Electrospun Electroactive Polymer and Metal Oxide Nanofibers for Chemical Sensor Applications

2010 ◽  
Author(s):  
Jonas Flueckiger ◽  
Frank K. Ko ◽  
Karen C. Cheung
Keyword(s):  
Metal Oxide ◽  
Chemical Sensor ◽  
Response Times ◽  
Electrical Characterization ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Fast Response ◽  
Sensor Applications ◽  
Tio2 Nanofiber ◽  
Good Signal

We present the fabrication of a polymer blend PANi/PEO nanofiber based sensor as well as a metal oxide TiO2 nanofiber based sensor. Electrospinning was used for the fabrication of the electroactive nanofibers. The conductivity of those fibers is highly sensitive to the chemical environment and is modified through the adsorption of different species. Used as a chemiresistor the nanofibers offer a higher sensitivity than thin films due to the increased surface to volume ratio. Impedance spectroscopy was used for electrical characterization of the fibers showing high sensitivity. Preliminary measurements of the sensors dynamic response when exposed to alternating chemical environments showed fast response times and good signal stability.

A Self-Locking Technique With Fast Response and High Sensitivity for Micro-Cantilever Based Sensing of Analytes

2002 ◽  
Vol 723 ◽  
Author(s):  
A. Mehta ◽  
G. Muralidharan ◽  
A. Passian ◽  
S. Cherian ◽  
T.L. Ferrell ◽  
...  
Keyword(s):  
Response Times ◽  
High Sensitivity ◽  
Fast Response ◽  
Q Factor ◽  
Ambient Conditions ◽  
Sensor Applications ◽  
Feedback Scheme ◽  
Micro Cantilever ◽  
Lock In ◽  
Thermal Oscillations

AbstractMEMS based microcantilevers have been employed as sensors in both liquid and ambient conditions. One scheme for detection is based upon monitoring the change in microcantilever resonant frequency as a function of the adsorbed analyte concentration. However, the sensitivity is limited by the accuracy of the frequency measurements, which is a function of the Q-factor of the vibrating element and the measurement bandwidth. In this paper, we present a feedback scheme for self-locking amplification of the small-amplitude thermal oscillations of the microcantilever. Using this approach, we demonstrate an improvement in the Q-factor by two to three orders of magnitude as compared to that of the undriven microcantilever. Use of this technique eliminates the need for lock-in detection and results in improved response times for sensor applications. Experiments using the proposed feedback amplification technique show improved sensitivity for the detection of biological molecules in liquids, and for adsorbed vapors under ambient conditions.

scholarly journals Alcohol-based highly conductive polymer for conformal nanocoatings on hydrophobic surfaces toward a highly sensitive and stable pressure sensor

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Jung Joon Lee ◽  
Srinivas Gandla ◽  
Byeongjae Lim ◽  
Sunju Kang ◽  
Sunyoung Kim ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Mechanical Stability ◽  
Exchange Process ◽  
Conductive Polymer ◽  
High Sensitivity ◽  
Fast Response ◽  
Pdms Surface ◽  
Practical Applications ◽  
Sensor Applications ◽  
Water Based

Abstract Conformal and ultrathin coating of highly conductive PEDOT:PSS on hydrophobic uneven surfaces is essential for resistive-based pressure sensor applications. For this purpose, a water-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution was successfully exchanged to an organic solvent-based PEDOT:PSS solution without any aggregation or reduction in conductivity using the ultrafiltration method. Among various solvents, the ethanol (EtOH) solvent-exchanged PEDOT:PSS solution exhibited a contact angle of 34.67°, which is much lower than the value of 96.94° for the water-based PEDOT:PSS solution. The optimized EtOH-based PEDOT:PSS solution exhibited conformal and uniform coating, with ultrathin nanocoated films obtained on a hydrophobic pyramid polydimethylsiloxane (PDMS) surface. The fabricated pressure sensor showed high performances, such as high sensitivity (−21 kPa−1 in the low pressure regime up to 100 Pa), mechanical stability (over 10,000 cycles without any failure or cracks) and a fast response time (90 ms). Finally, the proposed pressure sensor was successfully demonstrated as a human blood pulse rate sensor and a spatial pressure sensor array for practical applications. The solvent exchange process using ultrafiltration for these applications can be utilized as a universal technique for improving the coating property (wettability) of conducting polymers as well as various other materials.

Speed of Sound Measurement in Solids Using Polyvinylidene Fluoride (PVDF) Sensors

2013 ◽  
Author(s):  
Leon M. Headings ◽  
Kunal Kotian ◽  
Marcelo J. Dapino
Keyword(s):  
Finite Element ◽  
Stress Wave ◽  
Speed Of Sound ◽  
Polyvinylidene Fluoride ◽  
Response Times ◽  
High Sensitivity ◽  
Fast Response ◽  
Load Path ◽  
Straightforward Method ◽  
The Impact

Piezoelectric film sensors such as polyvinylidene flouride (PVDF) generate an electrical voltage in response to an applied mechanical stress with a remarkably high sensitivity. They provide very fast response times and do not require extensive signal conditioning. This paper presents a straightforward method of measuring the speed of sound in solid materials and structures using commercial PVDF sensors. PVDF sensors are most commonly used to measure stresses applied in the sensors’ thickness direction. However, this requires that the sensors be located in the load path, which may result in damage to the sensor or affect the response of the system. In this paper, two PVDF sensors are bonded to the side of a structure and a small impact is applied to one end. The sensors are used to measure the time for the impact-induced plane stress wave to travel between the sensors. The observed speed of the propagating stress wave is shown to be in good agreement with the theoretical speed of sound for the material and finite element calculations. In addition, the finite element simulations confirm the validity of the plane wave assumption for non-ideal and non-uniform impact inputs.

scholarly journals Metal/Metal-Oxide Nanoclusters for Gas Sensor Applications

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Ahmad I. Ayesh
Keyword(s):  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Recent Progress ◽  
Volume Ratio ◽  
Building Blocks ◽  
Special Focus ◽  
Gaseous Species ◽  
Sensor Applications ◽  
Metal Metal

The development of gas sensors that are based on metal/metal-oxide nanoclusters has attracted intensive research interest in the last years. Nanoclusters are suitable candidates for gas sensor applications because of their large surface-to-volume ratio that can be utilized for selective and rapid detection of various gaseous species with low-power consuming electronics. Herein, nanoclusters are used as building blocks for the construction of gas sensor where the electrical conductivity of the nanoclusters changes dramatically upon exposure to the target gas. In this review, recent progress in the fabrication of size-selected metallic nanoclusters and their utilization for gas sensor applications is presented. Special focus will be given to the enhancement of the sensing performance through the rational functionalization and utilization of different nanocluster materials.

scholarly journals Wireless Wearable Electrochemical Sensors: A Review

2021 ◽  
Vol 8 (10Years) ◽  
Author(s):  
Thais Alves ◽  
Patricia Deroco ◽  
Dagwin Wachholz Junior ◽  
Lourenço Vidotto ◽  
Lauro Kubota
Keyword(s):  
Chemical Sensor ◽  
New Technologies ◽  
Electrochemical Sensors ◽  
Wearable Sensors ◽  
High Sensitivity ◽  
Fast Response ◽  
Manufacturing Cost ◽  
Time Data ◽  
Power Sources ◽  
Home Based

The demand for wearable sensors has been grown rapidly over the past few years, mainly those related to monitor health, fitness and their surroundings. Consequently, wearable chemical sensing has become a crucial appliance area for wireless sensors and has proved to be a very challenging and multidisciplinary area. The great advantage of coupling wireless communication to different types of wearable sensors is the enhancement of the sensor’s scope for remote and resource-limited settings with the possibility of obtaining real-time data acquisition and application in different areas like homeland defense, home-based healthcare, and food logistics. Being the electrochemical sensors considered attractive and promising to use in the wireless chemical sensor field, due to its features such as simple structure, the possibility of miniaturization, comfort, simplicity of operation, high sensitivity, fast response, relatively low energy consumption and low manufacturing cost. Furthermore, wearable electrochemical sensors enable obtaining insights into individuals' health status through the noninvasive monitoring of clinically relevant biomarkers in different biofluids without complex sampling, manipulation and treatment steps. In this review, we present the main advances in technologies used in the development of fully integrated wireless wearable electrochemical devices, such as communication protocols, data collection and privacy concerns and power sources. We also discuss in a critical way the main challenges, trends, strategies and new technologies that will drive this research line in the future. Lastly, we highlight the progress in the last few years in healthcare, sports, security and defense, and forensic applications.

scholarly journals Ultraviolet Photoactivated Room Temperature NO2 Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO2 Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 462 ◽  
Author(s):  
Hee-Jung Choi ◽  
Soon-Hwan Kwon ◽  
Won-Seok Lee ◽  
Kwang-Gyun Im ◽  
Tae-Hyun Kim ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Tio2 Nanoparticles ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
Prolonged Exposure ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Detection Property ◽  
No2 Gas Sensors

Prolonged exposure to NO2 can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler’s disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and surface-to-volume ratio compared to layered materials. In particular, the different morphologies of ZnO-based nanostructures significantly affect the detection property of NO2 gas sensors. However, because of the large interaction energy of chemisorption (1–10 eV), metal oxide-based gas sensors are typically operated above 100 °C, overcoming the energy limits to attain high sensitivity and fast reaction. High operating temperature negatively affects the reliability and durability of semiconductor-based sensors; at high temperature, the diffusion and sintering effects at the metal oxide grain boundaries are major factors causing undesirable long-term drift problems and preventing stability improvements. Therefore, we demonstrate NO2 gas sensors consisting of ZnO hemitubes (HTs) and nanotubes (NTs) covered with TiO2 nanoparticles (NPs). To operate the gas sensor at room temperature (RT), we measured the gas-sensing properties with ultraviolet illumination onto the active region of the gas sensor for photoactivation instead of conventional thermal activation by heating. The performance of these gas sensors was enhanced by the change of barrier potential at the ZnO/TiO2 interfaces, and their depletion layer was expanded by the NPs formation. The gas sensor based on ZnO HTs showed 1.2 times higher detection property than those consisting of ZnO NTs at the 25 ppm NO2 gas.

Study of Sensitivity of Porous Thick-Film Elements Based on SnO2 towards Hydrogen Concentration in Air

2020 ◽  
Vol 25 (6) ◽  
pp. 539-547
Author(s):  
V.V. Amelichev ◽  
◽  
S.S. Generalov ◽  
A.V. Nikolaeva ◽  
S.A. Polomoshnov ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Porous Metal ◽  
High Sensitivity ◽  
Fast Response ◽  
Gas Composition ◽  
Sensitive Layer ◽  
Initial Suspension ◽  
Semiconductor Gas Sensors ◽  
Manufacturing Technologies

The semiconductor gas sensors with low power consumption have high sensitivity and fast response and their manufacturing technologies permit to reduce the dimensions of the transducer. In production of the semiconductor gas sensors the formation of metal-oxide sensitive layer is an important issue, in particular, the process of combination of the high-porous metal-oxide layer and integrated structures. In the paper, the results of the study on experimental transducers of the composition of gas with porous gas-sensitive layer have been presented. The gas-sensitive layer has been formed by the method of suspension inkjet printing of SnO based suspension with further annealing. The comparison of the sensitivity of the experimental samples of the gas composition transducers with the gas-sensitive layers, formed from two variants of initial suspension: based on pure SnO and SnO doped with Cr and Nb, has been performed. The dependence of variation of conductivity of the gas composition of the integrated transducer specimen on the H concentration in the air has been obtained. It has been found that the gas-sensitive layer based on SnO with Cr and Nb additives has higher sensitivity to changes in the detected gas concentration due to higher effective surface area and suppressed grains agglomeration.

scholarly journals A Carbon Nanotube–Metal Oxide Hybrid Material for Visible-Blind Flexible UV-Sensor

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 368
Author(s):  
Pawan Pathak ◽  
Sanghoon Park ◽  
Hyoung Jin Cho
Keyword(s):  
Carbon Nanotube ◽  
Metal Oxide ◽  
Mechanical Stability ◽  
High Sensitivity ◽  
Fast Response ◽  
Oxide Semiconductor ◽  
Smart Devices ◽  
Wearable Electronics ◽  
Sensing Applications ◽  
Multi Walled Carbon Nanotubes

Flexible sensors with low fabrication cost, high sensitivity, and good stability are essential for the development of smart devices for wearable electronics, soft robotics, and electronic skins. Herein, we report a nanocomposite material based on carbon nanotube and metal oxide semiconductor for ultraviolet (UV) sensing applications, and its sensing behavior. The sensors were prepared by a screen-printing process under a low-temperature curing condition. The formation of a conducting string node and a sensing node could enhance a UV sensing response, which could be attributed to the uniform mixing of functionalized multi-walled carbon nanotubes and zinc oxide nanoparticles. A fabricated device has shown a fast response time of 1.2 s and a high recovery time of 0.8 s with good mechanical stability.

scholarly journals Electrically Transduced Gas Sensors Based on Semiconducting Metal Oxide Nanowires

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6781
Author(s):  
Ying Wang ◽  
Li Duan ◽  
Zhen Deng ◽  
Jianhui Liao
Keyword(s):  
Metal Oxide ◽  
Low Power ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Disease Diagnosis ◽  
Thermal Stabilities ◽  
Semiconducting Metal Oxide ◽  
Sensing Performance

Semiconducting metal oxide-based nanowires (SMO-NWs) for gas sensors have been extensively studied for their extraordinary surface-to-volume ratio, high chemical and thermal stabilities, high sensitivity, and unique electronic, photonic and mechanical properties. In addition to improving the sensor response, vast developments have recently focused on the fundamental sensing mechanism, low power consumption, as well as novel applications. Herein, this review provides a state-of-art overview of electrically transduced gas sensors based on SMO-NWs. We first discuss the advanced synthesis and assembly techniques for high-quality SMO-NWs, the detailed sensor architectures, as well as the important gas-sensing performance. Relationships between the NWs structure and gas sensing performance are established by understanding general sensitization models related to size and shape, crystal defect, doped and loaded additive, and contact parameters. Moreover, major strategies for low-power gas sensors are proposed, including integrating NWs into microhotplates, self-heating operation, and designing room-temperature gas sensors. Emerging application areas of SMO-NWs-based gas sensors in disease diagnosis, environmental engineering, safety and security, flexible and wearable technology have also been studied. In the end, some insights into new challenges and future prospects for commercialization are highlighted.

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