scholarly journals Modification of Electrode Surfaces Via Chromium Deposition [Capital University]

2019 ◽  
Author(s):  
David Kenneth Lankitus ◽  
William J. Clark
Keyword(s):  
Microelectrode Array ◽  
Microelectrode Arrays ◽  
Differential Pulse ◽  
Glassy Carbon Electrodes ◽  
Electrode Surfaces ◽  
Undergraduate Laboratory ◽  
Covered Electrodes ◽  
Source Current ◽  
Reduction And Oxidation ◽  
Electrode Coverage

Microelectrode arrays are useful in electrochemical detection, having the advantage of lower signal to noise ratios compared to traditional sized electrodes. However, they can be expensive and complex to produce. A cheap, easy to produce, and renewable method of preparing microelectrode arrays in an undergraduate laboratory is therefore highly valuable. This project explores the efficacy of producing a random-microelectrode array by partial deposition of chromium onto an electrode surface, enhancing the study of electrochemistry in undergraduate laboratories. This study uses gold, platinum, and glassy carbon electrodes, ruthenium hexamine as a model electron acceptor, and K2Cr2O7 solution as a chromium source. Current results have produced evidence of microelectrode formation. All electrodes have been completely and partially inactivated by chromium deposition via reduction of Cr(VI) to Cr(III) and can be reactivated electrochemically as well. Deposition is achieved through direct current potential amperometry (DCPA) and illustrated through both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CVs reveal reduction and oxidation of ruthenium hexamine with uncovered electrodes and a loss of reduction and oxidation with chromium covered electrodes. DPVs reveal similar results. The partial deposition that has been achieved can be difficult to replicate and varies with the electrode material. Background CV scans differ in active and inactivated electrodes, suggesting that capacitance varies with deposition. By measuring capacitance compared to deposition, insight regarding electrode coverage may be found. Experiments aimed at replicating published material on microelectrode production (Anal. Chem. 2016, 88, 1753-1759) are also being performed to demonstrate similarities between results. Comparison to published work and refined methodology is needed to provide strong, reproducible evidence of random-microelectrode array production.

scholarly journals Assessing Surface Coverage of Aminophenyl Bonding Sites on Diazotised Glassy Carbon Electrodes for Optimised Electrochemical Biosensor Performance

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 416
Author(s):  
Zari Tehrani ◽  
Hina Yaqub Abbasi ◽  
Anitha Devadoss ◽  
Jonathan Edward Evans ◽  
Owen James Guy
Keyword(s):  
Carboxylic Acid ◽  
Surface Coverage ◽  
Electrochemical Biosensor ◽  
Electrochemical Techniques ◽  
Differential Pulse ◽  
Second Step ◽  
Glassy Carbon Electrodes ◽  
Potential Marker ◽  
Pulse Voltammetry ◽  
Amine Coupling

Electrochemical biosensors using carbon-based electrodes are being widely developed for the detection of a range of different diseases. Since their sensitivity depends on the surface coverage of bioreceptor moieties, it necessarily depends on the surface coverage of amine precursors. Electrochemical techniques, using ferrocene carboxylic acid as a rapid and cheap assay, were used to assess the surface coverage of amino-phenyl groups attached to the carbon electrode. While the number of electrons transferred in the first step of diazotisation indicated a surface coverage of 8.02 ± 0.2 × l0−10 (mol/cm2), and those transferred in the second step, a reduction of nitrophenyl to amino-phenyl, indicated an amine surface coverage of 4–5 × l0−10 (mol/cm2), the number of electrons transferred during attachment of the amine coupling assay compound, ferrocene carboxylic acid, indicated a much lower available amine coverage of only 2.2 × l0−11 (mol/cm2). Furthermore, the available amine coverage was critically dependent upon the number of cyclic voltammetry cycles used in the reduction, and thus the procedures used in this step influenced the sensitivity of any subsequent sensor. Amine coupling of a carboxyl terminated anti-beta amyloid antibody specific to Aβ(1-42) peptide, a potential marker for Alzheimer’s disease, followed the same pattern of coverage as that observed with ferrocene carboxylic acid, and at optimum amine coverage, the sensitivity of the differential pulse voltammetry sensor was in the range 0–200 ng/mL with the slope of 5.07 µA/ng·mL−1 and R2 = 0.98.

Ultrasensitive Electrochemical Determination of Phosphate in water by Hydrophilic TiO2 modified Glassy Carbon Electrodes

2021 ◽  
Author(s):  
Yan Jin ◽  
Tong QI ◽  
Yuqing Ge ◽  
Jin Chen ◽  
Li juan Liang ◽  
...  
Keyword(s):  
Differential Pulse Voltammetry ◽  
Glassy Carbon ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Carbon Electrodes ◽  
Glassy Carbon Electrodes ◽  
Time Differential ◽  
Pulse Voltammetry ◽  
First Time

In this paper, ultrasensitive electrochemical determination of phosphate in water is achieved by hydrophilic TiO2 modified glassy carbon electrodes for the first time. Differential pulse voltammetry (DPV) method is proposed...

scholarly journals INITIAL SURGICAL EXPERIENCE WITH A DENSE CORTICAL MICROARRAY IN EPILEPTIC PATIENTS UNDERGOING CRANIOTOMY FOR SUBDURAL ELECTRODE IMPLANTATION

Neurosurgery ◽  
2009 ◽  
Vol 64 (3) ◽  
pp. 540-545 ◽  
Author(s):  
Allen Waziri ◽  
Catherine A. Schevon ◽  
Joshua Cappell ◽  
Ronald G. Emerson ◽  
Guy M. McKhann ◽  
...  
Keyword(s):  
Local Field ◽  
Single Unit ◽  
Microelectrode Array ◽  
Tissue Injury ◽  
Local Field Potentials ◽  
Microelectrode Arrays ◽  
Field Potentials ◽  
Surgical Experience ◽  
Electrode Implantation ◽  
Subdural Electrode

Abstract OBJECTIVE Detailed investigations of cortical physiology require the ability to record brain electrical activity at a submillimeter scale. Standard intracranial electrodes result in significant averaging of potentials generated by large numbers of neurons. In contrast, microelectrode arrays allow for recording of local field potentials and single-unit activity. We describe our initial surgical experience with the NeuroPort microelectrode array (Cyberkinetics Neurotechnology Systems, Inc., Salt Lake City, UT) in a series of patients undergoing subdural electrode implantation for epilepsy monitoring. METHODS Seven patients were implanted with and underwent semichronic recording from the NeuroPort array during standard subdural electrode monitoring for epilepsy. The electrode was placed according to company specifications in putative noneloquent epileptogenic cortex. After the monitoring period, microelectrode arrays were removed during explantation of subdural electrodes and resection of epileptogenic tissue. RESULTS Successful implantation of the microelectrode array was achieved in all patients, with minor operative difficulties. Robust and durable local field potentials and single-unit recordings were obtained from all implanted individuals. Implantation times ranged from 3 to 28 days; histological analysis of implanted tissue demonstrated no significant tissue injury or inflammatory response. There were no neurological complications or infections associated with electrode implantation or prolonged monitoring. Two patients developed postresection issues with wound healing at the site of scalp egress, with 1 requiring operative wound revision. CONCLUSION Our experience demonstrates that semichronic microelectroencephalographic recording can be safely and effectively achieved using the NeuroPort microarray. Although significant tissue injury, infection, or cerebrospinal fluid leak was not encountered, the large profile of the connection pedestal resulted in suboptimal wound closure and healing in several patients. We predict that this problem will be easily addressed in second-generation devices.

scholarly journals Bare carbon electrodes as simple and efficient sensors for the quantification of caffeine in commercial beverages

2018 ◽  
Vol 5 (5) ◽  
pp. 172146 ◽  
Author(s):  
Luca Redivo ◽  
Miroslav Stredanský ◽  
Elisabetta De Angelis ◽  
Luciano Navarini ◽  
Marina Resmini ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
High Performance ◽  
Cost Effective ◽  
Differential Pulse ◽  
Routine Analysis ◽  
Carbon Electrodes ◽  
Current Response ◽  
Chromatography Method ◽  
Glassy Carbon Electrodes ◽  
Relative Standard

Food quality control is a mandatory task in the food industry and relies on the availability of simple, cost-effective and stable sensing platforms. In the present work, the applicability of bare glassy carbon electrodes for routine analysis of food samples was evaluated as a valid alternative to chromatographic techniques, using caffeine as test analyte. A number of experimental parameters were optimized and a differential pulse voltammetry was applied for quantification experiments. The detection limit was found to be 2 × 10 −5  M (3σ criterion) and repeatability was evaluated by the relative standard deviation of 4.5%. The influence of sugars, and compounds structurally related to caffeine on the current response of caffeine was evaluated and found to have no significant influence on the electrode performance. The suitability of bare carbon electrodes for routine analysis was successfully demonstrated by quantifying caffeine content in seven commercially available drinks and the results were validated using a standard ultra-high performance liquid chromatography method. This work demonstrates that bare glassy carbon electrodes are a simple, reliable and cost-effective platform for rapid analysis of targets such as caffeine in commercial products and they represent therefore a competitive alternative to the existing analytical methodologies for routine food analysis.

scholarly journals Bacterial handling under the influence of non-uniform electric fields: dielectrophoretic and electrohydrodynamic effects

2008 ◽  
Vol 80 (4) ◽  
pp. 627-638 ◽  
Author(s):  
Flavio H. Fernádez-Morales ◽  
Julio E. Duarte ◽  
Josep Samitier-Martí
Keyword(s):  
Electric Fields ◽  
Microelectrode Array ◽  
Viscous Drag ◽  
Liquid Motion ◽  
Dielectrophoretic Force ◽  
Electrode Surfaces ◽  
Biological Objects ◽  
Viscous Drag Force ◽  
Lift Off ◽  
Positive Dielectrophoresis

This paper describes the modeling and experimental verification of a castellated microelectrode array intended tohandle biocells, based on common dielectrophoresis. The proposed microsystem was developed employing platinumelectrodes deposited by lift-off, silicon micromachining, and photoresin patterning techniques. Having fabricated the microdevice it was tested employing Escherichia coli as bioparticle model. Positive dielectrophoresis could be verified with the selected cells for frequencies above 100 kHz, and electrohydrodynamic effects were observed as the dominant phenomena when working at lower frequencies. As a result, negative dielectrophoresis could not be observed because its occurrence overlaps with electrohydrodynamic effects; i.e. the viscous drag force acting on the particles is greater than the dielectrophoretic force at frequencies where negative dielectrophoresis should occur. The experiments illustrate the convenience of this kind of microdevices to micro handling biological objects, opening the possibility for using these microarrays with other bioparticles. Additionally, liquid motion as a result of electrohydrodynamic effects must be taken into account when designing bioparticle micromanipulators, and could be used as mechanism to clean the electrode surfaces, that is one of the most important problems related to this kind of devices.

Sign in / Sign up

Export Citation Format

Share Document