Polymer Dielectric Materials

Ahmad, Zulkifli

doi:10.5772/50638

Cited by 158 publications

(160 citation statements)

References 22 publications

(23 reference statements)

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“…Dipole moment in biomass gradually decreased as frequency increased. Therefore, dipole had shorter time to realign itself according the oscillating electric field [13], [28]. Conductive effect of microwave heating also diminished quickly in high frequency [14].…”

Section: A Effect Of Frequencymentioning

confidence: 99%

Dielectric Properties of Oil Palm Trunk Core

Jie¹,

Abdullah²,

Yusof³

et al. 2015

JOCET

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Abstract-Recent development in microwave-assisted processing of biomass materials has significantly created a need for fundamental study to understand the dielectric properties of these biomass feedstock, which could give further insight about interaction between microwave energy and biomass. In the present study, dielectric properties of oil palm trunk (OPT) core were investigated using an open-ended coaxial probe method. The dielectric properties of OPT core were determined as a function of controlling factors such as microwave frequency, biomass moisture content and fibre directions (radial, tangential and cross section). The results showed that dielectric constant of OPT core was decreased with the increasing of frequency. For dielectric loss and loss tangent, a similar trend was observed but only at low frequency (<1.8 GHz). The dielectric constant and loss of OPT core were positively correlated with its moisture content for all fibre directions. In terms of magnitude of dielectric constant and loss, radial direction showed the highest value compared to cross section and tangential which suggests radial direction has the optimum electromagnetic energy absorption and conversion.Index Terms-Oil palm trunk core, dielectric constant, dielectric loss, loss tangent. I. INTRODUCTIONAs main exporter of oil palm, Malaysia has a large area of oil palm plantation. Until December 2012, there were 5.08 million ha area of oil palm plantation covering 15% of the total land area in Malaysia [1]. Oil palm tree has short productivity life span about 25 years. During replanting, it is estimated that around 74 t/ha dry oil palm trunk (OPT) logs are produced giving availability of around 13.6 million OPT logs/year for every 100,000 hectares plantations [2]. The abundant OPT logs are mostly utilized in saw-wood, lumber, plywood, flooring and furniture manufacturing [3], [4]. In the manufacturing of plywood, only the outer part of OPT logs was peeled to be further processed into plywood while the core part comprised only soft parenchyma tissue was left out as waste [5]. The core waste could be converted into cattle feed or further processed into biofuel.For waste conversion of biomass into biofuel and materials, microwave-assisted processes such as microwavepyrolysis and microwave-drying are increasingly applied [2], [6]- [8]. Unlike conventional heat source, microwave energy has several advantageous including volumetric heating allowing bulky and high moisture biomass to be processed, minimize secondary reaction to optimize product yield also permits rapid heating therefore cost and time-saving [6] [11]. The mechanism of microwave energy on biomass involves the transport of the electrical charges by the ions present in the biomass cell wall and cellulose. Once the microwave is encountered the biomass, randomly oriented dipoles in dielectric material align themselves in a direction opposite to applied external electric field. The molecules absorb the energy and store as potential energy. By the mechanism of ionic conduction and d...

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Section: A Effect Of Frequencymentioning

confidence: 99%

Dielectric Properties of Oil Palm Trunk Core

Jie¹,

Abdullah²,

Yusof³

et al. 2015

JOCET

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“…Figure 1). In the estimation of the shaft capacitances, we assumed mean immersion depths of the electrodes of 90%, an insulation thickness of 25 µm, and a relative permittivity of 3 for the polyesterimide insulation [51].…”

Section: Additional Capacitance Contributions To the Electrode Propermentioning

confidence: 99%

Impedance detection of the electrical resistivity of the wound tissue around deep brain stimulation electrodes permits registration of the encapsulation process in a rat model

Badstuebner

Stubbe

Kroeger

et al. 2017

Journal of Electrical Bioimpedance

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An animal model of deep brain stimulation (DBS) was used in in vivo studies of the encapsulation process of custom-made platinum/iridium microelectrodes in the subthalamic nucleus of hemiparkinsonian rats via electrical impedance spectroscopy. Two electrode types with 100-µm bared tips were used: i) a unipolar electrode with a 200-µm diameter and a subcutaneous gold wire counter electrode and ii) a bipolar electrode with two parallelshifted 125-µm wires. Miniaturized current-controlled pulse generators (130 Hz, 200 µA, 60 µs) enabled chronic DBS of the freely moving animals. A phenomenological electrical model enabled recalculation of the resistivity of the wound tissue around the electrodes from daily in vivo recordings of the electrode impedance over two weeks. In contrast to the commonly used 1 kHz impedance, the resistivity is independent of frequency, electrode properties, and current density. It represents the ionic DC properties of the tissue. Significant resistivity changes were detected with a characteristic decrease at approximately the 2nd day after implantation. The maximum resistivity was reached before electrical stimulation was initiated on the 8th day, which resulted in a decrease in resistivity. Compared with the unipolar electrodes, the bipolar electrodes exhibited an increased sensitivity for the tissue resistivity.

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“…The actuation voltage plays a major role in portable devices, because it determines the use of small power sources (batteries) that is critical for device development. The dielectric constant of a material relates to the permittivity of that material (Ahmad, 2012). Permittivity expresses the ability of insulating material to polarise in response to an applied electric field (Ahmad, 2012).…”

Section: Figure 17mentioning

confidence: 99%

Review: <i>Biosensors for the detection of Escherichia coli</i>

Maas

Perold

Dicks

2017

WSA

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The supply of safe potable water, free from pathogens and chemicals, requires routine analyses and the application of several diagnostic techniques. Apart from being expensive, many of the detection methods require trained personnel and are often time-consuming. With drastic climate changes, severe droughts, increases in population and pollution of natural water systems, the need to develop ultrasensitive, low-cost and hand-held, point-of-use detection kits to monitor water quality is critical. Although Escherichia coli is still considered the best indicator of water quality, cell numbers may be below detection limits, or the cells may be non-culturable and thus only detected by DNA amplification. A number of different biosensors have been developed to detect viable, dead or non-culturable microbial cells and chemicals in water. This review discusses the differences in these biosensors and evaluates the application of microfluidics in the design of ultra-sensitive nano-biosensors.

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Polymer Dielectric Materials

Cited by 158 publications

References 22 publications

Dielectric Properties of Oil Palm Trunk Core

Dielectric Properties of Oil Palm Trunk Core

Impedance detection of the electrical resistivity of the wound tissue around deep brain stimulation electrodes permits registration of the encapsulation process in a rat model

Review: <i>Biosensors for the detection of Escherichia coli</i>

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