scholarly journals Development of Capacitive-Type Sensors by Electrochemical Anodization: Humidity and Touch Sensing Applications

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7317
Author(s):  
Joaquim O. Carneiro ◽  
Artur Ribeiro ◽  
Filipe Miranda ◽  
Iran Rocha Segundo ◽  
Salmon Landi ◽  
...  
Keyword(s):  
Pore Size ◽  
Mean Free Path ◽  
Electrochemical Anodization ◽  
Test Cases ◽  
Capacitance Change ◽  
Humidity Sensing ◽  
E Coli ◽  
Pore Blocking ◽  
Sensing Applications ◽  
First Case

This work describes the development of a capacitive-type sensor created from nanoporous anodic aluminium oxide (NP-AAO) prepared by the one-step anodization method conducted in potentiostatic mode and performed in a low-cost homemade system. A series of samples were prepared via an anodization campaign carried out on different acid electrolytes, in which the anodization parameters were adjusted to investigate the effect of pore size and porosity on the capacitive sensing performance. Two sensor test cases are investigated. The first case explores the use of highly uniform NP-AAO structures for humidity sensing applications while the second analyses the use of NP-AAO as a capacitive touch sensor for biological applications, namely, to detect the presence of small “objects” such as bacterial colonies of Escherichia Coli. A mathematical model based on equivalent electrical circuits was developed to evaluate the effect of humidity condensation (inside the pores) on the sensor capacitance and also to estimate the capacitance change of the sensor due to pore blocking by the presence of a certain number of bacterial microorganisms. Regarding the humidity sensing test cases, it was found that the sensitivity of the sensor fabricated in a phosphoric acid solution reaches up to 39 (pF/RH%), which is almost three times higher than the sensor fabricated in oxalic acid and about eight times higher than the sensor fabricated in sulfuric acid. Its improved sensitivity is explained in terms of the pore size effect on the mean free path and the loss of Brownian energy of the water vapour molecules. Concerning the touch sensing test case, it is demonstrated that the NP-AAO structures can be used as capacitive touch sensors because the magnitude of the capacitance change directly depends on the number of bacteria that cover the nanopores; the fraction of the electrode area activated by bacterial pore blocking is about 4.4% and 30.2% for B1 (E. Coli OD600nm = 0.1) and B2 (E. Coli OD600nm = 1) sensors, respectively.

scholarly journals Wide range and highly linear signal processed systematic humidity sensor array using Methylene Blue and Graphene composite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Umair Khan ◽  
Gul Hassan ◽  
Rayyan Ali Shaukat ◽  
Qazi Muhammad Saqib ◽  
Mahesh Y. Chougale ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Linear Combination ◽  
Linear Function ◽  
Humidity Sensor ◽  
Sensor Array ◽  
Combination Method ◽  
Humidity Sensing ◽  
Sensing Applications ◽  
Wide Range ◽  
Graphene Flakes

AbstractThis paper proposes a signal processed systematic 3 × 3 humidity sensor array with all range and highly linear humidity response based on different particles size composite inks and different interspaces of interdigital electrodes (IDEs). The fabricated sensors are patterned through a commercial inkjet printer and the composite of Methylene Blue and Graphene with three different particle sizes of bulk Graphene Flakes (BGF), Graphene Flakes (GF), and Graphene Quantum Dots (GQD), which are employed as an active layer using spin coating technique on three types of IDEs with different interspaces of 300, 200, and 100 µm. All range linear function (0–100% RH) is achieved by applying the linear combination method of nine sensors in the signal processing field, where weights for linear combination are required, which are estimated by the least square solution. The humidity sensing array shows a fast response time (Tres) of 0.2 s and recovery time (Trec) of 0.4 s. From the results, the proposed humidity sensor array opens a new gateway for a wide range of humidity sensing applications with a linear function.

Real Gas Effect on Gas Slippage Phenomenon in Shale

2021 ◽  
Author(s):  
Yufei Chen ◽  
Juliana Y. Leung ◽  
Changbao Jiang ◽  
Andrew K. Wojtanowicz
Keyword(s):  
Pore Size ◽  
Free Path ◽  
Mean Free Path ◽  
Real Gas ◽  
The Real ◽  
Gas Slippage ◽  
Real Gas Effect ◽  
Shale Reservoirs ◽  
Low Pressures ◽  
Gas Effect

Abstract The past decade has seen the rapid development of shale gas across the world, as the record-breaking success and on-going surge of commercial shale gas production in such unconventional reservoirs pose a tremendous potential to meet the global energy supply. However, questions have been raised about the intricate gas transport mechanisms in the shale matrix, of which the gas slippage phenomenon is one of the key mechanisms for enhancing the fluid transport capacity and, therefore, the overall gas production. Given that shale reservoirs are often naturally deposited in the deep underground formations at high pressure and temperature conditions (much deeper than most typical conventional deposits), the real gas effect cannot be ignored as gas properties may vary significantly under such conditions. The purpose of this study is thus to investigate the real gas effect on the gas slippage phenomenon in shale by taking into account the gas compressibility factor (Z) and Knudsen number (Kn). This study begins with a specific determination of Z for natural gas at various pressures and temperatures under the real gas effect, followed by several calculations of the gas molecular mean free path at in-situ conditions. Following this, the real gas effect on gas slippage phenomenon in shale is specifically analyzed by examining the change in Knudsen number. Also discussed are the permeability deviation from Darcy flux (non-Darcy flow) due to the combination of gas slippage and real gas effect and the specific range of pressure and pore size for gas slippage phenomenon in shale reservoirs. The results show that the gas molecular mean free path generally increases with decreasing pressure, especially at relatively low pressures (< 20 MPa). And, increasing temperature will cause the gas molecular mean free path to rise, also at low pressures. Knudsen number of an ideal gas is greater than that of a real gas; while lower than that of a real gas as pressure continues to rise. That is, the real gas effect suppresses the gas slippage phenomenon at low pressures, while enhancing it at high pressures. Also, Darcy’s law starts deviating when Kn > 0.01 and becomes invalid at high Knudsen numbers, and this deviation increases with decreasing pore size. No matter how pore size varies, this deviation increases with decreasing pressure, meaning that the gas slippage effect is significant at low pressures. Finally, slip flow dominates in the various gas transport mechanisms given the typical range of pressure and pore size in shale reservoirs (1 MPa < P < 80 MPa; 3 nm < d < 3000 nm). Gas transport in shale is predominantly controlled by the slippage effect that mostly occurs in micro- or meso-pores (10 to 200 nm). Moreover, considering the real gas effect would improve the accuracy for determining the specific pressure range of the gas slippage phenomenon in shale.

scholarly journals Gas Sensing Properties of Mg-Incorporated Metal–Organic Frameworks

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3323 ◽  
Author(s):  
Jae-Hyoung Lee ◽  
Thanh-Binh Nguyen ◽  
Duy-Khoi Nguyen ◽  
Jae-Hun Kim ◽  
Jin-Young Kim ◽  
...  
Keyword(s):  
Pore Size ◽  
Gas Sensors ◽  
Gas Sensing ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
Kinetic Properties ◽  
Sensing Properties ◽  
Sensing Applications ◽  
Gas Sensing Properties ◽  
Metal Organic

The gas sensing properties of two novel series of Mg-incorporated metal–organic frameworks (MOFs), termed Mg-MOFs-I and -II, were assessed. The synthesized iso-reticular type Mg-MOFs exhibited good crystallinity, high thermal stability, needle-shape morphology and high surface area (up to 2900 m2·g−1), which are promising for gas sensing applications. Gas-sensing studies of gas sensors fabricated from Mg-MOFs-II revealed better sensing performance, in terms of the sensor dynamics and sensor response, at an optimal operating temperature of 200 °C. The MOF gas sensor with a larger pore size and volume showed shorter response and recovery times, demonstrating the importance of the pore size and volume on the kinetic properties of MOF-based gas sensors. The gas-sensing results obtained in this study highlight the potential of Mg-MOFs gas sensors for the practical monitoring of toxic gases in a range of environments.

A miniaturized evanescent mode HMSIW humidity sensor

2017 ◽  
Vol 10 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Chang-Ming Chen ◽  
Jun Xu
Keyword(s):  
Humidity Sensor ◽  
Split Ring Resonator ◽  
Evanescent Mode ◽  
Split Ring ◽  
Promising Candidate ◽  
Humidity Sensing ◽  
Complementary Split Ring Resonator ◽  
Sensing Applications ◽  
Sensing Material ◽  
Compact Size

A passive evanescent mode half-mode substrate integrated waveguide (HMSIW) resonator loaded with a complementary split ring resonator (CSRR) is designed and fabricated for humidity sensing applications. The use of the CSRR which is etched on the top plane of the HMSIW can significantly reduce the size of the device. Without any sensing material, the sensor which has a compact size of 0.17λg × 0.17λg can provide high humidity sensitivity up to 5.82 MHz/%relative humidity (RH) at high RH region (>84.3%). The results indicate that the proposed structure is a promising candidate for radio and microwave humidity sensing applications.

An intrinsically stretchable humidity sensor based on anti-drying, self-healing and transparent organohydrogels

2019 ◽  
Vol 6 (3) ◽  
pp. 595-603 ◽  
Author(s):  
Jin Wu ◽  
Zixuan Wu ◽  
Huihua Xu ◽  
Qian Wu ◽  
Chuan Liu ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Self Healing ◽  
Solvent Exchange ◽  
Humidity Sensing ◽  
Sensing Applications

A facile solvent-exchange strategy is devised to fabricate anti-drying, self-healing and transparent organohydrogels for stretchable humidity sensing applications.

scholarly journals Mastitis Acuta in a Pure Breed Cane Corso female. A Case Report

2017 ◽  
Vol 74 (1) ◽  
pp. 30
Author(s):  
Iosif VASIU ◽  
Raul Alexandru POP ◽  
Flore CHIRILA ◽  
Flaviu TABARAN ◽  
Marian TAULESCU ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Ph Value ◽  
Canis Lupus Familiaris ◽  
Highly Pathogenic ◽  
E Coli ◽  
Pure Breed ◽  
Neonatal Septicaemia ◽  
First Case ◽  
Life Threatening ◽  
Female Laboratory

Data regarding bitch mastitis is fairly scarce compared to the literature regarding ruminant mastitis. Neglecting clinical and subclinical cases of mastitis can be life threatening for both dam and puppies. The aim of this report is to present a case of Mastitis acuta complicated with a case of neonatal septicaemia in a Cane Corso (Canis lupus familiaris L.) pure breed female. Laboratory assays showed a milk pH value of 7.5, milk cytology revealed the presence of segmented neutrophils, while foamy cells, phagocytosis and highly pathogenic bacteria (i.e. Escherichia coli and Pseudomonas aeruginosa) were isolated from milk and puppy. To the author's knowledge, this is the first case of bitch mastitis linked to neonatal septicaemia with mixed E. coli and P. aeruginosa infection.

Highly Transparent Wafer-Scale Synthesis of Crystalline WS2 Nanoparticle Thin Film for Photodetector and Humidity-Sensing Applications

2016 ◽  
Vol 8 (5) ◽  
pp. 3359-3365 ◽  
Author(s):  
Amit S. Pawbake ◽  
Ravindra G. Waykar ◽  
Dattatray J. Late ◽  
Sandesh R. Jadkar
Keyword(s):  
Thin Film ◽  
Humidity Sensing ◽  
Wafer Scale ◽  
Sensing Applications

Positron Lifetime Spectroscopy on Controlled Pore Glass Porosimetry and Pore Size Distribution

2008 ◽  
Vol 607 ◽  
pp. 169-172 ◽  
Author(s):  
Stefan Thränert ◽  
D. Enke ◽  
G. Dlubek ◽  
Reinhard Krause-Rehberg
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mean Free Path ◽  
Infinite Length ◽  
Positron Annihilation Lifetime ◽  
Controlled Pore Glass ◽  
Pore Glass ◽  
Positron Lifetime Spectroscopy ◽  
Overlap Parameter

Positron annihilation lifetime spectroscopy (PALS) is used to study a series of controlled pore glasses (CPG). The lifetime spectra were decomposed into four components using the routine LifeTime, version 9.0 (LT9). The largest lifetime τ4, which is attributed to the annihilation of ortho-positronium (o-Ps) localized at mesopores, varied at 300 K between 21 and 131 ns. The size of mesopores (mean free path), D, was determined by N2 adsorption and Hg intrusion techniques to vary between 1.8 and 56 nm. It is shown that the Tao-Eldrup model extended to cylinders of infinite length and diameter d = D describes well the experiment for an overlap parameter δ fitted to be δ = 0.193 nm. The spectra were also analyzed allowing a distribution of o-Ps lifetimes. A method is developed to calculate the pore size distribution n(d) from the τ4 distribution. This method is of particular interest since PALS is very sensitive to pores being too small to be exactly analyzed by conventional porosimetry.

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