The Experts below are selected from a list of 22050 Experts worldwide ranked by ideXlab platform
Cesar A. Barbero - One of the best experts on this subject based on the ideXlab platform.
-
Pressure and microwave sensors/actuators based on smart hydrogel/Conductive Polymer nanocomposite
Sensors and Actuators B: Chemical, 2014Co-Authors: Rebeca E. Rivero, María A. Molina, Claudia R. Rivarola, Cesar A. BarberoAbstract:A nanocomposite is fabricated by formation of a Conductive Polymer, using in situ oxidative Polymerization, inside a thermosensitive crosslinked hydrogel. FE-SEM micrographs show the nanometric domains of the Conductive material (polyaniline, PANI) dispersed in the hydrogel matrix based on cross linked poly(N-isopropylacrylamide) (PNIPAm). The thermosensitive properties of PNIPAm and coPolymers with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) are not affected by the presence of Conductive Polymer nanoparticles. The incorporation of PANI improves the mechanical properties of the hydrogel allowing it to swell up to 30,000% without breaking. Since the Conductive Polymer absorbs strongly microwave radiation at pH < 4 and heats up, the nanocomposite containing PANI suffer phase transition upon microwave irradiation. At pH > 4, PANI is not Conductive and the nanocomposite becomes insensitive to microwaves. However, using a pH insensitive Conductive Polymer (polypyrrole, PPy) in the nanocomposite makes it sensitive to microwaves at all pH values. The nanocomposite is used in a chemomechanical actuator where drug release is driven remotely by microwave irradiation. Since the PNIPAm-co-2%AMPS/PANI nanocomposite is soft and electronically Conductive, could be used as pressure/force sensor. It is shown that a compressive force applied on a cylinder of that nanocomposite increases the conductivity of material. Additionally a switch is built which turns off upon microwave irradiation. Therefore, the nanocomposites are potential candidates for different technological applications, such as: a force/pressure electrical sensor, a drug delivery device driven remotely by microwaves, pH or temperature electrical switches and an electric switch driven by microwaves. © 2013 Elsevier B.V.
-
pressure and microwave sensors actuators based on smart hydrogel Conductive Polymer nanocomposite
Sensors and Actuators B-chemical, 2014Co-Authors: Rebeca Rivero, Claudia R. Rivarola, Maria Molina, Cesar A. BarberoAbstract:Abstract A nanocomposite is fabricated by formation of a Conductive Polymer, using in situ oxidative Polymerization, inside a thermosensitive crosslinked hydrogel. FE-SEM micrographs show the nanometric domains of the Conductive material (polyaniline, PANI) dispersed in the hydrogel matrix based on cross linked poly(N-isopropylacrylamide) (PNIPAm). The thermosensitive properties of PNIPAm and coPolymers with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) are not affected by the presence of Conductive Polymer nanoparticles. The incorporation of PANI improves the mechanical properties of the hydrogel allowing it to swell up to 30,000% without breaking. Since the Conductive Polymer absorbs strongly microwave radiation at pH 4, PANI is not Conductive and the nanocomposite becomes insensitive to microwaves. However, using a pH insensitive Conductive Polymer (polypyrrole, PPy) in the nanocomposite makes it sensitive to microwaves at all pH values. The nanocomposite is used in a chemomechanical actuator where drug release is driven remotely by microwave irradiation. Since the PNIPAm-co-2%AMPS/PANI nanocomposite is soft and electronically Conductive, could be used as pressure/force sensor. It is shown that a compressive force applied on a cylinder of that nanocomposite increases the conductivity of material. Additionally a switch is built which turns off upon microwave irradiation. Therefore, the nanocomposites are potential candidates for different technological applications, such as: a force/pressure electrical sensor, a drug delivery device driven remotely by microwaves, pH or temperature electrical switches and an electric switch driven by microwaves.
C P Wong - One of the best experts on this subject based on the ideXlab platform.
-
Low temperature carbon nanotube film transfer via Conductive Polymer composites
Nanotechnology, 2007Co-Authors: Hongjin Jiang, Lingbo Zhu, Kyoung Sik Moon, C P WongAbstract:A low temperature process for transferring carbon nanotube (CNT) film\nfrom a silicon wafer to a copper surface via Conductive Polymer composites\nis proposed. The morphologies and electrical properties of the transferred\nCNT films were studied. An ohmic contact was formed between a CNT\nfilm and a highly Conductive Polymer composite and the resistance\nof the as-transferred CNT film was 0.08~Ω, while a semiconductor\njoint was formed between a CNT film and a high resistivity Polymer\ncomposite.
-
Conductive Polymer Composites with Large Positive Temperature Coefficients
Encyclopedia of Smart Materials, 2002Co-Authors: C P WongAbstract:Conductive Polymer composites that contain Conductive fillers such as metal powder, carbon black, and other highly Conductive particles in a nonConductive Polymer matrix have been widely used in electrostatic dissipation (ESD) and electromagnetic interference shielding (EMIS). A special group among electrically Conductive Polymer composites are Conductive Polymer composites that have large positive temperature coefficients (PTC), which in some cases are called positive temperature coefficient resistance (PTCR). The resistivity of this kind of composite increases several orders of magnitude in a narrow temperature range. This kind of smart material can change from a Conductive material to an insulating material or vice versa upon heating or cooling, respectively. The smartness of this kind material lies in this large PTC amplitude (defined as the ratio of maximum resistivity at the peak or the resistivity right after the sharp increase to the resistivity at 25°C), and also in its reversibility, its ability to adjustment the transition temperature, its low-temperature resistivity, and high-temperature resistivity. PTC behavior in a Polymer composite was first discovered by Frydman in 1945, but not much attention was paid to it originally. Because Kohler obtained a much higher PTC amplitude from high density polyethylene loaded with carbon black in 1961, this kind of temperature-sensitive materials has aroused wide research interest and also led to many very useful applications. In this article, the general theories of PTC Conductive Polymer are introduced. Carbon-black-filled Conductive Polymer composites and their PTC behavior are discussed in more detail, in regard to the effects of fillers, the Polymer matrix, and processing conditions, and additives. Applications of this kind of smart temperature-sensitive material are presented. Keywords: Conductive Polymer behavior; Positive temperature coefficient (PTC); PTC behavior; Conductive fillers; Polymer matrix; Processing conditions; Additives; Polymer composite; Application
-
Conductive Polymer composites with positive temperature coefficient
Proceedings International Symposium on Advanced Packaging Materials. Processes Properties and Interfaces (IEEE Cat. No.99TH8405), 1999Co-Authors: C P WongAbstract:Conductive Polymer composites showing large positive temperature coefficient (PTC) are made of semi-crystalline Polymer as an insulator and a conducting filler, whose concentration is close to the critical volume fraction. In this study, the resistivity and PTC behaviour of polyethylene filled with different carbon blacks were studied. Among the composites filled with different carbon blacks, N660 carbon black filled PE showed the greatest PTC behaviour. Large particle size, small surface area and small amount of the aggregate structure lead to large amplitude PTC behaviour (defined as the ratio of maximum resistivity to the resistivity at room temperature). The large PTC behaviour is due to some microscopic mechanism under the macroscopic thermal expansion of the Polymer matrix during the melting of Polymer crystal.
Kenneth J Takeuchi - One of the best experts on this subject based on the ideXlab platform.
-
Three-dimensional carbon-Conductive Polymer–silver composite air electrodes for non-aqueous metal air batteries
Journal of Composite Materials, 2013Co-Authors: Amy C Marschilok, Christopher C. Milleville, Shu Han Lee, Peiwen Chen, Esther S Takeuchi, Kenneth J TakeuchiAbstract:A novel three-component composite electrode consisting of a carbon current collector with Conductive Polymer and silver coating is described here. The composite electrode fabrication strategy is described and the composite electrode is evaluated as a cathode for oxygen reduction in non-aqueous media. This approach is utilized for the first time to prepare three-dimensionally structured carbon–Conductive Polymer–silver composites, yielding composite electrodes with ~4x the oxygen reduction capacity of their planar counterparts. Improvement of cathode oxygen reduction activity will increase current capability and power output of metal air batteries, facilitating future development of small, lightweight, and long-life power sources.
-
Electrodes for Nonaqueous Oxygen Reduction Based upon Conductive Polymer-Silver Composites
Journal of The Electrochemical Society, 2011Co-Authors: Amy C Marschilok, Christopher C. Milleville, Shu Han Lee, Shali Zhu, Esther S Takeuchi, Kenneth J TakeuchiAbstract:Progress toward the development of current collector-Conductive Polymer-silver (cc-cp-Ag) composite cathodes for nonaqueous metal air batteries is presented here, where the contribution of each component toward the overall oxygen reduction activity of the multifunctional cc-cp-Ag composite is studied. First, the effect of the chemical identity of the current collector (carbon versus gold) on the electrochemical reduction of oxygen is examined, accompanied by a Conductive Polymer deposition study. These two studies together demonstrate that a Conductive Polymer deposit can eliminate any competitive electrochemistry due to the current collector. Second, the role of the Conductive Polymer in improving physical strength of the composite electrode is evaluated using an electrode durability test. Third, a systematic study of the Ag loading effect is undertaken to determine the minimum silver loading required for significant enhancement in oxygen reduction activity. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3527992] All rights reserved.
Luheng Wang - One of the best experts on this subject based on the ideXlab platform.
-
Differential Structure for Temperature Sensing Based on Conductive Polymer Composites
IEEE Transactions on Electron Devices, 2015Co-Authors: Luheng WangAbstract:A property-induced differential structure, which includes negative temperature coefficient unit (NTCU) and positive temperature coefficient unit (PTCU), is designed to increase the sensitivity of temperature sensor based on Conductive Polymer composite. The composite with/without cellular structure is used as the sensitive material in NTCU/PTCU, which results in a decrease/an increase of the electrical resistance with the increase of the temperature. Through using NTCU and PTCU as the neighboring arms of an electrical bridge, the temperature is converted into a voltage. The results verify the feasibility of using the property-induced differential structure to improve the sensitivity.
-
An Inner-Structure-Based Differential Piezoresistive Device Made of Conductive Polymer Composite
IEEE Transactions on Electron Devices, 2014Co-Authors: Luheng Wang, Lihua ChengAbstract:To increase the absolute value of the sensitivity of flexible piezoresistive sensor based on Conductive Polymer composite under low compressive pressure, an inner-structure-based piezoresistive device is designed. The differential properties of the two subsensing elements in the device are realized by the different inner structures caused by the different Conductive phase contents of the composites. The Conductive phase content of the composite in the first subsensing element is lower than the critical Conductive phase content, and the electrical resistance of it increases with the increase in compressive pressure. The Conductive phase content of the composite in the second subsensing element is higher than the critical Conductive phase content, and the electrical resistance of it decreases with the increase in compressive pressure. Using the two subsensing elements as the neighboring arms of an electrical bridge, the conversion from the compressive pressure to the voltage is realized. The results indicate that the absolute value of the sensitivity can be improved using the inner-structure-based piezoresistive device made of Conductive Polymer composite.
-
Usage of Conductive Polymer composite as the object film of eddy current gap sensor
IEEE Transactions on Instrumentation and Measurement, 2013Co-Authors: Luheng Wang, Yanyan Han, Yannan HuangAbstract:To realize the noncontact gap measurement based on eddy current effect when the object is not Conductive, we fabricate a film made of Conductive Polymer composite and cover it on the surface of the nonConductive object. The experimental results on the lift-off effect show that the impedance of the coil with alternating current changes regularly with the variations in the distance between the coil and the composite object. This phenomenon indicates that there exists an eddy current composed of the tunneling current and the conduction current in the composite object. The results indicate that Conductive Polymer composite has the potential to replace metal as an object of an eddy current sensor system. © 2013 IEEE.
Claudia R. Rivarola - One of the best experts on this subject based on the ideXlab platform.
-
Pressure and microwave sensors/actuators based on smart hydrogel/Conductive Polymer nanocomposite
Sensors and Actuators B: Chemical, 2014Co-Authors: Rebeca E. Rivero, María A. Molina, Claudia R. Rivarola, Cesar A. BarberoAbstract:A nanocomposite is fabricated by formation of a Conductive Polymer, using in situ oxidative Polymerization, inside a thermosensitive crosslinked hydrogel. FE-SEM micrographs show the nanometric domains of the Conductive material (polyaniline, PANI) dispersed in the hydrogel matrix based on cross linked poly(N-isopropylacrylamide) (PNIPAm). The thermosensitive properties of PNIPAm and coPolymers with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) are not affected by the presence of Conductive Polymer nanoparticles. The incorporation of PANI improves the mechanical properties of the hydrogel allowing it to swell up to 30,000% without breaking. Since the Conductive Polymer absorbs strongly microwave radiation at pH < 4 and heats up, the nanocomposite containing PANI suffer phase transition upon microwave irradiation. At pH > 4, PANI is not Conductive and the nanocomposite becomes insensitive to microwaves. However, using a pH insensitive Conductive Polymer (polypyrrole, PPy) in the nanocomposite makes it sensitive to microwaves at all pH values. The nanocomposite is used in a chemomechanical actuator where drug release is driven remotely by microwave irradiation. Since the PNIPAm-co-2%AMPS/PANI nanocomposite is soft and electronically Conductive, could be used as pressure/force sensor. It is shown that a compressive force applied on a cylinder of that nanocomposite increases the conductivity of material. Additionally a switch is built which turns off upon microwave irradiation. Therefore, the nanocomposites are potential candidates for different technological applications, such as: a force/pressure electrical sensor, a drug delivery device driven remotely by microwaves, pH or temperature electrical switches and an electric switch driven by microwaves. © 2013 Elsevier B.V.
-
pressure and microwave sensors actuators based on smart hydrogel Conductive Polymer nanocomposite
Sensors and Actuators B-chemical, 2014Co-Authors: Rebeca Rivero, Claudia R. Rivarola, Maria Molina, Cesar A. BarberoAbstract:Abstract A nanocomposite is fabricated by formation of a Conductive Polymer, using in situ oxidative Polymerization, inside a thermosensitive crosslinked hydrogel. FE-SEM micrographs show the nanometric domains of the Conductive material (polyaniline, PANI) dispersed in the hydrogel matrix based on cross linked poly(N-isopropylacrylamide) (PNIPAm). The thermosensitive properties of PNIPAm and coPolymers with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) are not affected by the presence of Conductive Polymer nanoparticles. The incorporation of PANI improves the mechanical properties of the hydrogel allowing it to swell up to 30,000% without breaking. Since the Conductive Polymer absorbs strongly microwave radiation at pH 4, PANI is not Conductive and the nanocomposite becomes insensitive to microwaves. However, using a pH insensitive Conductive Polymer (polypyrrole, PPy) in the nanocomposite makes it sensitive to microwaves at all pH values. The nanocomposite is used in a chemomechanical actuator where drug release is driven remotely by microwave irradiation. Since the PNIPAm-co-2%AMPS/PANI nanocomposite is soft and electronically Conductive, could be used as pressure/force sensor. It is shown that a compressive force applied on a cylinder of that nanocomposite increases the conductivity of material. Additionally a switch is built which turns off upon microwave irradiation. Therefore, the nanocomposites are potential candidates for different technological applications, such as: a force/pressure electrical sensor, a drug delivery device driven remotely by microwaves, pH or temperature electrical switches and an electric switch driven by microwaves.