connects to the working electrode and the counter electrode through a load resistance.…”

Section: Sensor Selectionmentioning

confidence: 99%

Design of Gas Monitoring Terminal Based on Quadrotor UAV

Liu

Chen

Fan

et al. 2022

Sensors

View full text Add to dashboard Cite

The problem of air pollution is an increasingly serious worldwide. Therefore, in order to better monitor the gas components in the atmosphere, the design of a gas monitoring terminal based on a quadrotor UAV, including software and hardware design, is hereby carried out. Besides, a pump-suction series cavity is designed to reduce the influence of airflow disturbance on the UAV, which is verified to possess a certain anti-interference ability through Computational Fluid Dynamics(CFD) simulation experiments. In addition, a linear regression algorithm is used for sensor calibration and a polynomial piecewise regression method is used for temperature compensation. The experimental results show that the R2 of the model reaches 0.9981, the fitting degree is rather high, and the output is closer to the real gas concentration value after calibration. At the same time, the temperature compensation parameters are determined, which considerably improves the accuracy of the entire hardware terminal. Finally, the vehicle exhaust monitoring experiment is conducted, and the experimental results show that this scheme can successfully detect the exhaust position of the vehicle exhaust under the interference of the downwash flow of the UAV, thereby proving the reliability and accuracy of the monitoring terminal.

show abstract

“…Second, most of the studies focused on formaldehyde concentration ranges that were higher than typical indoor (~17 ppb) [31] or ambient (~3 ppb) [32] levels in the United States. In addition, previous studies have reported the influence of temperature and RH on the performance of electrochemical sensors [25,[33][34][35][36]. However, some studies report contradictory results regarding the effect of RH [37], and many studies only report qualitative results [30,[38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Laboratory Performance Evaluation of a Low-Cost Electrochemical Formaldehyde Sensor

Pei,

Balitskiy,

Thalman

et al. 2023

Sensors

View full text Add to dashboard Cite

Formaldehyde is a known human carcinogen and an important indoor and outdoor air pollutant. However, current strategies for formaldehyde measurement, such as chromatographic and optical techniques, are expensive and labor intensive. Low-cost gas sensors have been emerging to provide effective measurement of air pollutants. In this study, we evaluated eight low-cost electrochemical formaldehyde sensors (SFA30, Sensirion®, Staefa, Switzerland) in the laboratory with a broadband cavity-enhanced absorption spectroscopy as the reference instrument. As a group, the sensors exhibited good linearity of response (R2 > 0.95), low limit of detection (11.3 ± 2.07 ppb), good accuracy (3.96 ± 0.33 ppb and 6.2 ± 0.3% N), acceptable repeatability (3.46% averaged coefficient of variation), reasonably fast response (131–439 s) and moderate inter-sensor variability (0.551 intraclass correlation coefficient) over the formaldehyde concentration range of 0–76 ppb. We also systematically investigated the effects of temperature and relative humidity on sensor response, and the results showed that formaldehyde concentration was the most important contributor to sensor response, followed by temperature, and relative humidity. The results suggest the feasibility of using this low-cost electrochemical sensor to measure formaldehyde concentrations at relevant concentration ranges in indoor and outdoor environments.

show abstract

First-Principles Algorithm for Air Quality Electrochemical Gas Sensors

Cited by 16 publications

References 31 publications

Understanding and Correcting Unwanted Influences on the Signal from Electrochemical Gas Sensors

Understanding and Correcting Unwanted Influences on the Signal from Electrochemical Gas Sensors

Design of Gas Monitoring Terminal Based on Quadrotor UAV

Laboratory Performance Evaluation of a Low-Cost Electrochemical Formaldehyde Sensor

Contact Info

Product

Resources

About