scholarly journals A Low Excitation Working Frequency Capacitively Coupled Contactless Conductivity Detection (C4D) Sensor for Microfluidic Devices

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6381
Author(s):  
Yuchen He ◽  
Qiang Huang ◽  
Yu He ◽  
Haifeng Ji ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Conductivity Measurement ◽  
Microfluidic Devices ◽  
Experimental Results ◽  
Concentration Measurement ◽  
Ion Concentration ◽  
Capacitively Coupled ◽  
Contactless Conductivity Detection ◽  
Lc Circuit ◽  
Li Ion ◽  
Working Frequency

In this work, a new capacitively coupled contactless conductivity detection (C4D) sensor for microfluidic devices is developed. By introducing an LC circuit, the working frequency of the new C4D sensor can be lowered by the adjustments of the inductor and the capacitance of the LC circuit. The limits of detection (LODs) of the new C4D sensor for conductivity/ion concentration measurement can be improved. Conductivity measurement experiments with KCl solutions were carried out in microfluidic devices (500 µm × 50 µm). The experimental results indicate that the developed C4D sensor can realize the conductivity measurement with low working frequency (less than 50 kHz). The LOD of the C4D sensor for conductivity measurement is estimated to be 2.2 µS/cm. Furthermore, to show the effectiveness of the new C4D sensor for the concentration measurement of other ions (solutions), SO42− and Li+ ion concentration measurement experiments were also carried out at a working frequency of 29.70 kHz. The experimental results show that at low concentrations, the input-output characteristics of the C4D sensor for SO42− and Li+ ion concentration measurement show good linearity with the LODs estimated to be 8.2 µM and 19.0 µM, respectively.

Microfluidic devices with integrated dual-capacitively coupled contactless conductivity detection to monitor binding events in real time

2014 ◽  
Vol 192 ◽  
pp. 239-246 ◽  
Author(s):  
Wendell Karlos Tomazelli Coltro ◽  
Rodrigo de Santis Neves ◽  
Artur de Jesus Motheo ◽  
José Alberto Fracassi da Silva ◽  
Emanuel Carrilho
Keyword(s):  
Real Time ◽  
Microfluidic Devices ◽  
Conductivity Detection ◽  
Capacitively Coupled ◽  
Contactless Conductivity Detection

On-chip capacitively coupled contactless conductivity detection using “injected” metal electrodes

The Analyst ◽  
2013 ◽  
Vol 138 (15) ◽  
pp. 4275 ◽  
Author(s):  
Leigh D. Thredgold ◽  
Dmitriy A. Khodakov ◽  
Amanda V. Ellis ◽  
Claire E. Lenehan
Keyword(s):  
Metal Electrodes ◽  
Conductivity Detection ◽  
Capacitively Coupled ◽  
Contactless Conductivity Detection ◽  
On Chip

scholarly journals Influence of electrodes area ratios and the discharge volume in RF capacitively coupled plasma

2019 ◽  
Vol 11 (20) ◽  
pp. 1-8
Author(s):  
Moyad Abdullah Ahmad
Keyword(s):  
Glow Discharge ◽  
Cone Angle ◽  
Experimental Results ◽  
Rf Power ◽  
Capacitively Coupled ◽  
Discharge Volume ◽  
Capacitively Coupled Plasma ◽  
Harmonic Distortions

Experimental results on harmonic distortions in 13.56 MHz RF Argon glow discharge using different grounded electrodes areas and electrodes spacing are presented. The experiment is carried out at four pressure values. RF power values used are between 20 and 90 watts. The results indicate significant increase in distortions at two specific values of the cone angle enclosing the two electrodes within its geometrical volume. The computation of the cone head angle gave the symmetry discharge or asymmetry as well as when the angle is small the condition is near symmetry discharge associated with decrease in the nonlinearity.

Understanding Capacitively Coupled Contactless Conductivity Detection in Capillary and Microchip Electrophoresis. Part 1. Fundamentals

2005 ◽  
Vol 17 (13) ◽  
pp. 1198-1206 ◽  
Author(s):  
José Geraldo Alves Brito-Neto ◽  
José Alberto Fracassi da Silva ◽  
Lucas Blanes ◽  
Claudimir Lucio do Lago
Keyword(s):  
Microchip Electrophoresis ◽  
Conductivity Detection ◽  
Capacitively Coupled ◽  
Contactless Conductivity Detection

scholarly journals Removal of Zn(II) By Magnetic Composite Adsorbent: Synthesis, Performance, And Mechanism

2021 ◽  
Author(s):  
Shuang Yi ◽  
Binqin Bao ◽  
Weifeng Song ◽  
MuDdan Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Experimental Results ◽  
Ion Concentration ◽  
Magnetic Composite ◽  
Order Kinetic ◽  
Exchange Effect ◽  
Composite Adsorbent ◽  
Composite Gel ◽  
Infrared Spectrometer ◽  
Pseudo Second Order

Abstract In this study, L-methionine and nano-Fe3O4 were encapsulated and cured on sodium alginate by the ionic cross-linking method to form magnetic composite gel spheres (SML). The influence of adsorbent dosages, pH, reaction time, and initial ion concentration on the ability of the gel spheres to adsorb Zn(II) was investigated. The experimental results indicated that under the optimum conditions, the maximum amount of Zn(II) adsorbed by the adsorbent gel spheres reached 86.84 mgˑg-1. The experimental results of adsorption indicate that the reaction process of this adsorbent fits well with the Langmuir and pseudo-second-order kinetic models and is a heat absorption reaction. The results of the adsorption investigation of the coexistence system showed that the adsorbent would preferentially adsorb Pb(II), and the adsorption efficiency of Zn(II) decreased when the concentration of interfering ions increased. The structure of this adsorbent and the adsorption mechanism were investigated by Fourier transform infrared spectrometer, thermal gravimetric analyzer, vibrating sample magnetometer, scanning electron microscope, Brunner-Emmet-Teller measurements, and X-ray photoelectron spectroscopy. The results show that this magnetic composite adsorbent is a mesoporous material with superior adsorption performance, and the amino and carboxyl groups on it react with Zn(II) via ligand chelation; the ion exchange effect of Ca(II) also plays a role. The desorption-adsorption experiments of the adsorbent indicated that the adsorption amount of Zn(II) was maintained at a higher level after several cycles, and the loss of Fe was approximately 0.2%. In summary, SML is an ideal adsorbent for environmental protection.

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