Supercapacitive Admittance Tomoscopy

Gamby, Jean; Abid, Jean‐Pierre; Girault, Hubert H.

doi:10.1021/ja050602o

Cited by 25 publications

(35 citation statements)

References 29 publications

(26 reference statements)

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“…However, in the previous study [10], the impedance between the microelectrodes and the microchannel through the bulk of the PET substrate was not considered since it has been reported that the resistance is large enough that it could be disregarded. Thus, impedance measurements performed here are undertaken on the device when it is empty or filled with a sodium chloride solution in order to reach a better understanding of the PET impedance contribution in the global response.…”

Section: Resultsmentioning

confidence: 99%

“…The microchip device used in this work was described elsewhere [10,13]. Some modifications have been made and will be outlined hereafter.…”

Section: Methodsmentioning

confidence: 99%

“…However, electrochemical detection (ECD) offers specific advantages for microfluidic systems due to its small size, portability, low cost, high sensitivity, and high selectivity using a proper choice of detection potential and/or electrode material [8]. An additional advantage of ECD is the simplicity of the instrumentation, resulting in low electrical power requirements for in-field use [9][10][11][12]. Electrochemical impedance spectroscopy (EIS) is a sensitive analysis method for biological samples [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Gamby et al [10,13] described microchannels and contact-free microelectrodes using a microfabrication process based on photoablation of polyethylene terephthalate (PET). This process is an attractive alternative to other expensive, laborious, and time-consuming methods for microchannel fabrication such as photolithography approaches.…”

Section: Introductionmentioning

confidence: 99%

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Polymer microchip impedance spectroscopy through two parallel planar embedded microelectrodes: Understanding the impedance contribution of the surrounding polymer on the measurement accuracy

Kechadi

Gamby

Chaal

et al. 2013

Electrochimica Acta

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a b s t r a c tThe present work describes a new methodology for contact free impedance of a solution in a polymer microchip taking into account the role played by the surrounding polymer on the impedance accuracy. Measurements were carried out using a photoablated polyethylene terephthalate (PET) microchannel above two embedded microband electrodes. The impedance diagrams exhibit a loop from high frequencies to medium frequencies (1 MHz-100 Hz) and a capacitive behavior at low frequencies (100-1 Hz). The impedance diagrams were corrected by eliminating from the global microchip response the contribution of the impedance of the PET layer between the two microband electrodes. This operation enables a clear observation of the impedance in the microchannel solution, including the bulk solution contribution and the interfacial capacitance related to the surface roughness of the photoablated microchannel. Models for the impedance of solutions of varying conductivity showed that the capacitance of the polymer-solution interface can be modeled by a constant phase element (CPE) with an exponent of 0.5. The loop diameter was found to be proportional to the microchannel resistivity, allowing a cell constant around 4.93 × 10 5 m −1 in contactless microelectrodes configuration.

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Section: Resultsmentioning

confidence: 99%

“…The microchip device used in this work was described elsewhere [10,13]. Some modifications have been made and will be outlined hereafter.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Polymer microchip impedance spectroscopy through two parallel planar embedded microelectrodes: Understanding the impedance contribution of the surrounding polymer on the measurement accuracy

Kechadi

Gamby

Chaal

et al. 2013

Electrochimica Acta

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“…Based on the same concept, non-contact impedance spectroscopy through polymer microchannel provides a thorough method for probing biomolecular interactions on insulated materials [10] with related applications in sensors [11,12], DNA-sensors [6,7], and enzyme biosensors [13]. With this non-conventional impedance spectroscopy, since the embedded microelectrodes are not in direct contact with the solution, the alternating potential difference imposed between the two microelectrodes is modulated in high frequency range.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Kinetics of Antibody Adsorption onto Polyethylene Terephthalat (PET) Modified with Gold Nanoparticles in Flow Microchannel

Kechadi¹,

Sotta²,

Gamby³

2014

J Flow Chem

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The real-time monitoring of the adsorption kinetic of antibody onto polyethylene terephthalate (PET) modified with gold nanoparticles (NPs) is performed into a dielectric flow microchannel. The principle is based on the microelectrode-dielectric interface excitation by a modulated voltage excitation through the dielectric layer with high frequency range. The set-up configuration using a homemade current-to-voltage converter has been developed for fast monitoring of biomolecule adsorption without direct electrical contact of microelectrodes with the microchannel flow. The change in the interfacial admittance, related to the output voltage measured through the microchip, during antibody incubation, gives information on the kinetics involved while antibodies are adsorbed at the interface. An example of adsorption on PET modified with gold NPS was taken. Experimental data were fit with the Langmuir equation and a good correlation was obtained with this latter, where the equilibrium constant, K, was found as 1.55 × 10 8 M −1 with a limit of detection for antibody concentration without depletion equal to 8.25 nM.

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Contact Free Impedance Methodology for Investigating Enzymatic Reactions into Dielectric Polymer Microchip

Kechadi¹,

Sotta²,

Gamby³

et al. 2013

Electroanalysis

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A methodology for free contact microchannel impedance measurements through a dielectric microchip was developed for monitoring the kinetics of enzymatic reactions. For that purpose, we propose a procedure which consists of subtracting the impedance contribution of the dielectric polymer layer, which separates the two parallel microband electrodes embedded in it, from the global microchip impedance. This operation allows microchannel impedance enhancement for real time monitoring of impedance modulus changes without direct electrical contact. Application for determination of kinetic parameters of enzyme‐substrate reaction independently of optical or electrochemical properties of the substrates is demonstrated. Hydrolysis 4‐nitrophenylphosphate (pNPP) and 4‐aminophenylphosphate (pAPP), which are two substrates for Alkaline Phosphatase (ALP), are taken as examples. Moreover, signal amplification response of the impedance modulus is achieved by the use of superparamagnetic microbeads as enzyme supports. Plotting the maximum rate against the ALP concentration gives rise to straight lines with a slope that is the hydrolysis catalytic pseudo first‐order rate constant, kcat. Sensitivity, selectivity and reproducibility of these measurements have been demonstrated comparatively with both substrates. kcat values were 103 s−1 and 52 s−1 with pAPP and pNPP, respectively.

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Supercapacitive Admittance Tomoscopy

Cited by 25 publications

References 29 publications

Polymer microchip impedance spectroscopy through two parallel planar embedded microelectrodes: Understanding the impedance contribution of the surrounding polymer on the measurement accuracy

Polymer microchip impedance spectroscopy through two parallel planar embedded microelectrodes: Understanding the impedance contribution of the surrounding polymer on the measurement accuracy

Investigating the Kinetics of Antibody Adsorption onto Polyethylene Terephthalat (PET) Modified with Gold Nanoparticles in Flow Microchannel

Contact Free Impedance Methodology for Investigating Enzymatic Reactions into Dielectric Polymer Microchip

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