Towards Accurate Measurement of the Frequency Dependence of Capacitance and Resistance Standards up to 10 MHz

Awan, S.A.; Kibble,

doi:10.1109/cpem.2004.305410

Cited by 5 publications

(11 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The electric current was measured through the inner electrodes of the probe. Separation of stimulation and sensing terminals allows minimization of possible secondary effects, such as inductance of cables or stray capacitances that can influence the accuracy of the impedance measurement [15]. We analyzed the impedance of the samples in the 10 3 –10 7 Hz range.…”

Section: Methodsmentioning

confidence: 99%

Sodium Concentration Measurement during Hemodialysis through Ion-Exchange Resin and Conductivity Measure Approach: In Vitro Experiments

et al. 2013

View full text Add to dashboard Cite

Sodium measurement during hemodialysis treatment is important to preserve the patient from clinical events related to hypo- or hyper-natremia Usually, sodium measurement is performed through laboratory equipment which is typically expensive, and requires manual intervention. We propose a new method, based on conductivity measurement after treatment of dialysate solution through ion-exchange resin. To test this method, we performed in vitro experiments. We prepared 40 ml sodium chloride (NaCl) samples at 280, 140, 70, 35, 17.5, 8.75, 4.375 mEq/l, and some “mixed samples”, i.e., with added potassium chloride (KCl) at different concentrations (4.375-17.5 mEq/l), to simulate the confounding factors in a conductivity-based sodium measurement. We measured the conductivity of all samples. Afterwards, each sample was treated for 1 min with 1 g of Dowex G-26 resin, and conductivity was measured again. On average, the difference in the conductivity between mixed samples and corresponding pure NaCl samples (at the same NaCl concentration) was 20.9%. After treatment with the exchange resin, it was 14.7%, i.e., 42% lower. Similar experiments were performed with calcium chloride and magnesium chloride as confounding factors, with similar results. We also performed some experiments on actual dialysate solution during hemodialysis sessions in 15 patients, and found that the correlation between conductivity measures and sodium concentration improved after resin treatment (R=0.839 before treatment, R=0.924 after treatment, P<0.0001). We conclude that ion-exchange resin treatment coupled with conductivity measures may improve the measurement of sodium compared to conductivity measures alone, and may become a possible simple approach for continuous and automatic sodium measurement during hemodialysis.

show abstract

Section: Methodsmentioning

confidence: 99%

Sodium Concentration Measurement during Hemodialysis through Ion-Exchange Resin and Conductivity Measure Approach: In Vitro Experiments

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The IA was first calibrated using one of our 100 Ω HF-CRSs [41], since the G-4TP impedance device had a DC value of R 4P ≃ 104 V. The IA instruments use number of range resistors internally, such as 100 and 1 kΩ etc., against which a DUT is measured in a comparison bridge. It is these range resistors which require calibration against a standard of known frequency response over the broad frequency range of the IA.…”

Section: Calibration Of the 4tp Impedance Analysermentioning

confidence: 99%

Radio‐frequency transport Electromagnetic Properties of chemical vapour deposition graphene from direct current to 110 MHz

Awan

Pan²,

Taan³

et al. 2015

IET Circuits, Devices & Systems

View full text Add to dashboard Cite

We report measurement of the radio-frequency (RF) transport electromagnetic properties of chemical vapour deposition (CVD) graphene over the DC to 110 MHz frequency range at room temperature. Graphene on Si/SiO 2 substrate was mounted in a shielded four terminalpair (4TP) adaptor which enabled direct connection to a calibrated precision impedance analyser for measurements. Good agreement is observed for the DC four-probe resistance and the 4TP resistance at 40 Hz, both yielding R ≈ 104 Ω. In general the apparent graphene channel electromagnetic properties are found to be strongly influenced by the substrate parasitic capacitance and resistance, particularly for high-frequencies f > 1 MHz. A phenomenological lumped-parameter equivalent circuit model is presented which matches the frequency response of the graphene 4TP impedance device over approximately seven decades of the frequency range of the applied transport alternating current. Based on this model, it is shown for the first time, that the intrinsic graphene channel resistance of the 4TP device is frequency-independent (i.e. dissipationless) with R G ≈ 105 Ω or sheet resistance of approximately 182 Ω / □. The parasitic substrate impedance of the device is found shunt R G with R P ≈ 2.2 Ω in series with C P ≈ 600 pF. These results suggest that our new RF 4TP method is in good agreement with the conventional DC four-probe method for measuring the intrinsic sheet resistance of single-atom thick materials and could potentially open up new applications in RF electronics, AC quantum Hall effect metrology and sensors based on graphene 4TP devices operating over broad range of frequencies.

show abstract

“…In this study, lower frequency values were not considered to avoid having possible confounding factors related to electrode polarization. e cell was characterized by four platinum electrodes ( Figure 2) for possible separation between stimulation and sensing terminals and consequent minimization of possible secondary effects (inductance of cables or parasitic capacitances) [10].…”

Section: Impedance Equipment and Measurement Approachmentioning

confidence: 99%

Electroimpedance Spectroscopy for the Measurement of the Dielectric Properties of Sodium Chloride Solutions at Different Glucose Concentrations

Sbrignadello

Tura

Ravazzani

2013

Journal of Spectroscopy

View full text Add to dashboard Cite

We investigated possible variations of impedance values in samples of sodium chloride solution (sodium chloride 0.9%) with glucose at different concentrations, ranging from 5000 to around 75 mg/dL. The sodium chloride solution (either saline physiological solution) was chosen since it has similarities to blood but no cell components, which may be confounding factors in this study. Special focus was on the effect of stirring and of temperature variations on the impedance spectrum of samples at different glucose concentrations. We found that variations in glucose concentration directly affect the impedance modulus of the sample both in static conditions and in dynamic conditions due to stirring, as well as at both room temperature and at increased temperature. In fact, even if the impedance variations were often small (around 3-4 mΩper mg/dL), they were usually clearly measurable. These findings may be the basis for possible development of a new approach, based on impedance technology, for the noninvasive monitoring of glycaemia.

show abstract

Towards Accurate Measurement of the Frequency Dependence of Capacitance and Resistance Standards up to 10 MHz

Cited by 5 publications

References 10 publications

Sodium Concentration Measurement during Hemodialysis through Ion-Exchange Resin and Conductivity Measure Approach: In Vitro Experiments

Sodium Concentration Measurement during Hemodialysis through Ion-Exchange Resin and Conductivity Measure Approach: In Vitro Experiments

Radio‐frequency transport Electromagnetic Properties of chemical vapour deposition graphene from direct current to 110 MHz

Electroimpedance Spectroscopy for the Measurement of the Dielectric Properties of Sodium Chloride Solutions at Different Glucose Concentrations

Contact Info

Product

Resources

About