scholarly journals Characterization and Comparison of Biodegradable Printed Capacitive Humidity Sensors

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6557
Author(s):  
Emma Wawrzynek ◽  
Carol Baumbauer ◽  
Ana Claudia Arias
Keyword(s):  
Relative Humidity ◽  
Potato Starch ◽  
Thermal Drift ◽  
Humidity Sensors ◽  
Interdigitated Electrode ◽  
Recovery Times ◽  
Environmental Relative Humidity ◽  
Response And Recovery ◽  
Silver Electrodes ◽  
The Relationship

Flexible and biodegradable sensors are advantageous for their versatility in a range of areas from smart packaging to agriculture. In this work, we characterize and compare the performance of interdigitated electrode (IDE) humidity sensors printed on different biodegradable substrates. In these IDE capacitive devices, the substrate acts as the sensing layer. The dielectric constant of the substrate increases as the material absorbs water from the atmosphere. Consequently, the capacitance across the electrodes is a function of environmental relative humidity. Here, the performance of polylactide (PLA), glossy paper, and potato starch as a sensing layer is compared to that of nonbiodegradable polyethylene terephthalate (PET). The capacitance across inkjet-printed silver electrodes is measured in environmental conditions ranging from 15 to 90% relative humidity. The sensitivity, response time, hysteresis, and temperature dependency are compared for the sensors. The relationship between humidity and capacitance across the sensors can be modeled by exponential growth with an R2 value of 0.99, with paper and starch sensors having the highest overall sensitivity. The PET and PLA sensors have response and recovery times under 5 min and limited hysteresis. However, the paper and starch sensors have response and recovery times closer to 20 min, with significant hysteresis around 100%. The PET and starch sensors are temperature independent, while the PLA and paper sensors display thermal drift that increases with temperature.

Silicon Carbide Field Effect Transistors for Detection of Ultra-Low Concentrations of Hazardous Volatile Organic Compounds

2014 ◽  
Vol 778-780 ◽  
pp. 1067-1070 ◽  
Author(s):  
Donatella Puglisi ◽  
Jens Eriksson ◽  
Christian Bur ◽  
Andreas Schütze ◽  
Anita Lloyd Spetz ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Volatile Organic Compounds ◽  
Relative Humidity ◽  
Organic Compounds ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Long Term Stability ◽  
Volatile Organic ◽  
Recovery Times ◽  
Response And Recovery

Gas sensitive silicon carbide field effect transistors with nanostructured Ir gate layers have been used for the first time for sensitive detection of volatile organic compounds (VOCs) at part per billion level for indoor air quality applications. Formaldehyde, naphthalene, and benzene have been used as typical VOCs in dry air and under 10% and 20% relative humidity. A single VOC was used at a time to study long-term stability, repeatability, temperature dependence, effect of relative humidity, sensitivity, response and recovery times of the sensors.

scholarly journals Development of La3+Doped CeO2Thick Film Humidity Sensors

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chunjie Wang ◽  
Aihua Zhang ◽  
Hamid Reza Karimi
Keyword(s):  
Relative Humidity ◽  
High Performance ◽  
Humidity Sensor ◽  
Humidity Sensors ◽  
Response Recovery ◽  
Relative Humidity Range ◽  
Response And Recovery ◽  
Sensitive Characteristics ◽  
Humidity Range ◽  
Maximum Humidity

The humidity sensitive characteristics of the sensor fabricated from 10 mol% La2O3doped CeO2nanopowders with particle size 17.26 nm synthesized via hydrothermal method were investigated at different frequencies. It was found that the sensor shows high humidity sensitivity, rapid response-recovery characteristics, and narrow hysteresis loop at 100 Hz in the relative humidity range from 11% to 95%. The impedance of the sensor decreases by about five orders of magnitude as relative humidity increases. The maximum humidity hysteresis is about 6% RH, and the response and recovery time is 12 and 13 s, respectively. These results indicate that the nanosized La2O3doped CeO2powder has potential application as high-performance humidity sensor.

scholarly journals Response and Recovery Times of Elastic and Viscoelastic Capsules in Shear Flow

2015 ◽  
Vol 17 (5) ◽  
pp. 1151-1168 ◽  
Author(s):  
John Gounley ◽  
Yan Peng
Keyword(s):  
Shear Flow ◽  
Fluid Viscosity ◽  
Membrane Viscosity ◽  
Recovery Times ◽  
Shear Elasticity ◽  
Response And Recovery ◽  
Membrane Bending ◽  
The Relationship ◽  
Spherical Capsule

AbstractAmid the recent interest in the role of membrane viscosity in the deformation of a fluid-filled capsule, we consider the role of various capsule properties (shear elasticity, membrane bending stiffness and viscosity) in determining the response and recovery times of a spherical capsule in shear flow. These times are determined by fitting exponential functions to results for the Taylor deformation parameter Dxy. We focus on the relationship between the membrane and fluid viscosity ratios, as suggested by Diaz et al, and whether adjustments to the fluid viscosity ratio may be used to approximate the effects of membrane viscosity. Based on its ability to reproduce response and recovery times, our results suggest that such an approach holds promise.

scholarly journals Novel humidity sensors based on nanomodified Portland cement

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thanyarat Buasiri ◽  
Karin Habermehl-Cwirzen ◽  
Lukasz Krzeminski ◽  
Andrzej Cwirzen
Keyword(s):  
Electrical Resistivity ◽  
Relative Humidity ◽  
Portland Cement ◽  
Threshold Value ◽  
High Humidity ◽  
Humidity Sensors ◽  
The Relationship ◽  
Humidity Range ◽  
Very High

AbstractCommonly used humidity sensors are based on metal oxides, polymers or carbon. Their sensing accuracy often deteriorates with time, especially when exposed to higher temperatures or very high humidity. An alternative solution based on the utilization of Portland cement-based mortars containing in-situ grown carbon nanofibers (CNFs) was evaluated in this study. The relationship between the electrical resistivity, CNF content and humidity were determined. The highest sensitivity was observed for samples containing 10 wt.% of the nanomodified cement which corresponded to 0.27 wt.% of CNFs. The highest calculated sensitivity was approximately 0.01024 per 1% change in relative humidity (RH). The measured electrical resistivity is a linear function of the RH in the humidity range between 11 and 97%. The percolation threshold value was estimated to be at around 7 wt.% of the nanomodified cement, corresponding to ~ 0.19 wt.% of CNFs.

scholarly journals Waste Coffee Ground Biochar: A Material for Humidity Sensors

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 801 ◽  
Author(s):  
Pravin Jagdale ◽  
Daniele Ziegler ◽  
Massimo Rovere ◽  
Jean Tulliani ◽  
Alberto Tagliaferro
Keyword(s):  
Relative Humidity ◽  
Photoelectron Spectroscopy ◽  
Polyvinyl Butyral ◽  
Humidity Sensors ◽  
X Ray ◽  
Sensing Material ◽  
Coffee Grounds ◽  
Coffee Ground ◽  
Recovery Times ◽  
Screen Printed

Worldwide consumption of coffee exceeds 11 billion tons/year. Used coffee grounds end up as landfill. However, the unique structural properties of its porous surface make coffee grounds popular for the adsorption of gaseous molecules. In the present work, we demonstrate the use of coffee grounds as a potential and cheap source for biochar carbon. The produced coffee ground biochar (CGB) was investigated as a sensing material for developing humidity sensors. CGB was fully characterized by using laser granulometry, X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and the Brunnauer Emmett Teller (BET) technique in order to acquire a complete understanding of its structural and surface properties and composition. Subsequently humidity sensors were screen printed using an ink-containing CGB with polyvinyl butyral (PVB) acting as a temporary binder and ethylene glycol monobutyral ether, Emflow, as an organic vehicle so that the proper rheological characteristics were achieved. Screen-printed films were the heated at 300 °C in air. Humidity tests were performed under a flow of 1.7 L/min in the relative humidity range 0–100% at room temperature. The initial impedance of the film was 25.2 ± 0.15 MΩ which changes to 12.3 MΩ under 98% humidity exposure. A sensor response was observed above 20% relative humidity (RH). Both the response and recovery times were reasonably fast (less than 2 min).

Effects of graphene layer and gold nanoparticles on sensitivity of humidity sensors

2020 ◽  
Vol 3 (1) ◽  
pp. 20-27
Author(s):  
Jiawei Bao ◽  
Niloofar Hashemi ◽  
Jingshuai Guo ◽  
Nicole N. Hashemi
Keyword(s):  
Gold Nanoparticles ◽  
Relative Humidity ◽  
Graphene Layer ◽  
Humidity Sensor ◽  
Response Times ◽  
Humidity Sensors ◽  
Micro Electro Mechanical Systems ◽  
Layer Graphene ◽  
Different Response ◽  
The Relationship

Humidity sensors can be used to monitor body sweat. Here, we studied a humidity sensor that comprised of a graphene layer between two electrodes. The operating principle is that the humidity sensor will respond when vapor reaches the graphene layer from the top. Based on the humidity diffusion, the sensor measures the relative humidity (RH) with different response times. Graphene is a material with high diffusivity and small thickness that can increase the sensitivity of a sensor. Based on the micro electro mechanical systems (MEMS) method, we modeled the humidity sensor using COMSOL Multiphysics® transport of diluted species software. Additionally, we used the concentration values from the simulations to determine the relationship between capacitance and relative humidity. The sensitivity was found to be 3.379 × 10−11 pF/%RH for the 4-layer graphene, 1.210 × 10−14 pF/%RH for the 8-layer graphene, and 3.597 × 10−11 pF/%RH for the 16-layer graphene sensor. The sensitivity of 4-layer graphene with gold sensor is 3.872 × 10−13 pF/%RH which is smaller than 4-layer graphene sensor, and graphene with gold nanoparticles shows better response time than 4-layer graphene sensor.

THE SENSING OF HUMIDITY BY SURFACE-TYPE Ag/FORMYL-TIPPCu(II)/Ag SENSOR FOR ENVIRONMENTAL MONITORING

2014 ◽  
Vol 21 (04) ◽  
pp. 1450048 ◽  
Author(s):  
DIL NAWAZ KHAN ◽  
MUHAMMAD HASSAN SAYYAD ◽  
MUHAMMAD TAHIR ◽  
FAZAL WAHAB ◽  
MUHAMMAD YASEEN ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Evaporation Process ◽  
Electrical Parameters ◽  
Humidity Sensors ◽  
Surface Type ◽  
Glass Substrates ◽  
Thermal Evaporator ◽  
Silver Electrodes ◽  
Hysteresis Response ◽  
Sublimation Technique

In this paper, we have studied the effects of changing relative humidity on the electrical parameters and their multi frequency response of the surface type Ag /formyl- TIPPCu ( II )/ Ag humidity sensors. The silver electrodes of thickness 100 nm were primarily deposited on cleaned glass substrates by thermal evaporator. A gap of 40 μm was created between the electrodes of each device by using mask during the evaporation process. Thin films of formyl- TIPPCu ( II ) of 140 nm thickness were grown on silver electrodes by thermal sublimation technique. The values of capacitance and resistance of the sensors were found at different humidity levels at frequency of 1, 10 and 100 kHz of AC input signal. A remarkable increase in capacitance and decrease in resistance were observed during the rise of relative humidity from 45% to 95% RH. The hysteresis response of these humidity sensors was also studied at 1 kHz AC signal.

scholarly journals Conducting Polymer-Based Cantilever Sensors for Detection Humidity

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Clarice Steffens ◽  
Alexandra Nava Brezolin ◽  
Juliana Steffens
Keyword(s):  
Relative Humidity ◽  
Mechanical Response ◽  
Sensitive Layer ◽  
Cantilever Sensors ◽  
Cantilever Sensor ◽  
Silicon Cantilever ◽  
Recovery Times ◽  
Long Time ◽  
Response And Recovery ◽  
Low Humidity

This paper describes the use of different conducting polymers (polyaniline, poly(o-ethoxyaniline), and polypyrrole) as a sensitive layer on a silicon cantilever sensor. The mechanical response (deflection) of the bimaterial (the coated cantilever) was investigated under the influence of relative humidity. The variations in the deflection of the coated cantilevers when exposed to relative humidity were evaluated. The results indicated a linear sensitivity in ranges, where the high value was obtained for a polypyrrole-sensitive layer between 20 and 45% of humidity. Furthermore, the sensor shows excellent performance along with rapid response and recovery times, relatively low hysteresis, and excellent stability. The sensors developed are potentially excellent materials for sensing low humidity for long time.

EL NINO RELATED CLIMATE AND DENGUE FEVER CASES IN JEDDAH, SAUDI ARABIA

2019 ◽  
Vol 25 (1) ◽  
Author(s):  
MASROOR ALI KHAN ◽  
KHALID AL GHAMDI ◽  
JAZEM A. MEHYOUB ◽  
RAKHSHAN KHAN
Keyword(s):  
Relative Humidity ◽  
Dengue Fever ◽  
El Niño ◽  
Significant Relationship ◽  
El Nino ◽  
Climate Data ◽  
Light Traps ◽  
Mosquito Abundance ◽  
Dengue Transmission ◽  
The Relationship

The focus of this study is to find the relationship between El Nino and dengue fever cases in the study area.Mosquito density was recorded with the help of light traps and through aspirators collection. Climate data were obtained from National Meteorology and Environment centre. (Year wise El Nino and La Nina data are according to NOAA & Golden Gate Weather Services). Statistical methods were used to establish the correlation coefficient between different factors. A high significant relationship was observed between Relative Humidity and Dengue fever cases, but Aedes abundance had no significant relationship with either Relative humidity and Temperature. Our conclusion is that the El Nino does not affect the dengue transmission and Aedes mosquito abundance in this region, which is supported by earlier works.

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