Poisoning of Highly Porous Platinum Electrodes by Amino Acids and Tissue Fluid Constituents

2015 ◽  
Vol 2 (11) ◽  
pp. 1785-1793 ◽  
Author(s):  
Christian Köhler ◽  
Lena Bleck ◽  
Maxi Frei ◽  
Roland Zengerle ◽  
Sven Kerzenmacher
Keyword(s):  
Amino Acids ◽  
Tissue Fluid ◽  
Platinum Electrodes ◽  
Highly Porous

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

scholarly journals Highly Porous Platinum Electrodes for Dry Ear-EEG Measurements

2020 ◽  
Author(s):  
Max Eickenscheidt ◽  
Patrick Schäfer ◽  
Yara Baslan ◽  
Claudia Schwarz ◽  
Thomas Stieglitz
Keyword(s):  
Growth Form ◽  
Silver Chloride ◽  
Auditory Attention ◽  
Platinum Electrodes ◽  
Effective Surface Area ◽  
Effective Surface ◽  
Transmission Properties ◽  
Silver Silver ◽  
Silver Silver Chloride ◽  
Highly Porous

The interest in dry EEG electrodes has increased in recent years and especially as everyday suitability earplugs for measuring drowsiness or focus of auditory attention. However, the challenge is still the need for a good electrode material, which is reliable and can be easily processed for highly personalized applications. Laser processing as used here is a fast and very precise method to produce personalized electrode configurations that meet the high requirements of in-ear EEG electrodes, for example. The arrangement of the electrodes on the very flexible and compressible mats allows an exact alignment of the electrodes to the ear mold and contributes to a high wearing comfort, as no edges or metal protrusions are present. For better transmission properties, an adapted coating process for surface enlargement of platinum electrodes is used, which allows easy control of the thickness and growth form of the porous layer. The porous platinum-copper alloy is chemically very stable, shows no exposed copper residues and enlarges the effective surface area by 40. In a proof-of-principle experiment, these porous platinum electrodes could be used to measure the Berger effect in a dry state using just one ear of a test person. Their signal-to-noise ration and frequency transfer function is comparable to gel-based silver/silver chloride electrodes.

scholarly journals Highly Porous Platinum Electrodes for Dry Ear-EEG Measurements

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3176 ◽  
Author(s):  
Max Eickenscheidt ◽  
Patrick Schäfer ◽  
Yara Baslan ◽  
Claudia Schwarz ◽  
Thomas Stieglitz
Keyword(s):  
Silver Chloride ◽  
Signal To Noise Ratio ◽  
Auditory Attention ◽  
Platinum Electrodes ◽  
Effective Surface Area ◽  
Effective Surface ◽  
Transmission Properties ◽  
Silver Silver ◽  
Silver Silver Chloride ◽  
Highly Porous

The interest in dry electroencephalography (EEG) electrodes has increased in recent years, especially as everyday suitability earplugs for measuring drowsiness or focus of auditory attention. However, the challenge is still the need for a good electrode material, which is reliable and can be easily processed for highly personalized applications. Laser processing, as used here, is a fast and very precise method to produce personalized electrode configurations that meet the high requirements of in-ear EEG electrodes. The arrangement of the electrodes on the flexible and compressible mats allows an exact alignment to the ear mold and contributes to high wearing comfort, as no edges or metal protrusions are present. For better transmission properties, an adapted coating process for surface enlargement of platinum electrodes is used, which can be controlled precisely. The resulting porous platinum-copper alloy is chemically very stable, shows no exposed copper residues, and enlarges the effective surface area by 40. In a proof-of-principle experiment, these porous platinum electrodes could be used to measure the Berger effect in a dry state using just one ear of a test person. Their signal-to-noise ratio and the frequency transfer function is comparable to gel-based silver/silver chloride electrodes.

scholarly journals Cyclic Electrodeposition of PtCu Alloy: Facile Fabrication of Highly Porous Platinum Electrodes

2012 ◽  
Vol 24 (21) ◽  
pp. 2916-2921 ◽  
Author(s):  
Arne Kloke ◽  
Christian Köhler ◽  
Ramona Gerwig ◽  
Roland Zengerle ◽  
Sven Kerzenmacher
Keyword(s):  
Platinum Electrodes ◽  
Facile Fabrication ◽  
Ptcu Alloy ◽  
Highly Porous

Fabrication of highly porous platinum electrodes for micro-scale applications by pulsed electrodeposition and dealloying

2013 ◽  
Vol 242 ◽  
pp. 255-263 ◽  
Author(s):  
Christian Köhler ◽  
Arne Kloke ◽  
Anna Drzyzga ◽  
Roland Zengerle ◽  
Sven Kerzenmacher
Keyword(s):  
Platinum Electrodes ◽  
Micro Scale ◽  
Pulsed Electrodeposition ◽  
Highly Porous

scholarly journals Amino Acids Aided Sintering for the Formation of Highly Porous FeAl Intermetallic Alloys

Materials ◽  
2017 ◽  
Vol 10 (7) ◽  
pp. 746 ◽  
Author(s):  
Krzysztof Karczewski ◽  
Wojciech Stepniowski ◽  
Marco Salerno
Keyword(s):  
Amino Acids ◽  
Intermetallic Alloys ◽  
Highly Porous

Model to assess muscle protein turnover: domain of validity using amino acyl-tRNA vs. surrogate measures of precursor pool

2003 ◽  
Vol 285 (5) ◽  
pp. E1142-E1149 ◽  
Author(s):  
Gianna Toffolo ◽  
Robert Albright ◽  
Michael Joyner ◽  
Niki Dietz ◽  
Claudio Cobelli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Compartment Model ◽  
Tissue Fluid ◽  
Protein Breakdown ◽  
Muscle Protein Turnover ◽  
Three Compartment Model ◽  
Surrogate Measures ◽  
Domain Of Validity

Current models to measure protein turnover across muscle bed are based on many surrogate measures of amino acyl-tRNA. We measured muscle protein turnover based on tracer-to-tracee ratios of the stable isotopes of leucine, phenylalanine, and ketoisocaproate (KIC) in artery and vein and muscle amino acyl-tRNA and muscle tissue fluid (TF) in 26 healthy subjects. A three-compartment model calculation based on arteriovenous and tRNA measurements was first performed and its domain of validity assessed. The results were then compared with those using simpler approaches based on surrogate measures of tRNA such as those of TF and KIC and a one-compartment model based on arteriovenous amino acids. In 96% of cases, the model using tRNA was applicable, but only in a lower percentage of cases were the results using surrogate measures applicable. Protein breakdown, protein synthesis, and shunting of amino acids from artery to vein were consistently underestimated, and fluxes of amino acid from artery to intracellular compartment and from intracellular compartment to vein were overestimated, when surrogate measures were used. The one-compartment model also underestimated protein breakdown and synthesis. Measurements using tissue fluid gave results closer to those based on tRNA. In conclusion, a three-compartment model using arteriovenous samples and amino acyl-tRNA provides measurements of muscle protein turnover of acceptable precision in 96% of cases. The precision was unacceptable in a substantial percentage of cases, and the accuracy of the estimation of protein fluxes was significantly affected when surrogate measures were used.

Aminoacyl-tRNA enrichment after a flood of labeled phenylalanine: insulin effect on muscle protein synthesis

2002 ◽  
Vol 282 (5) ◽  
pp. E1029-E1038 ◽  
Author(s):  
Giuseppe Caso ◽  
G. Charles Ford ◽  
K. Sreekumaran Nair ◽  
Peter J. Garlick ◽  
Margaret A. McNurlan
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Time Course ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Early Time ◽  
Tissue Fluid ◽  
Insulin Effect ◽  
Precursor Pool ◽  
Plasma Phenylalanine

Muscle protein synthesis in dogs measured by flooding withl-[2H5]phenylalanine (70 mg/kg) was significantly stimulated by infusion of insulin with amino acids. The stimulation of muscle protein synthesis was similar when calculated from the enrichment of phenylalanyl-tRNA (61 ± 10%, P< 0.001), plasma phenylalanine (61 ± 10%, P < 0.001), or tissue fluid phenylalanine (54 ± 10%, P < 0.001). The time course for changes in enrichment ofl-[2H5]phenylalanine throughout the flooding period was determined for plasma, tissue fluid, and phenylalanyl-tRNA in the basal state and during the infusion of insulin with amino acids. Enrichments of plasma free phenylalanine and phenylalanyl-tRNA were equalized between 20 and 45 min, although the enrichment of phenylalanyl-tRNA was lower at early time points. Rates of muscle protein synthesis obtained with the flooding method and calculated from plasma phenylalanine enrichment were comparable to those calculated from phenylalanyl-tRNA and also to those obtained previously with a continuous infusion of phenylalanine with phenylalanyl-tRNA as precursor. This study confirms that, with a bolus injection of labeled phenylalanine, the enrichment of aminoacyl-tRNA, the true precursor pool for protein synthesis, can be assessed from more readily sampled plasma phenylalanine.

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