scholarly journals Fully Printed Flexible Chemiresistors with Tunable Selectivity Based on Gold Nanoparticles

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 116
Author(s):  
Bendix Ketelsen ◽  
Patrick P. Tjarks ◽  
Hendrik Schlicke ◽  
Ying-Chih Liao ◽  
Tobias Vossmeyer
Keyword(s):  
Gold Nanoparticles ◽  
Water Concentration ◽  
Langmuir Model ◽  
Cross Linking ◽  
First Order ◽  
Recovery Times ◽  
Printed Sensors ◽  
Response And Recovery ◽  
Dispenser Printing ◽  
Chemical Selectivity

This study presents a method for printing flexible chemiresistors comprising thin film transducers based on cross-linked gold nanoparticles (GNPs). First, interdigitated silver paste electrodes are printed onto polyimide (PI) foil via dispenser printing. Second, coatings of GNPs and dithiol/monothiol blends are inkjet-printed onto these electrode structures. 1,9-Nonanedithiol (9DT) is used as cross-linking agent and a variety of monothiols are added to tune the sensors’ chemical selectivity. When dosing these sensors with different analyte vapors (n-octane, toluene, 4-methyl-2-pentanone, 1-butanol, 1-propanol, ethanol, water; concentration range: 25–2000 ppm) they show fully reversible responses with short response and recovery times. The response isotherms follow a first-order Langmuir model, and their initial slopes reveal sensitivities of up to 4.5 × 10−5 ppm−1. Finally, it is demonstrated that arrays of printed sensors can be used to clearly discern analytes of different polarity.

scholarly journals Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 648
Author(s):  
Aijie Liang ◽  
Jingyuan Ming ◽  
Wenguo Zhu ◽  
Heyuan Guan ◽  
Xinyang Han ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Small Diameter ◽  
High Sensitivity ◽  
Large Change ◽  
Small Variation ◽  
Response Speed ◽  
Fast Response ◽  
Tin Disulfide ◽  
Recovery Times ◽  
Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

Selective Colorimetric Detection of Hydrogen Sulfide Based on Primary Amine-Active Ester Cross-Linking of Gold Nanoparticles

2015 ◽  
Vol 87 (14) ◽  
pp. 7267-7273 ◽  
Author(s):  
Zhiqin Yuan ◽  
Fengniu Lu ◽  
Meihua Peng ◽  
Chia-Wei Wang ◽  
Yu-Ting Tseng ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Hydrogen Sulfide ◽  
Primary Amine ◽  
Colorimetric Detection ◽  
Cross Linking ◽  
Active Ester

scholarly journals Capacitive type Humidity Sensor based on PANI decorated Cu-Zns Porous Micropshere

2020 ◽  
Author(s):  
Jolly Bhadra ◽  
Hemalatha Parangusan ◽  
Zubair Ahmad ◽  
Shoaib Mallick ◽  
Farid Touati ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
In Situ Polymerization ◽  
Fast Response ◽  
Polymerization Process ◽  
Average Response ◽  
Surface Absorption ◽  
Absorption Properties ◽  
Recovery Times ◽  
Response And Recovery

PANI coated Cu-ZnS porous microsphere structures have been synthesized by hydrothermal method and in-situ polymerization process. The synthesized composite is characterized by different techniques in order to study the structural, morphological and surface absorption properties. The experimental observation demonstrates that the PANI/1%Cu-ZnS composite has better sensitivity, fast response and good stability as compared to pure PANI and other PANI/CuZnS compositions. Finally, PANI/1% Cu-ZnS composite has been found to be optimized for the humidity sensors due to its well-distributed roughness, porosity and hydrophilicity. The average response and recovery times of the PANI/1% Cu-ZnS are found to be 42 s and 24 s, respectively, which outperform recent results.

scholarly journals Preparation of Powders Containing Sb, Ni, and O for the Design of a Novel CO and C3H8 Sensor

2021 ◽  
Vol 11 (20) ◽  
pp. 9536
Author(s):  
Jorge Alberto Ramírez-Ortega ◽  
José Trinidad Guillén-Bonilla ◽  
Alex Guillén-Bonilla ◽  
Verónica María Rodríguez-Betancourtt ◽  
Lorenzo Gildo-Ortiz ◽  
...  
Keyword(s):  
Response Times ◽  
High Capacity ◽  
Dynamic Tests ◽  
X Ray Diffraction ◽  
Wet Chemistry ◽  
Good Thermal Stability ◽  
Great Performance ◽  
Vis Spectroscopy ◽  
Recovery Times ◽  
Response And Recovery

In this work, powders of NiSb2O6 were synthesized using a simple and economical microwave-assisted wet chemistry method, and calcined at 700, 800, and 900 °C. It was identified through X-ray diffraction that the oxide is a nanomaterial with a trirutile-type structure and space group P42/mnm (136). UV–Vis spectroscopy measurements showed that the bandgap values were at ~3.10, ~3.14, and ~3.23 eV at 700, 800, and 900 °C, respectively. Using scanning electron microscopy (SEM), irregularly shaped polyhedral microstructures with a size of ~154.78 nm were observed on the entire material’s surface. The particle size was estimated to average ~92.30 nm at the calcination temperature of 900 °C. Sensing tests in static atmospheres containing 300 ppm of CO at 300 °C showed a maximum sensitivity of ~72.67. On the other hand, in dynamic atmospheres at different CO flows and at an operating temperature of 200 °C, changes with time in electrical resistance were recorded, showing a high response, stability, and repeatability, and good sensor efficiency during several operation cycles. The response times were ~2.77 and ~2.10 min to 150 and 200 cm3/min of CO, respectively. Dynamic tests in propane (C3H8) atmospheres revealed that the material improved its response in alternating current signals at two different frequencies (0.1 and 1 kHz). It was also observed that at 360 °C, the ability to detect propane flows increased considerably. As in the case of CO, NiSb2O6’s response in propane atmospheres showed very good thermal stability, efficiency, a high capacity to detect C3H8, and short response and recovery times at both frequencies. Considering the great performance in propane flows, a sensor prototype was developed that modulates the electrical signals at 360 °C, verifying the excellent functionality of NiSb2O6.

scholarly journals Improvement of recovered activity and stability of the Aspergillus oryzae β-galactosidase immobilized on duolite A568 by combination of immobilization methods

2017 ◽  
Vol 23 (4) ◽  
pp. 495-506 ◽  
Author(s):  
Larissa Falleiros ◽  
Bruna Cabral ◽  
Janaína Fischer ◽  
Carla Guidini ◽  
Vicelma Cardoso ◽  
...  
Keyword(s):  
Activation Energy ◽  
Aspergillus Oryzae ◽  
Physical Adsorption ◽  
Cross Linking ◽  
Thermal Deactivation ◽  
Order Model ◽  
First Order ◽  
Immobilized Biocatalyst ◽  
The Stability ◽  
Kinetics Of

The immobilization and stabilization of Aspergillus oryzae ?-galactosidase on Duolite??A568 was achieved using a combination of physical adsorption, incubation step in buffer at pH 9.0 and cross-linking with glutaraldehyde and in this sequence promoted a 44% increase in enzymatic activity as compared with the biocatalyst obtained after a two-step immobilization process (adsorption and cross-linking). The stability of the biocatalyst obtained by three-step immobilization process (adsorption, incubation in buffer at pH 9.0 and cross-linking) was higher than that obtained by two-steps (adsorption and cross-linking) and for free enzyme in relation to pH, storage and reusability. The immobilized biocatalyst was characterized with respect to thermal stability in the range 55-65 ?C. The kinetics of thermal deactivation was well described by the first-order model, which resulted in the immobilized biocatalyst activation energy of thermal deactivation of 71.03 kcal/mol and 5.48 h half-life at 55.0 ?C.

Xylene-sensing of Fe2(MoO4)3 nanoplates prepared via a hydrothermal method

2017 ◽  
Vol 10 (03) ◽  
pp. 1750022 ◽  
Author(s):  
Mengying Xu ◽  
Zhidong Lin ◽  
Wenying Guo ◽  
Yuyuan Hong ◽  
Ping Fu ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Hydrothermal Process ◽  
Optimum Operating ◽  
Average Crystalline Size ◽  
Optimum Operating Temperature ◽  
Recovery Times ◽  
Response And Recovery ◽  
Simple Hydrothermal Process

Fe2(MoO4)3 nanoplates were prepared via a simple hydrothermal process. The average crystalline size of these nanoplates is 85.8[Formula: see text]nm. The sensor based on Fe2(MoO4)3 shows a high gas sensing performance to xylene. The response of Fe2(MoO4)3 sensor is 25.9–100[Formula: see text]ppm xylene at optimum operating temperature of 340[Formula: see text]C. The response and recovery times to 100[Formula: see text]ppm xylene are 4 and 10[Formula: see text]s, respectively. Furthermore, the Fe2(MoO4)3 sensor exhibits remarkable selectivity detection of xylene gas with negligible responses to toluene and benzene. Therefore, the Fe2(MoO4)3 is a promising material for the detection of xylene gas sensors.

Fabrication of TiO2 sensor using rapid breakdown anodization method to measure pressure, humidity and sense gases at room temperature

2019 ◽  
pp. 1694-1703
Author(s):  
Reem Saadi Khaleel ◽  
Mustafa Shakir Hashim
Keyword(s):  
Room Temperature ◽  
Average Pressure ◽  
Spherical Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recovery Times ◽  
Sensitivity And Selectivity ◽  
Response And Recovery ◽  
Anodization Method ◽  
Rapid Breakdown Anodization

Rapid breakdown anodization (RBA) process was used to fabricate TiO2 sensor to measure pressure and humidity and sense gases at room temperature. This chemical process transformed Ti to its oxide (TiO2) as a powder with amorphous phase as X ray diffraction (XRD) technique confirmed.  This oxide consisted from semi spherical nanoparticles and titania nanotubes (TNTs) as Scanning electron microscope (SEM) technique showed.  TiO2 powder was deposited on Ti substrates by using electrophoretic deposition (EPD) method.   Average pressure sensitivity was 0.34 MΩ/bar and hysteresis area was 1.4 MΩ .bar. Resistance of TiO2 decreased exponentially with the increasing of relative humidity (RH%). The sensitivity% of TiO2 for RH% was greater than 70% in the range of (50-95). TiO2 was tested as a sensor for Ammonia, Ethanol and Methanol. Its sensitivity and selectivity towards Ammonia were the greatest but the shortest response and recovery times were recorded toward Methanol.

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