A Miniaturized Amperometric Hydrogen Sulfide Sensor Applicable for Bad Breath Monitoring

Gatty, Hithesh K.; Stemme, Göran; Roxhed, Niclas

doi:10.3390/mi9120612

Cited by 12 publications

(10 citation statements)

References 15 publications

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“…Gas sensors that are used to detect hydrogen sulfide [4], carbon dioxide [5], hydrogen [6], nitrogen dioxide [7], and formaldehyde [8] have been miniaturized using microelectromechanical system (MEMS) technology. Gas microsensors that use this technology are quiet and highly sensitive, feature low power consumption, and can be mass-produced easily.…”

Section: Introductionmentioning

confidence: 99%

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

et al. 2020

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This study describes the fabrication of an ammonia gas sensor (AGS) using a complementary metal oxide semiconductor (CMOS)–microelectromechanical system (MEMS) technique. The structure of the AGS features interdigitated electrodes (IDEs) and a sensing material on a silicon substrate. The IDEs are the stacked aluminum layers that are made using the CMOS process. The sensing material; polypyrrole/reduced graphene oxide (PPy/RGO), is synthesized using the oxidation–reduction method; and the material is characterized using an electron spectroscope for chemical analysis (ESCA), a scanning electron microscope (SEM), and high-resolution X-ray diffraction (XRD). After the CMOS process; the AGS needs post-processing to etch an oxide layer and to deposit the sensing material. The resistance of the AGS changes when it is exposed to ammonia. A non-inverting amplifier circuit converts the resistance of the AGS into a voltage signal. The AGS operates at room temperature. Experiments show that the AGS response is 4.5% at a concentration of 1 ppm NH3; and it exhibits good repeatability. The lowest concentration that the AGS can detect is 0.1 ppm NH3

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Section: Introductionmentioning

confidence: 99%

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

et al. 2020

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“…H 2 S is also known to be exhaled in “bad breath” (also known as halitosis). It is considered as “normal” in the range of 80–160 ppb, “weak” in the range of 160–250 ppb, and “strong” if exhaled in concentrations greater than 250 ppb . Hence, sub-ppm detection of H 2 S can aid in disease diagnosis at an early stage.…”

Section: Introductionmentioning

confidence: 99%

“…It is considered as "normal" in the range of 80−160 ppb, "weak" in the range of 160−250 ppb, and "strong" if exhaled in concentrations greater than 250 ppb. 3 Hence, sub-ppm detection of H 2 S can aid in disease diagnosis at an early stage. Food sector is another emerging area where H 2 S can be used to access the spoilage of fruits and vegetables and adulterated milk and other dairy products.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembled Nanostructured Tin Oxide Thin Films at the Air–Water Interface for Selective H₂S Detection

Bellare

Sakhuja

Kundu

et al. 2020

ACS Appl. Nano Mater.

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Simple, inexpensive, and scalable strategies for metal oxide thin film growth are critical for potential applications in the field of gas sensing. Here, we report a general method for the synthesis of free-standing oxide thin films via a one-step, surfactant-free hydrothermal reaction wherein the oxide film forms at the air–water interface. Using SnO2 and PdO as model systems, we show that the thin films, thus formed, have lateral dimensions of the order of centimeters and thickness of the order of tens of nanometers. Transmission electron microscopy (TEM) has been used to understand the growth mechanism of the films. On the basis of these studies, we propose that the metal oxide particles formed in the bulk of the solution move to the interface and get trapped to form a continuous, polycrystalline film. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements have been performed to understand the structure, morphology, and thickness of the films. Thickness tunability by varying the precursor concentration has been explored, which in turn affects optical and gas sensing properties. Thin SnO2 films (30 nm) revealed an ultrasensitive response (R) of 25000% to 6 ppm of H2S at 150 °C while demonstrating 25 ppb (R = 19.3%) as the experimental lowest limit of detection. The selectivity of these nanostructured films toward H2S stands tall among the other interfering gases by exhibiting an ∼2 orders higher response magnitude. Furthermore, these thin films are highly stable at elevated temperatures.

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“…Papers [1,2] deal with sensing material preparation and the characterization of the chemico-physical and sensing properties, while further studies report about the investigation of sensing performance towards different operating conditions [3] and the optimization of the transduction mechanism and of the device package [4]. Furthermore, there are three papers focused on gas sensor systems and their application in environmental monitoring [5,6] and in the biomedical field [7].…”

mentioning

confidence: 99%

“…Ultimately, in the biomedical field, the design and development of mini-invasive systems for gas monitoring is a real challenge. In such a scenario, breath analysis is one of the best candidates, so Gatty et al developed and characterized an integrated amperometric sensor [7] in order to determine the hydrogen sulphide (H 2 S) concentration, one of the main reasons of malodour, in oral breath.…”

mentioning

confidence: 99%

Editorial for the Special Issue on Nanostructure Based Sensors for Gas Sensing: from Devices to Systems

Donato

Grassini

2019

Micromachines

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The development of solid state gas sensors based on microtransducers and nanostructured sensing materials is the key point in the design of new portable measurement systems with sensing and identification performances comparable with those of most sophisticated analytical techniques. In such a context, a lot of effort must be spent of course in the development of the sensing material, but also in the choice of the transducer mechanism and structure, in the electrical characterization of the sensor prototypes, as well as in the design of suitable measurement setups. [...]

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A Miniaturized Amperometric Hydrogen Sulfide Sensor Applicable for Bad Breath Monitoring

Cited by 12 publications

References 15 publications

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

Self-Assembled Nanostructured Tin Oxide Thin Films at the Air–Water Interface for Selective H₂S Detection

Editorial for the Special Issue on Nanostructure Based Sensors for Gas Sensing: from Devices to Systems

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A Miniaturized Amperometric Hydrogen Sulfide Sensor Applicable for Bad Breath Monitoring

Cited by 12 publications

References 15 publications

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

Low-Concentration Ammonia Gas Sensors Manufactured Using the CMOS–MEMS Technique

Self-Assembled Nanostructured Tin Oxide Thin Films at the Air–Water Interface for Selective H2S Detection

Editorial for the Special Issue on Nanostructure Based Sensors for Gas Sensing: from Devices to Systems

Contact Info

Product

Resources

About

Self-Assembled Nanostructured Tin Oxide Thin Films at the Air–Water Interface for Selective H₂S Detection