scholarly journals Buoyancy-Free Janus Microcylinders as Mobile Microelectrode Arrays for Continuous Microfluidic Biomolecule Collection within a Wide Frequency Range: A Numerical Simulation Study

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 289 ◽  
Author(s):  
Weiyu Liu ◽  
Yukun Ren ◽  
Ye Tao ◽  
Hui Yan ◽  
Congda Xiao ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Particle Surface ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Main Body ◽  
Wide Field ◽  
Frequency Range ◽  
Field Frequency ◽  
Ac Electrokinetics ◽  
Induced Charge

We numerically study herein the AC electrokinetic motion of Janus mobile microelectrode (ME) arrays in electrolyte solution in a wide field frequency, which holds great potential for biomedical applications. A fully coupled physical model, which incorporates the fluid-structure interaction under the synergy of induced-charge electroosmotic (ICEO) slipping and interfacial Maxwell stress, is developed for this purpose. A freely suspended Janus cylinder free from buoyancy, whose main body is made of polystyrene, while half of the particle surface is coated with a thin conducting film of negligible thickness, will react actively on application of an AC signal. In the low-frequency limit, induced-charge electrophoretic (ICEP) translation occurs due to symmetric breaking in ICEO slipping, which renders the insulating end to move ahead. At higher field frequencies, a brand-new electrokinetic transport phenomenon called “ego-dielectrophoresis (e-DEP)” arises due to the action of the localized uneven field on the inhomogeneous particle dipole moment. In stark contrast with the low-frequency ICEP translation, the high-frequency e-DEP force tends to drive the asymmetric dipole moment to move in the direction of the conducting end. The bidirectional transport feature of Janus microspheres in a wide AC frequency range can be vividly interpreted as an array of ME for continuous loading of secondary bioparticles from the surrounding liquid medium along its direction-controllable path by long-range electroconvection. These results pave the way for achieving flexible and high-throughput on-chip extraction of nanoscale biological contents for subsequent on-site bioassay based upon AC electrokinetics of Janus ME arrays.

Analysis of Sound Absorption Properties of Three-Leaf Microperforated Panel Absorbers without a Rigid Backing

2014 ◽  
Vol 937 ◽  
pp. 465-471
Author(s):  
Xiao Ling Gai ◽  
Xian Hui Li ◽  
Rui Wu ◽  
Bin Zhang ◽  
Jun Juan Zhao
Keyword(s):  
Sound Absorption ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Structure Design ◽  
Frequency Region ◽  
Theoretical Development ◽  
Frequency Range ◽  
Absorption Properties ◽  
High Frequency Region ◽  
Energy Dissipated

Microperforated panel (MPP) absorbers have been developed rapidly and used in many fields in recent years. First, based on the Maa’s theory, the theoretical development of MPP is reviewed in this paper. Furthermore, structure design and processing technology of MPP are introduced. Finally, the further development of MPP is discussed. Based on the MPP theory and electro-acoustical equivalent circuit principle, sound absorption properties of three-leaf microperforated panel (TMPP) absorbers without a rigid backing are studied to broaden the sound absorption bandwidth of MPP structure. Simulation results show that TMPP absorbers without a rigid backing have two resonance peaks and the energy dissipated coefficient remains constant in the low frequency range. The resonance frequency moves toward low frequency region with the increasing of the distance, thickness and pore diameter of MPP and moves toward high frequency region with the increasing of the perforation when other parameters keep invariant. The energy dissipated coefficient more than 0.5 over 8 octaves by choosing proper parameters. In conclusion, TMPP absorbers without a rigid backing have good sound absorption properties in a wide frequency range.

Microstructure and Electrical Properties of Calcium Copper Titanate Ceramics

2007 ◽  
Vol 561-565 ◽  
pp. 551-555 ◽  
Author(s):  
Lai Jun Liu ◽  
Hui Qing Fan
Keyword(s):  
Electrical Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Cell Parameters ◽  
Grain Sizes ◽  
Calcium Copper Titanate ◽  
Titanate Ceramics

The effect of stoichiometry, i.e. Ca/Cu ratios (CaCu3xTi4O12, x = 0.8, 0.9, 1.0, 1.1 and 1.2) on the microstructure and electrical properties was investigated. The grain sizes of CaCu3xTi4O12 composition increased sharply with the increase of copper, from ~1 μm with x = 0.8 to ~50 μm with x = 1.2. The real part of dielectric permittivity changed dramatically, the pellet with x = 1.0 had the highest dielectric permittivity ~160, 000 at 1 kHz. Furthermore, the dielectric permittivity of all pellets was impressively large values (between 10, 000 to 1, 000,000 at 100 Hz) and was nearly constant over a wide frequency range between 100 Hz to ~100 MHz. However, the dielectric permittivity of CaCu3xTi4O12 composition is not consistent with the amount of copper and cell parameters and grain sizes. Impedance spectroscopy exhibited that the CaCu3xTi4O12 composition had two semicircle at least at high frequency (~ 107 Hz) and low frequency (<100 Hz), respectively. The grain and grain boundary of the compositions had different impedance and relaxation behavior.

Wide Frequency Characterization of Magnetic Properties of Commercial LTCC Ferrite Material

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000224-000231
Author(s):  
Nelu Blaž ◽  
Andrea Marić ◽  
Goran Radosavljević ◽  
Nebojša Mitrović ◽  
Ibrahim Atassi ◽  
...  
Keyword(s):  
Dispersion Model ◽  
Low Frequency ◽  
Hysteresis Loops ◽  
Wide Frequency Range ◽  
Complex Permeability ◽  
Frequency Range ◽  
Dispersion Parameters ◽  
Simple Method ◽  
Microwave Engineering ◽  
Characterization Procedure

Complex magnetic permeability and hysteresis characteristic are key parameters that determine properties of ferrite components. This paper offers effective, accurate and simple method for complex permeability determination of LTCC (Low Temperature Co-fired Ceramic) ferrite sample at wide frequency range (up to 1 GHz). Presented research can be found to be of importance in fields of ferrite components design and application, as well as RF and microwave engineering. The characterization sample is a stack of LTCC tapes forming a toroidal shape structure. Commercially available ferrite tape ESL 40012 was used and standard LTCC processing applied for the sample fabrication. Permeability is determined in the frequency range from 10 kHz to 1 GHz and characterization procedure is divided in two segments - for low and high frequencies. Low frequency measurements (from 10 kHz to 1000 kHz) are performed using LCZ meter and discrete turns of wire, while a short coaxial sample holder and Vector Network Analyzer were used for the higher frequency range (from 1000 kHz to 1 GHz). Hysteresis properties of this material are also determined. B-H hysteresis loops were measured with BROCKHAUS Tester MPG 100D system using the maximum excitation of 2 kA/m and frequencies of 50 Hz, 500 Hz and 1000 Hz. In addition, we presented another important factor in the practical design, the temperature variation of the permeability dispersion parameters. Obtained results show good agreement with datasheet values given by the manufacturer at lower frequencies and are in good correlation with results extracted from developed dispersion model at higher frequencies.

LOW FREQUENCY MODES PROBED BY TIME-DOMAIN OPTICAL KERR EFFECT SPECTROSCOPY

1996 ◽  
Vol 10 (11) ◽  
pp. 1229-1272 ◽  
Author(s):  
S. KINOSHITA ◽  
Y. KAI ◽  
T. ARIYOSHI ◽  
Y. SHIMADA
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Kerr Effect ◽  
Low Frequency ◽  
Great Accuracy ◽  
Wide Frequency Range ◽  
Optical Kerr Effect ◽  
Spectroscopic Techniques ◽  
Frequency Range ◽  
Debye Relaxation

The principle and application of ultrafast optical Kerr effect (OKE) spectroscopy have been reviewed. This spectroscopy is shown to be very useful to investigate low frequency modes in disordered materials and the obtained data are directly comparable with frequency-domain light scattering spectroscopy. Experimental study to show the consistency between the time- and frequency-domain spectroscopy has been performed for liquid nitrobenzene and the excellent agreement is attained over three orders of magnitude in frequency range. It is also shown that the result obtained by the OKE measurement is consistent with that obtained by four wave mixing spectroscopy. Combination of these spectroscopic techniques is particularly suited for the investigation of low frequency modes because a wide frequency range is covered with great accuracy. Several remarks concerning the OKE spectroscopy are presented such as the breakdown of Debye relaxation model and various interference effects which may distort the time-domain data.

Molecular relaxation in Chitosan films in GHz frequency range

2014 ◽  
Vol 1613 ◽  
pp. 83-88
Author(s):  
Siva Kumar-Krishnan ◽  
Evgen Prokhorov ◽  
Gabriel Luna-Barcenas
Keyword(s):  
Activation Energy ◽  
Low Frequency ◽  
Bound Water ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Temperature Range ◽  
A Value ◽  
Chitosan Films ◽  
First Time

ABSTRACTThe molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.

scholarly journals Dispersion of Switching Processes in Ferroelectric Ceramics

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
O. V. Malyshkina ◽  
Anton Yurievich Eliseev ◽  
R. M. Grechishkin
Keyword(s):  
Electric Fields ◽  
Heating Temperature ◽  
Low Frequency ◽  
High Amplitude ◽  
Wide Frequency Range ◽  
The Self ◽  
Ferroelectric Ceramics ◽  
Field Frequency ◽  
Self Heating ◽  
Electric Field Frequency

The influence of the switching processes on self-heating of ferroelectric PZT ceramics samples was studied in high-amplitude sine and meander electric fields in a wide frequency range of 50 to 1500 Hz. It is shown that the linear dependence of the self-heating temperature on the electric field frequency is observed only in low-frequency region. It was found that there exists a maximum on the frequency dependence of the self-heating temperature. The critical frequency fcr corresponding to this maximum depends on both the properties of the material and geometry of the sample.

Synthesis and Characterization of Magnetoelectric Nanocomposites

2009 ◽  
Vol 155 ◽  
pp. 173-188
Author(s):  
Kanhaiya Lal Yadav
Keyword(s):  
Annealing Temperature ◽  
Strong Dependence ◽  
Low Frequency ◽  
Magnetic Characteristics ◽  
Frequency Range ◽  
Field Frequency ◽  
Maximum Value ◽  
Citrate Gel Process ◽  
Small Crystallite

A simple citrate gel process was used to prepare nanocomposites of xCuFe2O4–(1−x)BiFeO3 (henceforth, CFBF) and xNi0.75Co0.25Fe2O4-(1-x)BiFeO3 (henceforth, NCFBF) with x=0.1, 0.2, 0.3 and 0.4. The phase was found to be formed at 500 °C and 700 °C for CFBF and NCFBF respectively. TEM observation showed that the average particles size is around 40 nm. The variation of the dielectric constant and the dielectric loss with frequency showed dispersion in the low frequency range. All the samples exhibit strong magnetic characteristics. The coercivity and squareness increased with the increase in annealing temperature and were maximum for samples annealed at 500°C and 700°C for CFBF and NCFBF nanocomposites, respectively, and further decrease in coercivity is attributed to decrease in aspect ratio and pinning effects in the nanocrysatllites. The ME coefficient αE showed strong dependence on HBias and maximum value of ME coefficients were 303 and 309 mV/cm Oe at magnetic field frequency of 50 kHz for CFBF and NCFBF nanocomposites respectively. The large values of ME coefficients are attributed to low coercivity, large magnetization and small crystallite size of constituent phases.

scholarly journals Experimental Study of Raman Spectra of Some Aromatic Hydrocarbons

2020 ◽  
Vol 65 (4) ◽  
pp. 284
Author(s):  
B. Eshchanov ◽  
Sh. Otajonov ◽  
G. Mukhamedov ◽  
I. Doroshenko ◽  
O. Karpova ◽  
...  
Keyword(s):  
Experimental Study ◽  
Aromatic Hydrocarbons ◽  
Low Frequency ◽  
Semiempirical Method ◽  
Wide Frequency Range ◽  
Torsional Vibrations ◽  
Benzene Derivatives ◽  
Frequency Range ◽  
Frequency Spectra ◽  
Potential Barriers

The vibrational spectra of liquid aromatic hydrocarbons – bromobenzene, dioxane, toluene – are studied in a wide frequency range by means of Raman spectroscopy. The manifestation of torsional vibrations of individual groups of atoms is established from the obtained data on the low-frequency spectra. The possibility of using a semiempirical method for calculating the potential barriers of methyl and halide groups in benzene derivatives is shown.

scholarly journals Second Order Low Pass RC Active Filter for Low Frequency Signal Processing

2020 ◽  
pp. 220-223
Keyword(s):  
Communication Systems ◽  
Low Frequency ◽  
Cmos Technology ◽  
Wide Frequency Range ◽  
Second Order ◽  
Frequency Range ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Cadence Tool

The different parameters define the characteristics of filter for various applications like: Biomedical applications, Defense communication systems, Wireless Communication systems etc. The mostly measured parameters for filter designing are frequency range, cut off frequency, gain, power consumption, and noise. In this paper, our work focuses on frequency range measurement at cut off frequency of Hz of second order low pass filter with designed using CMOS technology for IC fabrication. The proposed circuit gives the high frequency range at low frequency (100Hz – 10MHz) with 1mV 50Hz low power supply using complementary compound pair on the value of R=1K and C=10pH. This second order active low pass filter provides high amplification at the output with 4.861V. It is implemented and simulated on 180nm Cadence tool in terms of wide frequency range or band at cut off frequency of Hz to MHz.

Research on Nonlinear Modeling for Power Transformer over Wide Frequency Range

2013 ◽  
Vol 446-447 ◽  
pp. 832-836 ◽  
Author(s):  
Zhong Yuan Zhang ◽  
Xin Ge ◽  
Zeng Chao Wang
Keyword(s):  
Steady State ◽  
High Frequency ◽  
Power Transformer ◽  
Nonlinear Modeling ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Frequency Module ◽  
Power Frequency ◽  
Box Method

This paper proposes a new nonlinear broadband model of the power transformer which is both fit for steady state and transient simulation in power system. The model consists of high-frequency module and low-frequency module in parallel. Based on the black-box method, the high-frequency block is built in the form of π-type equivalent circuit, and the low-frequency block is in the form of conventional gamma-type circuit, in which core saturation characteristic is expressed by a nonlinear inductor. A power transformer is studied in the laboratory, simulations and experiments are carried out in case of power-frequency steady state, excitation currents distortions, lightning overvoltage, and very fast transient overvoltages (VFTO) respectively. The comparisons between the simulated and measured results verify the feasibility and validity of the model.

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