Dynamic behavior of a chemical sensor for humidity level measurement in human breath

Tetelin, Angélique; Pouget, Vincent; Lachaud, Jean-Luc; Pellet, Claude

doi:10.1109/tim.2004.830769

Cited by 41 publications

(27 citation statements)

References 5 publications

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“…The solution was initially hydrolyzed for nearly 1 h with continuous stirring on a magnetic hot plate stirrer at a constant temperature of 90 • C. The solution was then peptized by adding concentrated hydrochloric (HCl) acid drop wise with the molar ratio~0.07 mol/mol. During peptization, the hydroxide molecules are positively charged (Al(OH) 3 + ) and are dispersed uniformly in the colloidal solution. The dispersed ions form a net structure and after complete peptization, the sol becomes transparent.…”

Section: Preparation Of the Sol For The Al 2 O 3 Sensing Filmmentioning

confidence: 99%

Sensitivity Enhancement of a PPM Level Capacitive Moisture Sensor

2017

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Abstract:Measurement of moisture at ppm or ppb level is very difficult and the fabrication of such sensors at low cost is always challenging. High sensitivity is an important parameter for trace level (ppm) humidity sensors. Anelectronic detection circuit for interfacing the humidity sensor with high sensitivity requires a simple hardware circuit with few active devices. The recent trends for increasing the sensitivity include fabricating nanoporous film with a very large surface area. In the present work, the sensitivity of a parallel plate capacitive type sensor with metal oxide sensing film has been significantly improved with an aim to detect moisture from 3 to 100 ppm in the industrial process gases used to fabricate semiconductors and other sensitive electronic devices. The sensitivity has been increased by (i) fabricating a nanoporous film of aluminum oxide using the sol-gel method and (ii) increasing the cross-sectional area of a parallel plate capacitor. A novel double sided capacitive structure has been proposed where two capacitors have been fabricated-one on the top and one on the bottom side of a flat alumina substrate-and then the capacitors are connected in parallel. The structure has twice the sensitivity of a single sensor in the same ppm range but the size of the structure remains unchanged. The important characteristics of the sensors such as the sensitivity (S = ∆C ∆ppm × 100), the response time (t r ), and the recovery time (t c ) are determined and compared with a commercial SHAW, UKdew point meter. The fabricated double sided sensor has comparable sensitivity (S = 100%, t r (s) = 28, t c (s) = 40) with the commercial meter (S = 100.5%, t r (s) = 258) but has a faster response time. The proposed method of sensitivity enhancement is simple, and mass producible.

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Section: Preparation Of the Sol For The Al 2 O 3 Sensing Filmmentioning

confidence: 99%

Sensitivity Enhancement of a PPM Level Capacitive Moisture Sensor

2017

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“…Moreover, a change of the users' sleeping position will also affect the detection results. Other types of nonvisual devices, such as temperature sensors [10], ultrasound sensors [11], humidity sensors [12] and Ultrasonic Proximity Sensor [13], are easily affected by unstable signals caused by slight environmental changes.…”

Section: Introductionmentioning

confidence: 99%

A Vision-Based Infant Respiratory Frequency Detection System

Fang

Hsieh²,

Chen

2015

2015 International Conference on Digital Image Computing: Techniques and Applications (DICTA)

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Sudden infant death syndrome (SIDS) is the major cause of death for infants aged one week to twelve months. The SIDS rate has declined owing to the awareness of caregivers and parents, but the rate is still high even in developed countries because of the difficulty in rescuing the infant immediately. Respiration, which can reflect various physiological conditions, is a basic but vital function for infants. Therefore, this study presents a respiration monitoring system with a video camera positioned in front of an infant to non-invasively detect the infant's respiratory frequency. The proposed system can continuously monitor the infant to detect unusual occurrences in the infant's respiration, to alert caregivers to attend to the infant immediately and reduce potential injuries from SIDS and other respiratory-related disease.The proposed system contains four major stages, including motion detection, candidate point extraction, respiration point selection, and respiratory frequency calculation. During motion detection the system captures images from video and decides whether to conduct the following stages. If no obvious motion is detected in the input frames, then SIDS may have occurred in the infant, and the system extracts candidate points by some spatial characteristics. Based on these points, the system then selects respiration points using a fuzzy integral technique with four temporal characteristics, including entropy, period, skewness, and kurtosis. Finally, the infant's respiratory frequency is calculated. Experimental data are obtained from ten infants, in 48 sequences with a total length of 150 minutes. The experimental results show that the proposed system is robust and efficient.Keywords-Home healthcare, vision-based infant monitoring system, vision-based infant respiratory frequency detection system, fuzzy integral.

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“…7 Tetelin et al proposed a polyimide RH sensor based on parallel plate capacitance that achieved a 1.1 second response time for use in diagnosing pulmonary deficiencies. 8 Sen and Darabi proposed a polyimide based RH sensor that employs both interdigitated electrode and parallel plate geometries to improve sensor performance by 18% over traditional parallel plate sensors for use in HVAC applications. 9 Kim et al determined that thicker polymer layers were important for capturing the effect of fringing electric field lines in interdigitated electrode sensors, and proposed a sensor with both a thicker polymer layer and an etched cavity between the electrodes which had sensitivities of 37.1 f F/%RH 10 .…”

Section: Introductionmentioning

confidence: 99%

Gelatin as a new humidity sensing material: Characterization and limitations

2014

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The goal of this work is to assert the utility of collagen and its denatured counterpart gelatin as cost-effective alternatives to existing sensing layers comprised of polymers. Rather than producing a material that will need to be discarded or recycled, collagen, as a by-product of the meat and leather industry, could be repurposed. This work examines the feasibility of using collagen as a sensing layer. Planar electrodes were patterned with lift-off process to work with the natural characteristics of gelatin by utilizing metal vapor deposition, spin coating, and photolithography. Characterization methods have also been optimized through the creation of specialized humidity chambers that isolate specific characteristics such as response time, accuracy, and hysteresis. Collagen-based sensors are found to have a sensitivity to moisture in the range of 0.065 pF/%RH. Diffusion characteristics were also analyzed with the diffusion coefficient found to be 2.5 × 10−5 cm2/s. Absorption and desorption times were found to be 20 seconds and 8 seconds, respectively. Hysteresis present in the data is attributed to temperature cross-sensitivity. Ultimately, the utility of collagen as a dielectric sensing material is, in part, due to its fibrous macrostructures as well its hydrophilic sites along the peptide chains. Gelatin was patterned between and below interdigitated copper electrodes and tested as a relative humidity sensor. This work shows that gelatin, which is inexpensive, widely available, and easy to process, can be an effective dielectric sensing polymer for capacitive-type relative humidity sensors.

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Dynamic behavior of a chemical sensor for humidity level measurement in human breath

Cited by 41 publications

References 5 publications

Sensitivity Enhancement of a PPM Level Capacitive Moisture Sensor

Sensitivity Enhancement of a PPM Level Capacitive Moisture Sensor

A Vision-Based Infant Respiratory Frequency Detection System

Gelatin as a new humidity sensing material: Characterization and limitations

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