The Effect of the Orientation Towards Analyte Flow on Electrochemical Sensor Performance and Current Fluctuations

Sedlák, Petr; Kuberský, Petr

doi:10.3390/s20041038

Cited by 13 publications

(13 citation statements)

References 33 publications

(43 reference statements)

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“…The current fluctuations represent macroscopically a number of physical and chemical stochastic processes taking place in charge transport across the electrochemical device. Researchers use fluctuation analysis to extract more information about these processes [33][34][35][36][37] . In another words, noise spectroscopy gives integral information about a whole state of the electrochemical device and may inform about issues in a design of device, a quality of electrical contacts, long-term stability, degradation of electrochemical interface.…”

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confidence: 99%

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

Sedlák

Gajdoš

Macků

et al. 2020

Sci Rep

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The experimental study deals with the investigation of the effect of diverse crystallinity of imidazolium ionic-liquid-based SPE on conductivity and current fluctuations. The experimental study was carried out on samples consisting of [EMIM][TFSI] as ionic liquid, PVDF as a polymer matrix and NMP as a solvent. After the deposition, the particular sample was kept at an appropriate temperature for a specific time in order to achieve different crystalline forms of the polymer in the solvent, since the solvent evaporation rate controls crystallization. The ac/dc conductivities of SPEs were investigated across a range of temperatures using broadband dielectric spectroscopy in terms of electrical conductivity. In SPE samples of the higher solvent evaporation rate, the real parts of conductivity spectra exhibit a sharper transition during sample cooling and an increase of overall conductivity, which is implied by a growing fraction of the amorphous phase in the polymer matrix in which the ionic liquid is immobilized. The conductivity master curves illustrate that the changing of SPEs morphology is reflected in the low frequency regions governed by the electrode polarization effect. The dc conductivity of SPEs exhibits Vogel–Fulcher–Tammann temperature dependence and increases with the intensity of thermal treatment. Spectral densities of current fluctuations showed that flicker noise, thermal noise and shot noise seems to be major noise sources in all samples. The increase of electrolyte conductivity causes a decrease in bulk resistance and partially a decrease in charge transfer resistance, while also resulting in an increase in shot noise. However, the change of electrode material results in a more significant change of spectral density of current fluctuations than the modification of the preparation condition of the solid polymer electrolyte. Thus, the contact noise is considered to contribute to overall current fluctuations across the samples.

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confidence: 99%

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

Sedlák

Gajdoš

Macků

et al. 2020

Sci Rep

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“…In terms of sensitivity, sensors placed perpendicular to the gas flow could perform better than the parallel ones as reported previously. [19] Perpendicular installation of sensors, however, has several drawbacks, such as potential interruption of the gas flow by the sensors and challenges associated with making electrical connections to the sensors, which may increase the risk of channeling effect and thus the degradation of filtration capability. Hence, in this work we chose to place the sensors parallel to the gas flow.…”

Section: Resultsmentioning

confidence: 99%

Design and Integration of a Gas Sensor Module that Indicates the End of Service Life of a Gas Mask Canister

Moon

Lee

Min

et al. 2021

Adv Materials Technologies

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adsorbent material has limited adsorption capacity, the chemical cartridge or the filter needs to be replaced before the adsorption capacity is exceeded. End of service life indicator (ESLI), a system that informs the users as to when to replace the filter, has been widely employed in consumer products such as air conditioners and water/air purifiers. For these products, replacing the filters on time is advisable but not mandatory. By contrast, for the filtration of toxic gases, such as chemical warfare agents (CWAs) and toxic industrial chemicals (TICs), the expired filter must be promptly replaced for the safety of the users. Developing an ESLI in those systems, however, has been sluggish. [2] ESLI for filtration of CWAs is not available, and ESLI developed for canisters against TICs uses colorimetric sensors that are slow and have low sensitivity as compared to electronic sensors. Occupational Safety and Health Administration (Department of Labor, USA) presents a guideline for replacing the filter based on mathematical models, [3] whose input parameters are the type of gases, and their concentrations, temperature, humidity, flow rate, etc. Application of such models, however, is not practical as the parameters not only are difficult to measure but also vary In a filtration system, a chemical cartridge packed with porous adsorbents needs to be replaced when its maximum adsorption capacity is exceeded. An end of service life indicator (ESLI) informs when to replace the cartridge. However, ESLI technology for filtration of toxic gases is overlooked despite high toxicity of the gases even at low concentrations. In this study, a real-time ESLI is demonstrated for filtration of chemical warfare agents by inserting four chemiresistors made of carbon nanotubes into the adsorbent layer of a canister for gas masks. The sensors are installed on a flexible printed circuit board with a 3D structure to minimize the channeling effect in the canister. As the breakthrough of dimethyl methylphosphonate, a nerve agent simulant, progresses in the canister, the resistance of the sensors increases sequentially with time. The inflection points in the responses from sensors designated #1-#4 indicate that the percentage of remaining service life is 75%, 50%, 25%, and 0%, respectively. The ESLI potentially applies to a wide range of toxic gases and cartridge designs, regardless of the sensitivity and selectivity of the sensors, as supported by the breakthrough of ammonia as well as the results from a smaller canister.

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“…Figure 3 shows the spectral densities of current fluctuations depending on NO2 concentrations, as the SPEs of sensors were prepared under different treatment conditions. At zero concentration, power spectra exhibit thermal noise, which is associated with all dissipative processes across the sensor and corresponds to the real part of electrical impedance of the sensor, and either the f −1.25 noise component, which should indicate diffusion-dominant electrode-electrolyte interface [13,[15][16][17], or the f −2.00 noise component, which should indicate drift-dominant electrode-electrolyte interface [15]. The differences in these power spectra is given by the different crystallinities of SPE, since SPE conductivity increases with the crystallization temperature [14] and the morphology of the electrode/electrolyte interface develops as SPE porosity decreases with the crystallization temperature.…”

Section: Resultsmentioning

confidence: 99%

Effect of the Different Crystallinity of Ionic Liquid Based Solid Polymer Electrolyte on the Performance of Amperometric Gas Sensor

Sedlák

Kuberský

Gajdoš

et al. 2020

7th International Electronic Conference on Sensors and Applications

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Solid polymer electrolytes (SPE) based on ionic liquid, poly-(vinylidene fluoride) and solvent N-methyl-pyrrolidone represent an effective component in electrochemical sensors. The advantage lies in their composition, which offers an opportunity to prepare SPE layers with a different porosity and microstructure. The study shows how the SPEs of different crystallinities affect the performance of an amperometric gas sensor from the point of view of current response (sensitivity), limit of detection and current fluctuations. The morphology of SPE has an impact not only on its conductivity but also on sensor sensitivity due to the morphology of the interface SPE/working electrode (WE).

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The Effect of the Orientation Towards Analyte Flow on Electrochemical Sensor Performance and Current Fluctuations

Cited by 13 publications

References 33 publications

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte

Design and Integration of a Gas Sensor Module that Indicates the End of Service Life of a Gas Mask Canister

Effect of the Different Crystallinity of Ionic Liquid Based Solid Polymer Electrolyte on the Performance of Amperometric Gas Sensor

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