Total Dissolved Inorganic Carbon Sensor Based on Amperometric CO<sub>2</sub> Microsensor and Local Acidification

Steininger, Fabian; Revsbech, Niels Peter; Koren, Klaus

doi:10.1021/acssensors.1c01140

Cited by 16 publications

(10 citation statements)

References 20 publications

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Section: Resultsmentioning

confidence: 99%

“…Although it takes around ∼3 s slower for the smaller gas sensor to detect the change in the gas concentration, the overall response times for both gas channels are around 5 s or less. This response time is considered fast for a gas sensor working at room temperature ∼22 °C environment, as most gas sensors operating at room temperature have longer response time. ,, …”

Section: Resultsmentioning

confidence: 99%

“…This response time is considered fast for a gas sensor working at room temperature ∼22 °C environment, as most gas sensors operating at room temperature have longer response time. 6,9,55 With the smaller gas sensor which is 65× smaller in volume compared to the bigger gas sensor, we manage to obtain the lowest detection limit of 100 ppm of CO 2 gas concentration and t 90 ∼ 4.7 s, suitable for environmental monitoring. To the best of our knowledge, this is the first demonstration of a functional small NDIR CO 2 gas sensor using a 20% ScAlNbased pyroelectric detector.…”

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confidence: 99%

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Liang

Chen

et al. 2022

ACS Sens.

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NDIR CO 2 gas sensors using a 10-cm-long gas channel and CMOS-compatible 12% doped ScAlN pyroelectric detector have previously demonstrated detection limits down to 25 ppm and fast response time of ∼2 s. Here, we increase the doping concentration of Sc to 20% in our ScAlN-based pyroelectric detector and miniaturize the gas channel by ∼65× volume with length reduction from 10 to 4 cm and diameter reduction from 5 to 1 mm. The CMOS-compatible 20% ScAlN-based pyroelectric detectors are fabricated over 8-in. wafers, allowing cost reduction leveraging on semiconductor manufacturing. Cross-sectional TEM images show the presence of abnormally oriented grains in the 20% ScAlN sensing layer in the pyroelectric detector stack. Optically, the absorption spectrum of the pyroelectric detector stack across the mid-infrared wavelength region shows ∼50% absorption at the CO 2 absorption wavelength of 4.26 μm. The pyroelectric coefficient of these 20% ScAlN with abnormally oriented grains shows, in general, a higher value compared to that for 12% ScAlN. While keeping the temperature variation constant at 2 °C, we note that the pyroelectric coefficient seems to increase with background temperature. CO 2 gas responses are measured for 20% ScAlN-based pyroelectric detectors in both 10-cm-long and 4-cm-long gas channels, respectively. The results show that for the miniaturized CO 2 gas sensor, we are able to measure the gas response from 5000 ppm down to 100 ppm of CO 2 gas concentration with CO 2 gas response time of ∼5 s, sufficient for practical applications as the average outdoor CO 2 level is ∼400 ppm. The selectivity of this miniaturized CO 2 gas sensor is also tested by mixing CO 2 with nitrogen and 49% sulfur hexafluoride, respectively. The results show high selectivity to CO 2 with nitrogen and 49% sulfur hexafluoride each causing a minimum ∼0.39% and ∼0.36% signal voltage change, respectively. These results bring promise to compact and miniature low cost CO 2 gas sensors based on pyroelectric detectors, which could possibly be integrated with consumer electronics for real-time air quality monitoring.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Liang

Chen

et al. 2022

ACS Sens.

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“…This could be via featuring sensor interfaces that contain certain materials (e.g., toxic metals) or by releasing chemicals. Recent examples are two sensors developed by Steininger et al for dissolved inorganic carbon (DIC) 24 and total dissolved sulfide (TDS). 25 Both sensors use an electrochemical microsensor as transducer measuring CO 2 or H 2 S respectively.…”

Section: ■ the Current Best Practicementioning

confidence: 99%

Let’s Talk about Slime; or Why Biofouling Needs More Attention in Sensor Science

Koren

McGraw

2023

ACS Sens.

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Although there is a growing demand for new sensors for environmental monitoring, biofouling continues to plague current sensors and sensing networks. As soon as a sensor is placed in water, the formation of a biofilm begins. Once a biofilm is established, reliable measurements are often no longer possible. Although current biofouling mitigation strategies can slow the biofouling process, a biofilm will eventually develop on or near the sensing surface. While antibiofouling strategies are being continuously developed, the complexity of the biofilm community structure and the surrounding environment means that there is unlikely to be a single solution that will minimize biofilms on all environmental sensors. Thus, antibiofouling research often focuses on optimizing a specific biofilm mitigation approach for a given sensor, application, and environmental condition. While this is practical from the standpoint of a sensor developer, it makes the comparison of different mitigation strategies difficult. In this Perspective, we discuss the application of different biofouling mitigation strategies to sensing and then explore the need for the sensor community to adopt standard protocols to increase the comparability of the biofouling mitigation approaches and help sensor developers identify the most appropriate strategy for their system.

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“…A recent work proposed the implementation of an outer acidic conversion chamber with an amperometric CO 2 microsensor . Passive diffusion-based acidification generated the in situ conversion of inorganic carbonates to measurable CO 2 .…”

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Imaging of CO₂ and Dissolved Inorganic Carbon via Electrochemical Acidification–Optode Tandem

et al. 2023

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Dissolved inorganic carbon (DIC) is a key component of the global carbon cycle and plays a critical role in ocean acidification and proliferation of phototrophs. Its quantification at a high spatial resolution is essential for understanding various biogeochemical processes. We present an analytical method for 2D chemical imaging of DIC by combining a conventional CO2 optode with localized electrochemical acidification from a polyaniline (PANI)-coated stainless-steel mesh electrode. Initially, the optode response is governed by local concentrations of free CO2 in the sample, corresponding to the established carbonate equilibrium at the (unmodified) sample pH. Upon applying a mild potential-based polarization to the PANI mesh, protons are released into the sample, shifting the carbonate equilibrium toward CO2 conversion (>99%), which corresponds to the sample DIC. It is herein demonstrated that the CO2 optode–PANI tandem enables the mapping of free CO2 (before PANI activation) and DIC (after PANI activation) in complex samples, providing high 2D spatial resolution (approx. 400 μm). The significance of this method was proven by inspecting the carbonate chemistry of complex environmental systems, including the freshwater plant Vallisneria spiralis and lime-amended waterlogged soil. This work is expected to pave the way for new analytical strategies that combine chemical imaging with electrochemical actuators, aiming to enhance classical sensing approaches via in situ (and reagentless) sample treatment. Such tools may provide a better understanding of environmentally relevant pH-dependent analytes related to the carbon, nitrogen, and sulfur cycles.

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Total Dissolved Inorganic Carbon Sensor Based on Amperometric CO₂ Microsensor and Local Acidification

Cited by 16 publications

References 20 publications

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Let’s Talk about Slime; or Why Biofouling Needs More Attention in Sensor Science

Imaging of CO₂ and Dissolved Inorganic Carbon via Electrochemical Acidification–Optode Tandem

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Total Dissolved Inorganic Carbon Sensor Based on Amperometric CO2 Microsensor and Local Acidification

Cited by 16 publications

References 20 publications

Miniaturized CO2 Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO2 Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Let’s Talk about Slime; or Why Biofouling Needs More Attention in Sensor Science

Imaging of CO2 and Dissolved Inorganic Carbon via Electrochemical Acidification–Optode Tandem

Contact Info

Product

Resources

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Total Dissolved Inorganic Carbon Sensor Based on Amperometric CO₂ Microsensor and Local Acidification

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Miniaturized CO₂ Gas Sensor Using 20% ScAlN-Based Pyroelectric Detector

Imaging of CO₂ and Dissolved Inorganic Carbon via Electrochemical Acidification–Optode Tandem